U.S. patent application number 10/100533 was filed with the patent office on 2002-11-07 for plasma device.
Invention is credited to Hirayama, Masaki, Kaiwara, Ryu, Nitta, Takahisa, Ohmi, Tadahiro, Takano, Haruyuki.
Application Number | 20020164883 10/100533 |
Document ID | / |
Family ID | 27281140 |
Filed Date | 2002-11-07 |
United States Patent
Application |
20020164883 |
Kind Code |
A1 |
Ohmi, Tadahiro ; et
al. |
November 7, 2002 |
Plasma device
Abstract
A plasma device which is provided with a container (100), a gas
supply system, and an exhaust system. The container (100) is
composed of a first dielectric plate (102) made of a material
capable of transmitting microwaves. An antenna (201) for radiating
microwaves is located on the outside of the container (100), and an
electrode (109) for holding an object (104) to be treated is
located inside the container (100). The microwave radiating surface
of the antenna (201) and the surface of the object (104) to be
treated with plasma are positioned in parallel and opposite to each
other. A wall section of the container (100) other than that
constituting the first dielectric plate (102) is composed of a
member of a material having electrical conductivity higher than
that of aluminium, or the internal surface of the wall section is
covered with the member. The thickness (d) of the member is larger
that 2/.mu..sub.0.sigma.).sup.1/2, where .sigma., .mu..sub.0 and
.omega. respectively represent the electrical conductivity of the
member, the permeability of vacuum and the angular frequency of the
microwaves radiated from the antenna.
Inventors: |
Ohmi, Tadahiro; (Miyagi-ken,
JP) ; Nitta, Takahisa; (Tokyo, JP) ; Hirayama,
Masaki; (Miyagi-ken, JP) ; Takano, Haruyuki;
(Miyagi-ken, JP) ; Kaiwara, Ryu; (Miyagi-ken,
JP) |
Correspondence
Address: |
RANDALL J. KNUTH P.C.
3510-A STELLHORN ROAD
FORT WAYNE
IN
46815-4631
US
|
Family ID: |
27281140 |
Appl. No.: |
10/100533 |
Filed: |
March 18, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10100533 |
Mar 18, 2002 |
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09355229 |
Oct 5, 1999 |
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6357385 |
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Current U.S.
Class: |
438/726 |
Current CPC
Class: |
H01L 21/0217 20130101;
H01L 21/31675 20130101; H01L 21/02252 20130101; H01L 21/31625
20130101; H01L 21/31691 20130101; H01L 21/02247 20130101; H01J
37/3244 20130101; H01L 21/02274 20130101; H01L 21/02129 20130101;
H01J 37/32238 20130101; H01L 21/02115 20130101; H01L 21/02238
20130101; H01L 21/02164 20130101; C23C 16/511 20130101; H01L
21/31612 20130101; H01L 21/0212 20130101; H01L 21/02197 20130101;
H01J 37/32192 20130101 |
Class at
Publication: |
438/726 |
International
Class: |
H01L 021/302 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 1997 |
JP |
9/15790 |
May 23, 1997 |
JP |
9/133422 |
Sep 25, 1997 |
JP |
9/278062 |
Claims
What is claimed is:
1) A plasma device comprising: a container, the inside of which can
be internally decompressed, and part of the inside being formed of
a first dielectric plate made of material capable of transmitting
microwaves with almost no loss, a gas supply system for supplying
essential source material gas so as to cause excitation of plasma
inside the container, an exhaust system for expelling source
material gas that has been supplied into the container and
decompressing the inside of the container, an antenna, located
facing an outer surface of the first dielectric plate and comprised
of a slot plate and a waveguide dielectric, for radiating
microwaves, and an electrode for holding a object to be treated
located inside the container, a surface of the object to be treated
to be subject to plasma processing and a microwave radiating
surface of the antenna being arranged in parallel substantially
opposite to each other, and the plasma device carrying out plasma
processing for the object to be treated, wherein, a wall section of
the container outside the first dielectric plate is of a material
comprising matter having a conductivity of
3.7.times.10.sup.7.OMEGA..sup.-1 or more, or the inside of the wall
section is covered with this material, and where thickness of the
material is d, the specific conductivity of the material is
.sigma., the magnetic permeability of vacuum is .mu..sub.0, and the
angular frequency of microwaves radiated from the antenna is
.omega., the thickness d is larger than
(2/.mu..sub.0.sigma..omega.).sup.1/2.
2) The plasma device as disclosed in claim 1, wherein: a first O
ring is located between an inner surface of the first dielectric
body and a wall section of the container; and a thin film formed of
a conductive material is provided on at least a surface of the
first dielectric plate coming into contact with the first O ring,
as means for preventing the first O ring from being directly
exposed to microwaves radiated from the antenna.
3) The plasma device as disclosed in claim 2, wherein said thin
film is formed from a material having a conductivity of at least
3.7.times.10.sup.7.OMEGA..sup.-1.multidot.m.sup.-1, and has a
thickness of at least 10 .mu.m.
4) The plasma device as disclosed in claim 1, wherein: a first O
ring having a vacuum sealing function is located between an inner
surface of the first dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
coated on the surface of the first O ring, for preventing the first
O ring from being directly exposed to microwaves radiated from the
antenna.
5) The plasma device as disclosed in claim 4, wherein said metallic
thin film is formed from a material having a conductivity of at
least 3.7.times.10.sup.7.OMEGA..sup.-1.multidot.m.sup.-1, and has a
thickness of at least 10 .mu.m.
6) The plasma device as disclosed in claim 1, wherein a second
dielectric plate having a gas inlet for substantially uniformly
supplying desired gas is provided between the first dielectric
plate and the electrode for holding the object to be processed.
7) The plasma device as disclosed in claim 6, wherein: a second O
ring having a vacuum sealing function is located between an inner
surface of the second dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
provided on at least a surface of the second dielectric plate
coming into contact with the second O ring, as means for preventing
the second O ring from being directly exposed to microwaves
radiated from the antenna.
8) The plasma device as disclosed in claim 6, wherein: a second O
ring having a vacuum sealing function is located between an inner
surface of the second dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
coated on the surface of the second O ring, as means for preventing
the second O ring from being directly exposed to microwaves
radiated from the antenna.
9) The plasma device as disclosed in claim 1, wherein the first
dielectric plate is formed of a material having a dielectric loss
angle tan .delta. of less than 10.sup.-3.
10) The plasma device as disclosed in claim 6, wherein the second
dielectric plate is formed of a material having a dielectric loss
angle tan .delta. of less than 10.sup.-3.
11) The plasma device as disclosed in claim 1, wherein a space is
formed between the antenna and the first dielectric plate.
12) The plasma device as disclosed in claim 11, wherein a line for
supplying heating medium communicates with the space formed between
the antenna and the first dielectric plate.
13) The plasma device as disclosed in claim 6, wherein the
frequency of microwaves fed to the antenna is at least 5.0 GHz, and
a width of a space 1 between the first dielectric plate and the
second dielectric plate is less than 0.7 mm.
14) The plasma device as disclosed in claim 6, provided with means
for generating a pressure difference so that a pressure 1 of the
space 1 between the first dielectric plate and the second
dielectric plate is higher than a pressure 2 of a space 2, in which
the electrode for holding the object to be treated is located, and
which is surrounded by the second dielectric plate and a wall
section of the container other than the second dielectric
plate.
15) The plasma device as disclosed in claim 6, wherein means for
introducing heating medium is connected into the space 2 surrounded
by the second dielectric plate and a wall section of the container
other than the second dielectric plate.
16) The plasma device of claim 14, the antenna being provided with
a slot plate functioning as a microwave radiating surface, and slot
sets comprising a holes penetrating the slot plate at a plurality
of fixed location wherein, at portions where the density of plasma
generated in the space 2 is locally higher than other portions, the
slots either have a smaller diameter than at other portions, are
screened by a screen plate, or are not provided at all.
17) The plasma device as disclosed in claim 1, provided with means
6 for cooling the antenna.
18) The plasma device as disclosed in claim 17, wherein a
passageway is formed in the antenna guide, and a line for supplying
heating medium communicates with the passageway.
19) The plasma device as disclosed in claim 1, provided with means
7 for cooling the first dielectric plate.
20) The plasma device as disclosed in claim 1, provided with means
8 preventing warping of the slot plate.
21) The plasma device as disclosed in claim 20, wherein a space is
provided between the antenna and the first dielectric plate, and a
plate composed of a flexible member is interposed in the space as
means for preventing warping of the slot plate.
22) The plasma device as disclosed in claim 1, provided with means
9 for detecting the presence or absence of plasma generated in the
space 2.
23) The plasma device as disclosed in claim 1, provided with a
mechanism for causing the temperature of a wall section inside the
container and sections inside the container other than the object
to be treated, to respectively rise to 150.degree. C.
24) The plasma device as disclosed in claim 1, wherein the exhaust
system is provided with a mechanism for causing the temperature
inside all units comprising the exhaust system, to respectively to
rise to 150.degree. C.
25) The plasma device as disclosed in claim 1, wherein the
electrode having the function of holding the object to be treated
has a mechanism for heating the object to be treated.
26) The plasma device as disclosed in claim 25, wherein a xenon
lamp is used as the mechanism for heating the object to be
treated.
27) The plasma device as disclosed in claim 1, wherein a mechanism
for collecting and recycling fluorocarbon type gas is provided
downstream of the exhaust system.
28) The plasma device as disclosed in any one of claims 1 to 20,
wherein a film comprising AlF.sub.3 and MgF.sub.2 is formed on an
inner wall surface of the container.
29) The plasma device as disclosed in claim 1, wherein the
electrode having the function of holding the object to be treated
is provided with a dc bias and/or an ac bias applying means.
30) The plasma device as disclosed in claim 1, wherein said plasma
device is a device for carrying out etching of a surface the object
to be treated.
31) The plasma device as disclosed in claim 1, wherein said plasma
device is a device for causing direct oxidation of a surface of the
object to be treated.
32) The plasma device as disclosed in claim 1, wherein said plasma
device is a device for causing direct nitridation of a surface of
the object to be treated.
33) The plasma device as disclosed in claim 1, wherein said plasma
device is a device for causing a thin film to be deposited on the
object to be treated.
34) A plasma processing method using a plasma device comprising a
container, the inside of which can be internally decompressed, and
part of the inside being formed of a first dielectric plate made of
material capable of passing microwaves with almost no loss, a gas
supply system for supplying essential source material gas so as to
cause excitation of plasma inside the container, an exhaust system
for expelling source material gas that has been supplied inside the
container and decompressing the inside of the container, an
antenna, located facing an outer surface of the first dielectric
plate and comprised of a slot plate and a waveguide dielectric, for
radiating microwaves, and an electrode for holding an object to be
treated located inside the container, a surface of the object to be
treated that is to be subject to plasma processing and a microwave
radiating surface of the antenna being arranged in parallel
substantially opposite to each other, and the plasma device
carrying out plasma processing for the object to be treated, the
power density of microwaves to be input being 1.2 W/cm.sup.2 or
more.
35) The plasma processing method as disclosed in claim 34, wherein
a pressure 1 of the space 1 between the first dielectric plate and
the second dielectric plate is made higher than a pressure 2 of a
space 2, in which the electrode for holding the object to be
treated is located, and which is surrounded by the second
dielectric plate and a wall section of the container other than the
second dielectric plate.
36) A plasma device comprising: an electrode I inside a vacuum
container, with a substrate to be subjected to processing using
plasma being mounted so as to be connected to this electrodes, and
magnetic field applying means I and II provided outside the vacuum
container, for applying a magnetic field to the inside of the
plasma, wherein at least some of a gas that has been introduced
into the vacuum container is expelled through a space between the
magnetic field applying-means I and II.
37) The plasma device as disclosed in claim 36, wherein the
magnetic field applying means I and II are annular magnets
comprising a plurality of permanent magnets.
38) The plasma device as disclosed in claim 36 or claim 37, wherein
the magnetic field is substantially horizontal with respect to a
surface of the substrate that is to be subject to plasma
processing, and is substantially unidirectional.
39) A plasma device, provided with two parallel plate type
electrodes I and II inside a vacuum container, and a substrate to
be subjected to processing using plasma being mounted so as to be
connected to either the electrode I or the electrode II, and means
for applying a magnetic field to the inside of the plasma, the
electrode II comprising a central section, and an outer section
connected to a high frequency power source that can be controlled
independently of a high frequency power source connected to the
electrode I.
40) The plasma device as disclosed in claim 39, wherein a central
portion of the electrode II is electrically grounded.
41) The plasma device as disclosed in claim 39 or claim 40, wherein
the magnetic field is substantially horizontal with respect to a
surface of the substrate that is to be subject to plasma
processing, and is substantially unidirectional.
42) The plasma device as disclosed in claim 39 or claim 40, wherein
the magnetic field is applied using an annular magnet comprising a
plurality of permanent magnets provided outside the vacuum
container.
43) The plasma device as disclosed in claim 39, claim 40 or claim
41, wherein the magnetic field is applied using annular magnets I
and II comprising a plurality of permanent magnets provided outside
the vacuum container, and at least some of the gas that has been
introduced into the vacuum container is expelled by passing between
the magnets I and II.
44) The plasma device as disclosed in any one of claims 36-43,
wherein at least some of the gas that has been introduced into the
vacuum container is expelled from three or more exhaust outlets
having substantially the same cross sectional area and located at
the edge of the substrate at substantially axially symmetrical
positions with respect to an axis vertical to the substrate surface
and passing through the center of the substrate.
45) A plasma device having an electrode provided in a vacuum
container, and a substrate to be subjected to plasma processing is
mounted so as to come into contact with the electrode, wherein at
least some of a gas that has been introduced into the vacuum
container is expelled from three or more exhaust outlets having
substantially the same cross sectional area and located at the edge
of the substrate at substantially axially symmetrical positions
with respect to an axis vertical to the substrate surface and
passing through the center of the substrate.
46) The plasma device as disclosed in claim 44 or claim 45, wherein
a vacuum pump is connected to each exhaust outlet.
47) A plasma device with an exhaust space formed in direct contact
with an intake port of a vacuum port provided beside of a film
formation space above a substrate.
48) The plasma device as disclosed in claim 47, wherein the width
of the exhaust space is at least double the height of the film
formation space.
49) The plasma device as disclosed in claim 47, wherein two or more
vacuum pumps having substantially the same intake port area are
arranged at symmetrical positions with respect to a substantially
central point of the substrate.
50) The plasma device as disclosed in claim 47, wherein the film
formation space is located in an upper, lower or side part of the
intake port of the vacuum pump.
51) A plasma device comprising: a container, the inside of which
can be internally decompressed, and part of the inside being formed
of a first dielectric plate made of material capable of passing
microwaves with almost no loss, a gas supply system for supplying
essential source material gas so as to cause excitation of plasma
inside the container, an exhaust system for expelling source
material gas that has been supplied inside the container and
decompressing the inside of the container, an antenna, located
facing an outer surface of the first dielectric plate and comprised
of a slot plate and a waveguide dielectric, for radiating
microwaves, and an electrode for holding an object to be treated
located inside the container, a surface of the object to be treated
that is to be subject to plasma processing and a microwave
radiating surface of the antenna being arranged in parallel
substantially opposite to each other, and the plasma device
carrying out plasma processing for the object to be treated,
wherein, an exhaust space formed directly communicating with an
inlet of a vacuum pump is provided to the side of a film forming
space above the substrate.
52) The plasma device as disclosed in claim 51, wherein the width
of the exhaust space is at least double the height of the film
formation space.
53) The plasma device as disclosed in claim 51, wherein: a wall
section of the container outside the first dielectric plate is of a
material comprising material having a conductivity of
3.7.times.10.sup.7.OMEGA..su- p.-1/m.sup.-1 or more, or the inside
of the wall section is covered with this material, and where when
thickness of the material is d, the specific conductivity of the
material is .sigma., the magnetic permeability of vacuum is
.mu..sub.0, and the angular frequency of microwaves radiated from
the antenna is .omega., the thickness d is larger than
(2/.mu..sub.0.sigma..omega.).sup.1/2.
54) The plasma device as disclosed in claim 51, wherein: a first O
ring is located between an inner surface of the first dielectric
body and a wall section of the container; and a thin film formed of
a conductive material is provided on at least a surface of the
first dielectric plate coming into contact with the first O ring,
as means for preventing the first O ring from being directly
exposed to microwaves radiated from the antenna.
55) The plasma device as disclosed in claim 54, wherein the thin
film is formed of a material having a conductivity of
3.7.times.10.sup.7.OMEGA..s- up.-1/m.sup.-1 or more, and has a
thickness of at least 10 .mu.m.
56) The plasma device as disclosed in claim 55, wherein: a first O
ring having a vacuum sealing function is located between an inner
surface of the first dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
coated on the surface of the first O ring, as means for preventing
the first O ring from being directly exposed to microwaves radiated
from the antenna.
57) The plasma device as disclosed in claim 56, wherein said
metallic thin film is formed from a material having a conductivity
of at least 3.7.times.10.sup.7.OMEGA..sup.-1.multidot.m.sup.-1, and
has a thickness of at least 10 .mu.m.
58) The plasma device as disclosed in claim 51, wherein a second
dielectric plate having a gas inlet for substantially uniformly
supplying desired gas is provided between the first dielectric
plate and the electrode for holding the object to be processed.
59) The plasma device as disclosed in claim 58, wherein: a second O
ring having a vacuum sealing function is located between an inner
surface of the second dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
provided on at least a surface of the second dielectric plate
coming into contact with the second O ring, as means for preventing
the second O ring from being directly exposed to microwaves
radiated from the antenna.
60) The plasma device as disclosed in claim 58, wherein: a second O
ring having a vacuum sealing function is located between an inner
surface of the second dielectric body and a wall section of the
container; and a thin film formed of a conductive material is
coated on the surface of the second O ring, as means for preventing
the second O ring from being directly exposed to microwaves
radiated from the antenna.
61) The plasma device as disclosed in claim 51, wherein the first
dielectric plate is formed of a material having a dielectric loss
angle tan .delta. of less than 10.sup.-3.
62) The plasma device as disclosed in claim 58, wherein the second
dielectric plate is formed of a material having a dielectric loss
angle tan .delta. of less than 10.sup.-3.
63) The plasma device as disclosed in claim 51, wherein a space is
formed between the antenna and the first dielectric plate.
64) The plasma device as disclosed in claim 63, wherein a line for
supplying heating medium communicates with the space formed between
the antenna and the first dielectric plate.
65) The plasma device as disclosed in claim 58, wherein the
frequency of microwaves fed to the antenna is at least 5.0 GHz, and
a width of a space 1 between the first dielectric plate and the
second dielectric plate is less than 0.7 mm.
66) The plasma device as disclosed in claim 58, provided with means
for generating a difference pressure so that a pressure 1 of the
space 1 between the first dielectric plate and the second
dielectric plate is higher than a pressure 2 of space 2, in which
the electrode for holding the object to be treated is located, and
which is surrounded by the second dielectric plate and a wall
section of the container other than the second dielectric
plate.
67) The plasma device as disclosed in claim 58, wherein means for
introducing heating medium is connected into the space 2 surrounded
by the second dielectric plate and a wall section of the container
other than the second dielectric plate.
68) The plasma device of claim 51, the antenna being provided with
a slot plate functioning as a microwave radiating surface, and slot
sets comprising hole sections (hereinafter called slots)
penetrating the slot plate at a plurality of fixed locations,
wherein, at portions where the density of plasma generated in the
space 2 is locally higher than other portions, the hole slots
either have a smaller diameter than at other portions, are screened
by a screen plate, or are not provided at all.
69) The plasma device as disclosed in claim 51, provided with means
for cooling the antenna.
70) The plasma device as disclosed in claim 69, wherein a
passageway is formed in the antenna guide, and a line for supplying
heating medium is connected to the passageway.
71) The plasma device as disclosed in claim 51, provided with means
7 for cooling the first dielectric plate.
72) The plasma device as disclosed in claim 51, provided with means
8 for preventing bending of the slot plate.
73) The plasma device as disclosed in claim 72 wherein a space is
provided between the antenna and the first dielectric plate, and a
plate composed of a flexible member is interposed in the space as
means for preventing bending of the slot plate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plasma device.
BACKGROUND OF THE INVENTION
[0002] Recently, accompanying the increase in chip size of ULSI
(ultra large scale integrated circuits), there has also been a
tendency to increase the diameter of a silicon substrate used as a
substrate for the ULSI. Since sheet leaf processing for handling
substrates one at a time has become mainstream, if the substrate is
increased in diameter there is a need for high speed processing of
at least 1 mm per minute in order to maintain high productivity if
etching and film forming are carried out. In a plasma device for
handling an increased diameter substrate enabling high speed
processing, it is essential to be able to generate high density
plasma having an electron density in excess of 10.sup.11 cm.sup.-3
and to obtain the flow of a large quantity of gas in order to
efficiently remove a large amount of reaction products discharged
from the substrate surface as a result of the high speed
processing. In order to enable the generation of high density
plasma, a parallel plate type plasma device introducing a magnetic
field has been developed. As a conventional plasma device of this
type, a magnetron plasma etching device using a dipole ring magnet
is disclosed in, for example, Japanese Patent Laid Open No. Hei.
6-37054.
[0003] FIG. 43 is a schematic diagram of the conventional magnetron
plasma etching device using a dipole ring magnet. FIG. 43(a)
shows-the state at the time of etching, and FIG. 43(b) shows the
state at the time of conveying the substrate. In the drawings,
reference numeral 4301 is a vacuum vessel, reference numeral 4302
is an electrode I, reference numeral 4303 is a substrate, reference
numeral 4304 is a gas introduction opening, reference numeral 4305
is a shower plate, reference numeral 4306 is a dipole ring magnet,
reference numeral 4307 is a bellows, reference numeral 4308 is a
porous plate, reference numeral 4309 is a gate valve, reference
numeral 4310 is a substrate conveying port, reference numeral 4311
is a gas outlet, reference numeral 4312 is a vacuum pump, reference
numeral 4313 is a matching circuit and reference numeral 4314 is a
high frequency power source.
[0004] At the time of etching, source material gas that has been
introduced from the gas introduction opening 4304 is discharged
from a plurality of small holes in the shower plate 4305. This
source material gas and reaction product gas discharged from the
substrate surface as a result of the etching reaction are
discharged to the outside, through a side section of the electrode
I 4302, the porous plate 4308 and the gas outlet 4311, by the expel
pump 4312. The porous plate 4308 causes a lowering of the gas
conductance between a space above the substrate 4303 and the gas
outlet 4311, and is provided so as to make the gas flow
substantially uniformly in a direction of rotation of the space
above the substrate 4303. Since the gas is made to flow uniformly
in a direction of rotation of the space above the substrate 4303,
the gas conductance between the space above the substrate 4303 and
the gas outlet 4311 is inevitably restricted and there is a problem
that a large amount of gas can not flow. As a result, in high speed
etching on large diameter substrates the etching rate is lowered,
and a problem arises that the etching shape degenerates.
[0005] At the time of conveying the substrate, the position of the
electrode I 4302 is lowered, as in FIG. 43(b), and the substrate is
conveyed through the gate valve 4309 and the substrate conveying
port 4310 using an external substrate conveyance machine. The
bellows 4307 are required in order to cause the electrode I 4302 to
move. At the time of plasma generation, power loss occurs due to
high frequency current flowing in the bellows 4307, and there is a
problem that the high frequency output power of the high frequency
power source 4314 can not be efficiently supplied to the plasma.
There is also a problem that a complex structure is required
because the electrode I 4302 is made to move.
[0006] A device using electron cyclotron resonance (ECR) is also
known as a plasma device using microwaves. This device enables
excitation of high density uniform plasma on a substrate, but since
the method involves high density plasma being excited locally,
caused to widely diffuse within the container and uniformly
supplied onto a object to be treated, installation of a shower
plate is difficult, and it is difficult to promptly remove gases
that are reaction by-products.
[0007] As a high density plasma device using microwaves, a device
using a radial line slot antenna is also known (Japanese patent
laid-open No. Hei.8-111297). However, if this device is put to
practical use, it is not always possible to cause high density
plasma to be generated stably over a long period of time. Also, the
conditions for causing the generation of plasma are not
definite.
[0008] The object of the present invention is to provide a plasma
processing device, within a narrow space inside a container that
enables uniform formation of a high quality thin film on a large
substrate at a low temperature and at high speed, by causing
excitation of uniform high density plasma having a low plasma
potential over a large surface area, making supply of source
material gas uniform, and swiftly removing reaction by-product
gases by adopting a structure equivalent to a shower plate. The
invention is applicable to plasma processing other than an etching
plasma process.
DISCLOSURE OF THE INVENTION
[0009] A plasma device of the present invention comprises
[0010] a container, the inside of which can be internally
decompressed, and part of the inside being formed of a first
dielectric plate made of material capable of passing microwaves
with almost no loss,
[0011] a gas supply system for supplying essential source material
gas so as to cause excitation of plasma inside the container,
[0012] an exhaust system for expelling source material gas supplied
into the container and decompressing the inside of the
container,
[0013] an antenna, located facing an outer surface of the first
dielectric plate and comprised of a slot plate and a waveguide
dielectric, for radiating microwaves, and
[0014] an electrode for holding a object to be treated located
inside the container, a surface of the object to be treated that is
to be plasma processed and a microwave radiating surface of the
antenna being arranged in parallel substantially opposite to each
other, and the plasma device carrying out plasma processing for the
object to be treated, wherein,
[0015] a wall section of the container outside the first dielectric
plate is of a material comprising matter having a specific
conductivity of 3.7.times.10.sup.7 .OMEGA..sup.-1/m.sup.-1 or more,
or the inside of the wall section is covered with this material,
and
[0016] when thickness of the material is d, the specific
conductivity of the material is .sigma., the magnetic permeability
of the vacuum is .mu..sub.0, and the angular frequency of
microwaves radiated from the antenna is .omega., the thickness d is
larger than (2/.mu..sub.0.sigma..omega.).sup.1/2.
[0017] A plasma processing method of the present invention is a
method using a plasma device comprising a container, the inside of
which can be internally decompressed, and part of the inside being
formed of a first dielectric plate made of material capable of
passing microwaves with almost no loss, a gas supply system for
supplying essential source material gas so as to cause excitation
of plasma inside the container, an exhaust system for expelling
source material gas that has been supplied inside the container and
decompressing the inside of the container, an antenna, located
facing an outer surface of the first dielectric plate and comprised
of a slot plate and a waveguide dielectric, for radiating
microwaves, and an electrode for holding an object to be treated
located inside the container, a surface of the object to be treated
that is to be subject to plasma processing and a microwave
radiating surface of the antenna being arranged in parallel
substantially opposite to each other, and the plasma device
carrying out plasma processing for the object to be treated, the
power density of microwaves to be input being 1.2 W/cm.sup.2 or
more. This method assures stable generation of plasma.
[0018] A plasma device of the present invention is provided with an
electrode I inside a vacuum container, and a substrate to be
subjected to processing using plasma is mounted so as to be
connected to this electrode I. Magnetic field applying means I and
II are provided outside the vacuum container, for the purpose of
applying a magnetic field to the inside of the plasma, and at least
some of a gas that has been introduced into the vacuum container is
expelled through a space between the magnetic field applying means
I and II.
[0019] A plasma device of the present invention is provided with
two parallel plate type electrodes I and II inside a vacuum
container, and a substrate to be subjected to processing using
plasma is mounted so as to be connected to either the electrode I
or the electrode II. Means for applying a magnetic field to the
inside of the plasma are provided, and the electrode II comprises a
central section, and an outer section connected to a high frequency
power source that can be controlled independently of a high
frequency power source connected to the electrode I.
[0020] A plasma device of the present invention is provided with an
exhaust space formed directly communicating with an inlet of a
vacuum pump, to the side of a film forming space above the
substrate.
[0021] A plasma device of the present invention comprises
[0022] a container, the inside of which can be internally
decompressed, and part of the inside being formed of a first
dielectric plate made of material capable of passing microwaves
with almost no loss,
[0023] a gas supply system for supplying essential source material
gas so as to cause excitation of plasma inside the container,
[0024] an exhaust system for expelling source material gas that has
been supplied inside the container and decompressing the inside of
the container,
[0025] an antenna, located facing an outer surface of the first
dielectric plate and comprised of a slot plate and a waveguide
dielectric, for radiating microwaves, and
[0026] an electrode for holding a object to be treated located
inside the container, a surface of the object to be treated that is
to be subject to plasma processing and a microwave radiating
surface of the antenna being arranged in parallel substantially
opposite to each other, and the plasma device carrying out plasma
processing for the object to be treated, wherein,
[0027] an exhaust space formed directly communicating with an inlet
of a vacuum pump is provided to the side of a film forming space
above the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a cross section of a device relating to embodiment
1.
[0029] FIG. 2 is a plan view showing one example of a radial line
slot antenna used in the device of FIG. 1.
[0030] FIG. 3 is the results of a plasma ignition test relating to
the first embodiment, showing interdependence between microwave
power and chamber material.
[0031] FIG. 4 is the results of a plasma ignition test relating to
the first embodiment, showing interdependence between plating film
thickness and microwave frequency.
[0032] FIG. 5 is a cross section of a device relating to embodiment
1 showing the case where a plating layer is provided on an inner
surface of the chamber.
[0033] FIG. 6 is a cross section of a device relating to embodiment
1 showing the case where the inner surface of the chamber is
covered with a plate member comprising a prescribed material.
[0034] FIG. 7 is a cross section of a device relating to embodiment
2.
[0035] FIG. 8 is an enlarged view of region A in FIG. 7, and shows
a case where a first dielectric plate comes into contact with a
first O ring and a metallic thin film 114 is provided on a vacuum
sealing region.
[0036] FIG. 9 is an enlarged view of region A in FIG. 7, and shows
a case where the first O ring is enveloped by a metallic thin film
5.
[0037] FIG. 10 is a cross section of a device relating to
embodiment 3.
[0038] FIG. 11 is a graph showing the ion saturation current
density in embodiment 3.
[0039] FIG. 12 is a cross section of a device relating to
embodiment 4.
[0040] FIG. 13 is an enlarged view of region B in FIG. 12.
[0041] FIG. 14 is a graph showing the ion saturation current
density in embodiment 5.
[0042] FIG. 15 is a cross section of a device relating to
embodiment 7.
[0043] FIG. 16 is a schematic diagram of a tool for confirming the
presence or absence of plasma excitation in embodiment 7.
[0044] FIG. 17 is a graph showing a relationship between probe
voltage and probe current for embodiment 7.
[0045] FIG. 18 is a graph showing a relationship between minimum
discharge power and Ar pressure for embodiment 7.
[0046] FIG. 19 is a partial cross section of a device a device
relating to embodiment 8, and shows a case where a cover plate is
used.
[0047] FIG. 20 is a partial cross section of the device relating to
embodiment 8, and shows a case where a slot is reduced in size.
[0048] FIG. 21 is a graph showing the ion saturation current
density in embodiment 8.
[0049] FIG. 22 is a partial cross section of a device relating to
embodiment 9.
[0050] FIG. 23 is a partial cross section of a device relating to
embodiment 10.
[0051] FIG. 24 is a cross section of a device relating to
embodiment 11.
[0052] FIG. 25 is a cross section of a device relating to
embodiment 12.
[0053] FIG. 26 is a graph showing a relationship between deposition
rate of polymer film and chamber internal wall temperature.
[0054] FIG. 27 is a cross section of a device relating to
embodiment 13.
[0055] FIG. 28 is a schematic diagram showing a system when a
staged cooler method is adopted in collection and reuse of
fluorocarbon type gas in embodiment 14.
[0056] FIG. 29 is a graph showing a relationship between average
binding energy of fluorine gas and the plasma parameter of the
fluorine gas for embodiment 15.
[0057] FIG. 30 is a graph showing evaluation results of damage
caused by plasma irradiation of AlF.sub.3/MgF.sub.2 alloy, FIG.
30(a) showing before NF.sub.3 plasma irradiation and FIG. 30(b)
showing after 2 hours of NF.sub.3 plasma irradiation.
[0058] FIG. 31 is a graph showing distribution of ion saturation
current density for embodiment 16.
[0059] FIG. 32 is a graph showing distribution of electron
temperature for embodiment 16.
[0060] FIG. 33 is a graph showing distribution of electron
temperature for embodiment 16.
[0061] FIG. 34 is a schematic diagram of a system for measuring ion
current distribution for embodiment 16.
[0062] FIG. 35 is a schematic showing the structure of a single
probe used in measurement of electron temperature and electron
density for embodiment 16.
[0063] FIG. 36 is a graph showing results of plasma etching in
embodiment 17.
[0064] FIG. 37 is a schematic diagram showing a combination of a
cross section of elements of embodiment 18 and a element withstand
voltage measurement system.
[0065] FIG. 38 is a graph showing results of withstand voltage for
embodiment 18.
[0066] FIG. 37 is a graph showing results of analyzing chemical
binding state of a Si surface, using an X-ray photoelectron
spectroscope, for a silicon nitride film in embodiment 28.
[0067] FIG. 40 is a schematic diagram showing a combination of a
cross section of an element and an element dielectric breakdown
injection charge amount measurement system, for embodiment 28.
[0068] FIG. 41 is a graph showing results of dielectric breakdown
injection charge amount for embodiment 28.
[0069] FIG. 42 is a graph showing results of an X ray
diffractometer for embodiment 29.
[0070] FIG. 43 is a schematic diagram of a conventional magnetron
plasma etching device.
[0071] FIG. 44 is a schematic diagram showing an example of a
plasma device of the present invention.
[0072] FIG. 45 is a plan view showing an example of a plasma device
of the present invention.
[0073] FIG. 46 is a plan view showing an example of a plasma device
of the present invention.
[0074] FIG. 47 is a plan view showing an example of a plasma device
of the present invention.
[0075] FIG. 48 is a plan view showing an example of a plasma device
of the present invention.
[0076] FIG. 49 is a plan view showing an example of a plasma device
of the present invention.
[0077] FIG. 50 is a plan view showing an example of a plasma
treatment device of the present invention.
[0078] FIG. 51 is a plan view showing an example of a plasma
treatment device of the present invention.
[0079] FIG. 52 is a plan view showing an example of a plasma
treatment device of the present invention.
[0080] FIG. 53 is a plan view showing an example of a plasma device
of the present invention.
[0081] FIG. 54 is a plan view showing an example of a plasma device
of the present invention.
[0082] FIG. 55 is a drawing showing an example of means for
applying a high frequency to electrode II.
[0083] FIG. 56 is a drawing showing an example of means for
applying a high frequency to electrode II.
[0084] FIG. 57 is a graph comparing displacement in the related art
and this embodiment.
[0085] FIG. 58 is a drawing showing the manufacturing flow when
producing a pattern with this embodiment.
[0086] FIG. 59 is a graph comparing specific resistance in the
related art and this embodiment.
[0087] FIG. 60 is a schematic diagram showing a combination of a
cross section of elements of this embodiment and a withstand
voltage measuring system.
[0088] FIG. 61 is a graph showing results of measuring withstand
voltage for this embodiment and the related art.
[0089] FIG. 62 is a plan view of a plasma device of the related
art.
[0090] FIG. 63 is a graph showing distribution of film thickness
inside the surface of a wafer of silicon oxide film.
[0091] FIG. 64 is a schematic diagram showing a combination of a
cross section of elements of this embodiment and a system for
measuring dielectric breakdown injection charge amount.
[0092] FIG. 65 is a graph showing results of measuring dielectric
breakdown injection charge amount.
[0093] FIG. 66 is a graph showing distribution of film thickness
inside the surface of a wafer of direct nitride film.
[0094] FIG. 67 is a graph showing results of a system for measuring
barrier properties of a direct nitride film.
[0095] FIG. 68 is a graph showing a relationship between amounts of
oxygen and carbon, and total flow amount of process gas.
[0096] FIG. 69 is a drawing showing an example of a mask structure
for X ray lithography.
[0097] FIG. 70 is a schematic diagram showing a diamond thin film
permeability measurement system.
[0098] FIG. 71 is a graph showing the results of evaluating a
diamond thin film.
[0099] FIG. 72 is a graph showing dependence of surface roughness
of a polycrystalline silicon thin film on total flow amount.
[0100] FIG. 73 is a graph showing dependence of uniformity of a
glass substrate surface of a polycrystalline silicon thin film on
total gas flow amount.
[0101] FIG. 74 is a graph showing dependence of crystallite size of
polycrystalline silicon on total gas flow amount.
[0102] FIG. 75 is a graph showing dependence of the amount of
hydrogen in a polycrystalline silicon film on total gas flow
amount.
[0103] FIG. 76 is a graph showing dependence of the specific
resistance of polycrystalline silicon (P dopant) on total gas flow
amount.
[0104] FIG. 77 is a graph showing dependence of the in-plane
uniformity of a SiNx film on total gas flow amount.
[0105] FIG. 78 is a graph showing dependence of the withstand
voltage of a SiNx film on total gas flow amount.
[0106] FIG. 79 is a graph showing dependence of the atomic level
compositional ratio of Si to N in a SiNx film on total gas flow
amount.
[0107] FIG. 80 is a graph showing dependence of the deposition rate
of a fluorocarbon film on total gas flow amount.
[0108] FIG. 81 is a graph showing dependence of the deposition rate
of a fluorocarbon film on total gas flow amount.
[0109] FIG. 82 is a graph showing the dependence of additional gas
flow on the deposition rate of a BST film.
[0110] FIG. 83 is a graph showing the dependence of the in-plane
uniformity of wafer of a deposition rate of a BST film on
additional gas flow.
[0111] FIG. 84 is a cross section of a device manufactured using
the present invention.
[0112] FIG. 85 is a drawing showing process cluster tools for
formation of an insulating film and formation of tantalum
silicide.
[0113] FIG. 86 is a drawing showing distribution of a subthreshold
coefficient of a tantalum oxide gate insulation film MOSFET.
[0114] FIG. 87 is a graph showing initial damage rates of samples
of the present example and the related art.
[0115] FIG. 88 is a drawing showing in-plane uniformity of a
tantalum oxide capacitor.
[0116] FIG. 89 is a graph showing displacement of a turbo molecular
pump.
[0117] FIG. 90 is a plan view showing a practical example of a
plasma device of the present invention.
[0118] FIG. 91 is a plan view showing a practical example of a
plasma device of the present invention.
[0119] FIG. 92 is a plan view showing a practical example of a
plasma device of the present invention.
[0120] FIG. 93 is a drawing showing the layout of a wafer
conveyance port inside a wafer conveyance chamber of FIG. 90.
[0121] FIG. 94 is a drawing showing the layout of a wafer
conveyance port inside a wafer conveyance chamber of FIG. 90.
[0122] FIG. 95 is a drawing showing the layout of a wafer
conveyance port inside a wafer conveyance chamber of FIG. 90.
DESCRIPTION OF THE NUMERALS
[0123] 100 container
[0124] 101 chamber
[0125] 102 first dielectric plate
[0126] 103 waveguide dielectric plate
[0127] 104 object to be treated
[0128] 105 plasma
[0129] 106 antenna slot plate
[0130] 107 coaxial tube
[0131] 108 antenna guide
[0132] 109 electrode
[0133] 110, 110', 110", 111 slot
[0134] 112 plating layer
[0135] 113 plate member
[0136] 114, 115 metallic thin film
[0137] 116 second dielectric plate
[0138] 117 gas inlet
[0139] 118 means 8 for preventing warping of slot plate
[0140] 119 cover plate
[0141] 120 means 6 for maintaining antenna at fixed temperature
[0142] 121 means 7 for maintaining first dielectric plate at fixed
temperature
[0143] 122 means 9 for detecting presence or absence of plasma
generated in space 2
[0144] 123 window formed of material transparent to light
[0145] 124 light inlet
[0146] 125 Xe lamp
[0147] 201 radial line slot antenna
[0148] 202 first O ring
[0149] 205 space 3
[0150] 206 space 4
[0151] 207 space 5
[0152] 208 space 1
[0153] 209 space 2
[0154] 214 metallic thin film
[0155] 216 second O ring
[0156] 301 upper glass plate
[0157] 302 lower glass plate
[0158] 303 middle glass plate
[0159] 304 space 6
[0160] 305 tungsten wire
[0161] 306 aluminium wire covered with ceramic
[0162] 401 disk-shaped electrode
[0163] 402 pin
[0164] 403 aluminium wire
[0165] 404 resistor
[0166] 405 operational amplifier
[0167] 406 A-D converter
[0168] 407 computer
[0169] 408 stepping motor
[0170] 409 power supply
[0171] 501 chamber
[0172] 502 plasma
[0173] 503 object to be treated
[0174] 504 electrode
[0175] 505 heater
[0176] 506 laser
[0177] 507 photodetector
[0178] 601 probe tip
[0179] 602 silver wire
[0180] 603 ceramic tube
[0181] 604 SUS tube
[0182] 605 ring seal
[0183] 606 lobe measurement system
[0184] 701 object to be treated
[0185] 702 field oxidation film
[0186] 703 gate oxidation film
[0187] 704 gate electrode
[0188] 705 probe
[0189] 706 voltmeter
[0190] 707 voltage applying means
[0191] 801 object to be treated
[0192] 802 field oxidation film
[0193] 803 gate nitride film
[0194] 804 gate electrode
[0195] 805 probe
[0196] 806 voltmeter
[0197] 807 constant current source
[0198] 808 ammeter
[0199] 4301 vacuum container
[0200] 4302 electrode I
[0201] 4303 base
[0202] 4304 gas inlet
[0203] 4305 shower plate
[0204] 4306 dipole ring magnetron
[0205] 4307 bellows
[0206] 4308 porous plate
[0207] 4309 gate valve
[0208] 4310 base conveyance port
[0209] 4311 gas outlet
[0210] 4312 vacuum pump
[0211] 4313 matching circuit
[0212] 4314 high frequency power supply
[0213] 4406 vacuum container
[0214] 4407 electrode I
[0215] 4408 base
[0216] 4409 focus ring
[0217] 4410 shower plate
[0218] 4411 electrode II
[0219] 4412 gas inlet
[0220] 4413 magnetic field applying means
[0221] 4414 vacuum pump
[0222] 4415 matching circuit I
[0223] 4416 high frequency power supply I
[0224] 4417 matching circuit II
[0225] 4418 high frequency power supply II
[0226] 4501 vacuum container
[0227] 4502 gas inlet
[0228] 4503 magnetic field applying means
[0229] 4504 gas outlet
[0230] 4505 gate valve
[0231] 4601 vacuum container
[0232] 4602 gas inlet
[0233] 4603 magnetic field applying means
[0234] 4604 gas outlet
[0235] 4605 gate valve
[0236] 4701 vacuum container
[0237] 4702 gas inlet
[0238] 4703 magnetic field applying means
[0239] 4704 gas outlet
[0240] 4705 vacuum pump
[0241] 4706 gate valve
[0242] 4801 vacuum container
[0243] 4802 vacuum pump
[0244] 4901 vacuum container
[0245] 4802 vacuum pump
[0246] 5001 vacuum container
[0247] 5002, 5003 means for applying magnetic field inside the
container
[0248] 5004 electrode I
[0249] 5005 electrode II
[0250] 5006, 5007 means for expelling source material gas and
reaction product gas
[0251] 5004 electrode I
[0252] 5005 electrode II
[0253] 5006, 5007 means for expelling source material gas and
reaction product gas
[0254] 5108 means for applying a high frequency
[0255] 5204 electrode I
[0256] 5206, 5207 means for expelling source material gas and
reaction product gas
[0257] 5301 vacuum container
[0258] 5302 source material gas inlet
[0259] 5303 vacuum pump
[0260] 5304 dielectric plate I
[0261] 5305 antenna
[0262] 5306 electrode I
[0263] 5307 shower plate
[0264] 5308 base
[0265] 5309 reflector
[0266] 5301 vacuum container
[0267] 5302 electrode I
[0268] 5303 electrode II
[0269] 5404 target
[0270] 5405 base
[0271] 5406 matching circuit I
[0272] 5408 high frequency power source I
[0273] 5412 matching circuit II
[0274] 5413 high frequency power supply II
[0275] 5414 means for applying magnetic field
[0276] 5410 auxiliary electrode A
[0277] 5411 auxiliary electrode B
[0278] 5414a magnetic field applying means
[0279] 5415 vacuum pump
[0280] 5501 electrode IIa
[0281] 5502 electrode IIb
[0282] 5503 target
[0283] 5504 high frequency power supply I
[0284] 5505 matching circuit I
[0285] 5506 high frequency power supply II
[0286] 5507 matching circuit
[0287] 5508 phase control circuit
[0288] 5601 electrode IIa
[0289] 5602 electrode IIb
[0290] 5603 target
[0291] 5605 matching circuit
[0292] Best Mode of Practicing the Invention
[0293] (1) In the plasma device of the present invention, an
antenna for irradiating microwaves is provided on the outer side of
a container, with a first dielectric plate interposed between the
antenna and the container. Because the first dielectric plate is
made of a material that can transmit microwaves with almost no
loss, it becomes possible to excite plasma inside the container by
irradiating microwaves from outside the container, so that the
antenna is not directly exposed to the source material gas and the
reaction by-product gas. Also, an electrode for holding an object
to be treated is provided inside the container, and a microwave
emitting surface of the antenna and a surface of the object to be
treated that is to be subjected to plasma processing are arranged
opposite to each other and substantially in parallel, which means
that it is easy to reduce a space between these two surfaces, and
it is possible to increase the flow rate of source material gas and
reaction by-product gas, and to swiftly remove the reaction
by-product gas. Further, a wall section of the container other than
the first dielectric plate is either a member comprising a material
having specific conductivity higher than that of aluminium, or the
outside of this wall section is covered with the member, and if
thickness of the material is d, the specific conductivity of the
material is a, the magnetic permeability of the vacuum is
.mu..sub.0, and the angular frequency of microwaves radiated from
the antenna is .omega., the thickness d is larger than a skin depth
(invasion length) determined from
(2/.mu..sub.0.sigma..omega.).sup.1/2. This means that microwaves
introduced into the container are subjected to almost no loss, and
can be caused to propagate. As a result, plasma can be excited at a
low output, and stable plasma excitation becomes possible.
[0294] A first O ring having a function of a vacuum seal is located
between the inner surface of the first dielectric plate and the
wall section of the container, and by providing a member formed of
a conductive means as means I for preventing the first O ring from
being directly exposed to the microwaves radiated from the antenna
at least at a surface of the first dielectric plate coming into
contact with the O ring, leakage is prevented, and it is possible
to increase the service life of the O ring and reduce microwave
loss. In plasma devices using microwaves, leakage occurred easily.
The inventor of this application has been painstakingly searching
for the reason why leakage occurs easily when microwaves are used,
and has discovered that the cause lies with the o ring.
[0295] Specifically, the O ring absorbs microwave energy, with the
result that the O ring becomes overheated. Also, the surface
becomes molten. If the O ring overheats and the surface melts,
leakage will occur. The above describes the reason why leakage
occurs easily when microwaves are used, and the inventor of this
application was the first to discover this. In the case where
microwaves were used, it was not foreseen that the O ring would be
exposed to such high temperatures. It is possible to prevent
overheating of the O ring and melting of the surface due to the
provision of a thin film, formed of a conductive material (for
example a metallic material), on at least a surface of the first O
ring that comes into contact with the first dielectric layer. This
thin film formed of a conductive material can be provided by
applying a film on the first dielectric plate, and can be provided
by coating the dielectric film using painting, vapor deposition or
another method. As the conductive material, it is possible to use
titanium, for example.
[0296] Also, a thin film made of a conductive material is
preferably provided on the surface of the O ring. Titanium coating
can also be carried out in this case. Material having low
dielectric loss is preferably used in the O ring itself
constituting a foundation. For example, BAITON (Trade name) can be
used.
[0297] This thin film is preferably formed of a material having a
specific conductivity of at least 3.7.times.10.sup.7
.OMEGA..sup.-1.multidot.m.sup- .-1, and preferably has a thickness
of at least 10 .mu.m. By providing a thin film having such specific
conductivity and thickness, leakage is reduced still further, the
service life of the O ring is increased and it is possible to
provide a plasma device with low microwave loss.
[0298] A first O ring having a function of a vacuum seal is located
between the inner surface of the first dielectric plate and the
wall section of the container, and by providing means 2 for
preventing the first O ring from being directly exposed to the
microwaves radiated from the antenna on the surface of the first O
ring, it is possible to achieve a proposed leakage amount,
prolonged service life of the first O ring, and reduced microwave
loss.
[0299] By providing a second dielectric plate having a gas inlet
for substantially uniform supply of a desired gas between the first
dielectric plate and an electrode for holding the object to be
treated, it is possible to uniformly supply the source material gas
into the container, and to uniformly remove the reaction by-product
gas.
[0300] This second dielectric plate isolates the vacuum from the
atmosphere. Accordingly, the antenna does not reside in the vacuum.
If the antenna enters the vacuum, the antenna will be corroded, and
cooling is difficult.
[0301] A second O ring having a function of a vacuum seal is
located between the inner surface of the second dielectric plate
and the wall section of the container, and by providing means 3 for
preventing the second O ring from being directly exposed to the
microwaves radiated from the antenna on an inner surface or an
outer surface of the second dielectric plate, it is possible to
prevent leakage, prolong the service life of the second O ring, and
reduce microwave loss.
[0302] A second O ring having a function of a vacuum seal is
located between the inner surface of the second dielectric plate
and the wall section of the container, and by providing means 4 for
preventing the second O ring from being directly exposed to the
microwaves radiated from the antenna on the surface of the second O
ring, it is possible to prevent leakage, prolong the service life
of the second O ring, and reduce microwave loss.
[0303] By selecting a material having a dielectric loss angle tan
.delta. less than 10.sup.-3 as the material of the first dielectric
plate or the second dielectric plate, it becomes possible to cause
microwaves radiated from the antenna positioned outside the
container to be transmitted with virtually no loss, and it is
possible to achieve a reduction in microwave loss.
[0304] The frequency of the microwaves fed to the antenna is at
least 5.0 GHz, and if the distance of a space 1 between the first
dielectric plate and the second dielectric plate is less than 7 mm,
plasma excitation is not caused in the space 1, and there is no
generation of reaction by-products caused by discharge.
Accordingly, it becomes possible to avoid a phenomenon where
reaction by-products disturb the supply of source material gas. It
is also possible to prevent any detrimental affect on processes
such as formation of the thin film on the object to be treated,
nitriding or oxidation of the object to be treated, or etching of
the object to be treated, etc. by the reaction by-products.
[0305] By providing means 5 for generating a differential pressure
so that a pressure 1 of space 1 between the first dielectric plate
and the second dielectric plate is higher than a pressure 2 of
space 2 where an electrode for holding the object to be treated is
located, and is surrounded by the second dielectric plate and a
wall section of the container other than the second dielectric
plate, there is no generation of reaction by-products due to
discharge. The differential pressure can be easily provided by
varying the pressure of the source material gas and the degree of
vacuum inside the container.
[0306] By making the slots, positioned in a section where the
density of plasma generated in the space 2 is locally high, smaller
in diameter than the remaining slots, screening the slot, or not
providing the slot at all, the output power of the microwaves is
partially reduced in the slot plate functioning as a radiating
surface of the microwaves and it is possible to make the plasma
density more uniform. The position where the plasma density becomes
locally high is changed depending on device conditions etc., which
means, for example, that it is best to initially carry out trials
with the same slot diameter, and to find out the part where plasma
density becomes locally high using this test.
[0307] In the present invention, a space is formed between an
antenna and a first dielectric plate. In a plasma device of the
related art using microwaves (for example Japanese Patent laid-open
No. Hei. 8-111297) the antenna and the first dielectric plate are
stuck together. The antenna usually has a thickness in the region
of 0.3 mm, and is formed of a copper plate. However,
experimentation carried out by the present inventor indicates that
in the case of using microwaves the antenna reaches a high
temperature in the region of 150.degree. C., and the thickness of
the antenna is locally reduced accompanying expansion in due to the
heat. As a result, the radiating characteristics of microwaves from
the antenna change and the plasma become non-uniform.
[0308] In the present invention the antenna and the first
dielectric plate are not stuck together and a space is formed
between the two, which means that a spacer formed of an elastic
body touching the antenna can be interposed in this space, and
localized deflection of the antenna does not occur, even if there
is expansion due to heat, and it is possible to obtain a stable
plasma. It is possible to use, for example, silicon rubber, TEFLON
(trade name) etc. as the spacer formed of an elastic member.
[0309] Also, if means for supplying a heating medium is connected
to this space, a heating medium can be supplied into the space, and
it is possible to cool the antenna. By cooling the antenna it
becomes possible to prevent deflection of the antenna due to heat
without using the spacer. Obviously, it is also possible to cool
the antenna using the spacer.
[0310] Supply of the heating medium into the space formed by the
antenna and the first dielectric plate is one function of the means
6 for cooling the antenna, but besides the means 6 it is possible
to form a passage in an antenna guide, and to connect a line for
supplying a heating medium to this passage.
[0311] By providing means 7 for cooling the first dielectric plate
close to the first dielectric plate, source material gas to be
supplied can be supplied onto the surface of the object to be
treated while being maintained at a fixed temperature. Also, using
the means 7 bending of the slot plate is prevented, microwaves can
be radiated to the inside of the container with almost no loss and
it is possible to cause excitation of stable plasma.
[0312] By providing means 8 for preventing bending of the slot
plate, a highly efficient parallel beam of microwaves can be
radiated to the inside of the container which means that it is
possible to cause excitation of stable plasma.
[0313] By providing means 9 for detecting the presence or absence
of plasma generated in the space 2, it is possible to prevent the
inside of the container and the object to be treated etc, being
carelessly heated by microwaves radiated from the antenna, and to
thus prevent damage.
[0314] Since a structure is provided inside the container for
respectively raising the temperature of the container wall surface
and the outer part of the object to be treated to at least
150.degree. C., emitted gas that hinders the process is reduced,
and it is possible to prevent reattachment of reaction
by-products.
[0315] If a structure (for example a heater) for raising the
temperature within units constituting an exhaust system is provided
in the exhaust system, the temperature within the exhaust system is
raised by this structure and it is possible to prevent reaction
by-products being attached to internal walls of the units.
[0316] If a structure is provided for heating the object to be
treated, it is possible to compensate for insufficient energy
during plasma ion exposure by raising the temperature of the object
to be treated.
[0317] If a structure for carrying out recovery and recycling of
fluorocarbon type gas is provided downstream of the exhaust system,
it is possible to carry out recycling by adopting a staged cooling
system to gradually cool from a high boiling point gas through
liquefaction, distillation and purification to a liquid.
[0318] The inside of the container can be cleaned by causing
generation of a plasma inside the container having high ion radical
density and low plasma potential. The inside of the container at
this time can preferably be made of an alloy exhibiting extremely
good plasma resistance (AlF.sub.3/MgF.sub.2).
[0319] By providing an electrode having the function of holding the
object to be treated with means for applying a d.c. bias and/or and
a.c. bias, it is possible to increase the ion energy radiated to
the object to be treated. For example, when adopted plasma etching,
it is possible to realize high speed etching with good
uniformity.
[0320] Using the plasma device of the present invention, it is
possible to uniformly carry out etching processing, direct
oxidation processing and direct nitriding processing on the surface
of an object to be treated having a large surface area, and uniform
film formation at low temperature and high speed is possible.
[0321] (2) FIG. 44 is a schematic drawing showing an example of a
plasma device of the present invention. FIG. 44(a) is a plan view
looking from above the device, while FIG. 44(b) is a cross section
through line A-A in FIG. 44(a).
[0322] In FIG. 44, reference numeral 4406 is a vacuum container,
reference numeral 4407 is an electrode I, reference numeral 4408 is
a substrate, reference numeral 4409 is focus ring, reference
numeral 4410 is a shower plate, reference numeral 4411 is an
electrode II, reference numeral 4412 is a gas inlet, reference
numeral 4413 is magnetic field applying means, reference numeral
4414 is a magnetic pump, reference numeral 4415 is a matching
circuit I, reference numeral 4416 is a high frequency power supply
I, reference numeral 4417 is a matching circuit II and reference
numeral 4418 is a high frequency power supply II.
[0323] In the plasma device of FIG. 44, a dipole ring magnet having
a plurality of permanent magnets aligned in an annular shape are
used as magnetic field applying means 4413, as shown in the
drawing. The permanent magnets constituting the dipole ring magnet
are aligned so that a direction of magnetization passes through one
rotation as the magnet positions go halfway round.
[0324] Gas introduced from the gas inlet 4412 is discharged into a
process space from a plurality of small holes of the shower plate
4410. This introduced gas, and reaction product gas discharged from
a substrate surface, is expelled from a plurality of vacuum pumps
4414 to the outside via a space interposed between the magnetic
field applying means 4413a and 4413b to the side of the substrate.
A comparatively wide space is provided in an upper part of the
vacuum pump 4414 so as to cause the gas conductance to be lowered.
A projection surface of the upper section of the vacuum container
4406 is shown in FIG. 44(a). The vacuum container 4401 has a shape
close to a square, and four vacuum pumps 4402 are provided in the
corners of this vacuum container 4401. In this way, if exhaust is
carried out by a plurality of vacuum pumps aligned around the
substrate substantially axisymmetrical to an axis perpendicular to
the substrate surface and running through the center of the
substrate, uniform gas flow can be realized in a rotational
direction above the substrate, without causing hardly any lowering
of gas conductance. That is, it becomes possible to cause a large
amount of gas to flow up to a value close to the tolerance of the
vacuum pump, and it is possible to handle an ultra high speed
process for a large diameter substrate.
[0325] Here, the electrode II 4411 is a ring shaped metallic plate,
and is provided so as to allow improvement of in-plane uniformity
of plasma close to the surface of the substrate 4408. High
frequency power output from the high frequency power supply II 4418
is applied to the electrode II 4411 through the matching circuit II
4417. If a balance of electron drift on the surface of the
electrode II 4411 and the electron drift on the surface of the
substrate 4408, caused by a magnetic field applied by application
of appropriate high frequency power to the electrode II 4411, is
obtained, plasma close to the surface of the substrate 4408 is made
almost totally uniform. If uniformity of the plasma surface close
to the surface of the substrate 4408 is good with application of
high frequency to the electrode II 4411, or if no problem arises
even with non-uniformity, it is not particularly necessary to
provide the electrode II 4411.
[0326] In the plasma device of FIG. 43, the shower plate 405 is
grounded, but it does not necessarily need to be grounded and it
does not matter if a high frequency is applied. Also, it does not
matter of a shower plate is not used and gas is discharged from
another section.
[0327] FIG. 45 is a plan view showing an example of a plasma device
of the present invention. Reference numeral 4501 is a vacuum
container, reference numeral 4502 is a gas inlet, reference numeral
4503 is magnetic field applying means, reference numeral 4504 is a
gas outlet, and reference numeral 450005 is a gate valve. A surface
of the vacuum container 4501 projecting from an upper part is
approximately triangular in shape, and three vacuum pumps are
place-din the corner sections. Other aspects of the plasma device
are the same as that described for FIG. 44. With the plasma device
of FIG. 45, a distance between a gate valve 4505 and the substrate
is smaller than in the plasma device shown in FIG. 44. This is
suitable for the case when the stroke of a substrate conveyance arm
is restricted.
[0328] FIG. 46 is a plan view showing an example of a plasma device
of the present invention. Reference numeral 4601 is a vacuum
container, reference numeral 4602 is a gas inlet, reference numeral
4603 is magnetic field applying means, reference numeral 4604 is a
gas outlet, and reference numeral 4605 is a gate valve. Two vacuum
pumps are placed in the vacuum container 4602. Apart from this, the
plasma device is the same as that described in FIG. 44. With the
plasma device of FIG. 46, similarly to the device of FIG. 45, a
distance between a gate valve 4505 and the substrate is smaller
than in the plasma device shown in FIG. 44. This is suitable for
the case when the stroke of a substrate conveyance arm is
restricted and when there is a margin in the expel capacity of the
vacuum pump.
[0329] FIG. 47 is a plan view showing an example of a plasma device
of the present invention. Reference numeral 4701 is a vacuum
container, reference numeral 4702 is a gas inlet, reference numeral
4703 is magnetic field applying means, reference numeral 4704 is a
gas outlet, reference numeral 4705 is a vacuum pump, and reference
numeral 4706 is a gate valve. Two vacuum pumps are placed sideways
in the vacuum container 4702. Apart from this, the plasma device is
the same as that described in FIG. 44. The footprint of the plasma
device including the vacuum container 4701 and the vacuum pump 4705
is larger, but the size of the vacuum container 4701 becomes a
minimum. This is suitable for the case when the stroke of a
substrate conveyance arm is restricted and when there are
restrictions on the size of the vacuum container.
[0330] In the plasma device of FIG. 48, a four vacuum pumps 4802
are respectively provided in each of upper and lower sections of
the vacuum container 4801, making eight vacuum pumps in total. In
this way, if the number of vacuum pumps is increased, the load
imposed on each vacuum pump is reduced and the vacuum pumps can be
made smaller, which means that it is possible to make the footprint
of the plasma device smaller. Remaining sections are the same as in
the description for FIG. 44.
[0331] The plasma device of FIG. 49 has corners of the upper
section of the vacuum container 4901 rounded off. Within a space
inside a vacuum container 4901 above the vacuum pump 4902,
unnecessary portions where gas flow is slow are reduced in size,
which means that the atmosphere within the vacuum container 4901 is
further purified.
[0332] FIG. 50 is a plan view showing an example of a plasma
processing device of the present invention. Means for applying a
magnetic field inside a container 5002 and 5004 are provided
outside a vacuum container 5001. Since the means 5002 and 5003 are
divided top and bottom, the substrate can be conveyed without
having to move an electrode I 5004 for mounting the substrate to be
processed up and down. The plate type electrode I 5004 is parallel
to a plate type electrode II 5005, which is electrically grounded,
and provided with a shower plate as means for introducing source
material gas. Reference numerals 5006 and 5007 are means for
expelling reaction product gas, and are configured so that the gas
is discharged to the outside through a space formed between the
magnetic field applying means 5002 and 5003.
[0333] FIG. 51 is a plan view showing an example of a plasma
processing device of the present invention. A plate type electrode
I 5104 is parallel to a plate type electrode II 5105 which is
connected to means 5108 for applying a high frequency independently
of electrode I, and has a shower plate as means for introducing
source material gas. Reference numeral 5106 and 5107 are means for
expelling source material gas and reaction product gas to the
outside.
[0334] FIG. 52 is a plan view showing an example of a plasma
processing device of the present invention. An electrode I 5204 is
provided, and there is a shower plate as means for introducing
source material gas. Reference numerals 5206 and 5207 are means for
expelling source material gas and reaction product gas, and are
constructed to discharge gas to the outside.
[0335] The plasma device of FIG. 53 has a vacuum container 5301, a
source material gas inlet 5302 required to generate plasma inside
the container, and a vacuum pump 5303 for expelling source material
gas that has been introduced into the container. Part of a wall
section constituting the container is a dielectric plate I 5304
formed of a material capable of transmitting microwaves with
substantially no loss, and an antenna 5305 for radiating microwaves
and an electrode I 5306 for mounting a substrate 5308 to be
processed inside the container are provided outside the container,
sandwiching the dielectric plate I. The microwave radiating surface
of the antenna and a surface of the substrate that is to be plasma
treated are arranged opposite each other and substantially
parallel. Here, conveying of radiated microwaves to the outlet side
is prevented, and a reflector 5309 is preferably provided only
above the substrate, for the purpose of causing uniform plasma
generation.
[0336] Also, the electrode I for mounting the substrate can be
grounded, or it is also possible to provide means for applying a
d.c. bias or an a.c. bias. Further, in order to make introduction
of source material gas uniform and to swiftly remove reaction
product gas, the source material gas of this device is introduced
from a plurality of small holes through a shower plate 5307 to a
process space. This source material gas and reaction product gas
are expelled to the outside by a plurality of vacuum pumps 5303. A
comparatively wide space is provided in an upper section of each
vacuum pump so as not to cause lowering of the gas conductance. In
this way, if gas is expelled from a plurality of vacuum pumps
aligned substantially equal distances apart to the side of the
substrate, it is possible to realize gas flow above the substrate
uniform in a rotational direction without lowering the gas
conductance hardly at all. That is, it becomes possible to cause a
large amount of gas to flow close to the capacity of the vacuum
pump, and it is possible to handle ultra high speed processing of
large diameter substrates.
[0337] The plasma device of FIG. 54 is provided with two parallel
plate type electrodes electrode I 5402 and electrode II 5403 inside
the vacuum container 5401. A gate valve 5404 and a substrate 5405
on which a film is to be deposited are respectively mounted on the
electrode II and the electrode I. Source material gas is then
introduced into the container, and matching circuit I 5406,
matching circuit II 5412, high frequency power supply I 5408 and
high frequency power supply II 5413 are connected for the purpose
of applying high voltage to the electrode I and the electrode II.
Means 5414 for applying a magnetic field to at least a target
surface is provided outside the container. An auxiliary electrode A
5410 is provided at a region further out than the outer edge of the
target for the purpose of making the density of plasma generated
close to the surface of the target uniform. Means for adjusting a
junction impedance provided at a portion electrically connected to
the electrode II is attached to the auxiliary electrode A 5410. At
the region further out than the outer edge of the target, an
auxiliary electrode B 5411 for applying a high frequency power
separately and independently of a high frequency applied to the
electrodes I and II is provided at a position separated from the
substrate and electrode II, also for the purpose of making the
density of plasma generated close to the surface of the target
uniform. However, as an alternative to providing the auxiliary
electrode B it is possible to employ a method for relieving plasma
deviation caused by the magnetic field, by making the pressure
inside the container at the time of plasma generation a high
pressure (1--several tens of Torr). Further, even if the auxiliary
electrode A or auxiliary electrode B is not provided, there is no
need to specially provide the auxiliary electrode A and B in cases
such as when in-plane uniformity of plasma close to the surface of
the substrate is satisfactory, or where no problem occurs even with
non-uniformity. The gas that has been introduced into the container
passes through means 5414a and 5414B for applying a magnetic field
to the side of a substrate and is discharged to the outside from a
plurality of vacuum pumps 5415. At an upper portion of the vacuum
pumps, there is provided a comparatively wide space so as to
prevent lowering of the gas conductance. Also, it does not matter
if the arrangement of the vacuum pumps is the same as that shown in
FIG. 45-FIG. 49. It is also permissible to use another magnetic
field applying means for applying the magnetic field. In this
plasma device, plasma density is raised using a magnetic field, but
there is no problem in using other means, and it is permissible to
not use anything when there is no need to raise plasma density.
[0338] Still further, the electrode II being the electrode for
holding the target can be divided into two equal halves, with a
high frequency being respectively applied to the divided halves.
However, the phases of the two high frequencies at this time are
180.degree. out of phase with each other and it is necessary to
provide means so that discharge does not occur between electrode
11a and electrode 11b. However this method is restricted to when
the target is an insulating material, and when the target is
conductive the substrate itself must be divided to match up with
the electrode II. By using this method, since it becomes possible
to keep the plasma potential low, the ion collision energy to the
target can be reduced and it is confirmed that better quality films
can be formed. It is also possible to use either of the following
two methods as means of applying to the electrode II.
[0339] (a) FIG. 55 shows a first method. A high frequency power
supply I 5504, matching circuit I 5505, high frequency power supply
II 5506 and matching circuit II 5507 are connected to divided
electrodes Ia 5501, electrode IIb 5502, for respectively applying a
high frequency to the target 5503, electrode IIa and electrode IIb,
and the phases of the two high frequencies are made opposite and
introduced by connecting a phase adjustment circuit 5508 to the
electrode IIb side.
[0340] (b) FIG. 56 shows a second method. Reference numeral 5501
represents a divided electrode Ia. reference numeral 5502
represents electrode IIb and reference numeral 5503 represents a
target. High frequency oscillations from the high frequency power
supply 5504 propagate to the matching circuit 5505 and are grounded
through a balanced/non-equilibrium circuit (balance). Using this
circuit high frequency having mutually reversed phase is
introduced.
[0341] (3) Taking FIG. 53 as an example, the plasma device of the
present invention is provided with the exhaust space 5315 formed
directly contacting the intake port 5314 of the vacuum port 5303,
to the side of the film forming space 5313 above a substrate
5308.
[0342] By providing the exhaust space 5315, being a comparatively
wide space, to the side of the film forming space 5313, source
material gas that has been introduced from outside, or reaction
product gas, is expelled without lowering the gas conductance, and
it is possible to make a large amount of gas flow, close to the
capacity of the vacuum pump.
[0343] This exhaust space 5315 is preferably provided at a number
of places, and in this case the spaces are preferably arranged at
positions symmetrical around the substantial center of the
substrate 5308. If a plurality of such spaces are symmetrically
provided, the above described effects are even more remarkable.
[0344] The height b of the exhaust space 5315 is preferably as
large as is practicable.
[0345] The width L of the exhaust space 5315 is preferably at least
two times the height a of the film formation space 5313. The
uniformity of the gas flow is dramatically improved by the fact
that the width L is two times the height a.
[0346] Embodiments
[0347] A plasma device of the present invention will be described
in the following, with reference to the drawings, but the present
invention is not limited to these embodiments.
[0348] (Embodiment 1)
[0349] In this embodiment, when plasma is generated by introducing
microwaves into a container using the plasma device shown in FIG.
1, the plasma stability is examined by varying the material of a
member constituting an inner surface of the container, and the
width of the member.
[0350] In FIG. 1, reference numeral 100 is a container capable of
having its internal pressure reduced, reference numeral 101 is a
chamber, reference numeral 102 is a first dielectric plate,
reference numeral 103 is a waveguide dielectric plate, reference
numeral 104 is an object to be treated, reference numeral 105 is
plasma, reference numeral 106 is an antenna slot plate, reference
numeral 107 is a coaxial tube, reference numeral 108 is an antenna
guide, reference numeral 109 is an electrode, reference numeral 110
is a slot, reference numeral 201 is a radial line slot antenna,
reference numeral 202 is a first O ring, reference numeral 205 is a
space 3, reference numeral 206 is a space 4 and reference numeral
207 is a space 5.
[0351] In FIG. 1, the container capable of having the internal
pressure reduced 100 comprises a chamber 101 (material: SUS), a
first dielectric plate 102 (material: quartz), and first O ring 202
functioning as a seal between the chamber 101 and the dielectric
plate 102. The inside of the container 100 can be decompressed by
an exhaust system, not shown, and the container 100 itself is
electrically grounded.
[0352] A radial line slot antenna 201, comprising the antenna guide
108 (material: Al), the antenna slot plate 106 (material: Cu) and
the waveguide dielectric plate 103 (material: quartz), is located
outside the container 100. Microwaves are introduced into the
antenna 201 through the coaxial tube 107 (material: Cu), conveyed
in a radial direction while leaking out from each slot 110 provided
in the antenna slot plate 106, and radiated to the inside of the
container 100. Gas is made to flow into the container 100 from a
source material gas supply system, not shown, and plasma 105 is
excited. There is an electrode 109 having the function of holding
an object to be treated 104 inside the container 100, and the
electrode 109 is located so that it is parallel to and opposite the
antenna 201 and functions to heat the object to be treated. Also,
the electrode 109 is capable of being made to move upwards and
downwards from outside the container 100, and the distance from the
first dielectric plate 102 can be varied from approximately 10 mm
to 60 mm.
[0353] FIG. 2 is a schematic plan view of the radial line slot
antenna 201 shown in FIG. 1 looking from above. Hole sections
(hereafter referred to as slots) 110 penetrating through antenna
slot plate 106 are arranged in the slot plate, but the arrangement
of the slots 110 is not limited to that shown in FIG. 2.
[0354] The slots 110 are configured having two slots 111a and 111b
constituting a single pair, and the two slots in a pair are
arranged at right angles to each other at a distance of a quarter
of a wavelength kg of an incident wave passing through the coaxial
tube 107 to the antenna 201. The pairs comprised of a slot 11a and
a slot 11b, namely the slots 110, are each capable of outputting
circularly polarized electromagnetic waves, and a plurality of
slots 110 are numerously concentrically provided. Besides the
concentric arrangement the slots 110 can also be arranged spirally.
Although this embodiment is not limited to this concentric
arrangement, the slots 110 are provided in this way so as to
uniformly radiate electromagnetic waves within a large surface
area.
[0355] The present invention is not limited to radiation of
concentrically polarized electromagnetic waves, and it is possible
to use linear polarization, but concentric polarization is
preferred.
[0356] Reference numeral 107 is a coaxial tube for supplying
microwaves to the antenna slot plate 106, and is connected to a
microwave power supply through a coaxial tube--waveguide converter,
not shown, a waveguide and a matching circuit.
[0357] There is also a need for means for conveying the object to
be treated 104 into and out of the chamber 101, but this is omitted
from FIG. 1.
[0358] In this example, microwaves (frequency=8.3 GHz) are
introduced to the radial line slot antenna 201 using the coaxial
tube 107, electromagnetic waves are radiated from the antenna 201
and plasma 105 is excited inside the space 5 of the chamber 100.
However, There was no excitation of plasma 105 within the space 5
(207) with the SUS chamber 101.
[0359] Accordingly, plating layers (7) comprising lead, tantalum,
tungsten, aluminium, gold, copper and silver are coated on an inner
surface of the SUS chamber 101 and the above described plasma
ignition test was carried out. At this time, as the process gas Ar
gas was used, and gas pressure was 500 mTorr.
[0360] FIG. 3 shows the results of the plasma ignition test. At
this time, the thickness of the plating needs to be thicker than a
skin depth determined from d=(2/.mu..sub.0.sigma..omega.).sup.1/2
of the microwaves, which means about 10 .mu.m. From FIG. 3, it is
understood that if the specific conductivity of the material of the
inner surface of the chamber 101 is made high, then it is easy for
plasma excitation to take place. The results of this test show that
at the instant microwaves are introduced into the container 100 the
container starts to act as a resonator, and since a strong electric
field is required in the plasma ignition test the q value of the
resonator must be made high.
[0361] FIG. 4 shows results when an aluminium plating layer is
provided on the inner surface of the SUS chamber 101 and a plasma
ignition test is carried out by varying the thickness of the
plating layer and the wavelength of microwaves introduced to the
antenna 201. From FIG. 4 it can be confirmed that at the time when
the thickness of the aluminium plating layer is thicker than a skin
depth of 1.67 .mu.m determined from microwave
d=(2/.mu..sub.O.sigma..omega.).sup.1/2, in the case of the
frequency of the microwaves being 2.45 MHz, and that at the time
when the thickness of the aluminium plating layer is thicker than a
skin depth of 0.89 .mu.m determined from microwave
d=(2/.mu..sub.O.sigma..omega.).sup.1- /2, in the case of the
frequency of the microwaves being 8.3 MHz, plasma is stable.
[0362] Here, .mu..sub.O is permeability of vacuum, .sigma. is
conductivity of the material in question, and .omega. is the
angular frequency of the microwaves.
[0363] From the results described above, the following points
become clear.
[0364] 1) When the material of the member constituting the inner
surface of the container is SUS, conductor loss is large and
ignition is difficult.
[0365] 2) By replacing the material of the member constituting the
inner surface of the container for high conductivity material, the
Q value of the resonator becomes comparatively high and the problem
of difficult ignition does not arise.
[0366] 3) When a material having conductivity of at least the
conductivity of aluminium
(3.7.times.10.sup.7[.OMEGA..sup.-1.multidot.m.sup.-1]) is used as
for the inner surface of the chamber 101, the plasma becomes
stable, and copper, gold, silver etc. are suitable as such as
material.
[0367] A device incorporating the above results can be as shown in
FIG. 5 and FIG. 6.
[0368] The device of FIG. 5 differs from the device in FIG. 1 in
that an aluminium plating film 112 is coated to a thickness of 10
.mu.m on the inner surface of the SUS chamber 101. The device of
FIG. 6 is different from the device of FIG. 1 in that it uses a
plate member 113 comprised of the above described material (having
a thickness greater than the skin depth determined from the
microwaves) and the inner surface of the chamber is covered. It can
be confirmed that the devices of FIG. 5 and FIG. 6 are the same
with respect to plasma stability.
[0369] (Embodiment 2)
[0370] In this embodiment, the device of FIG. 5 is different from
embodiment 1 in that a metallic thin film 114 is provided at a
vacuum seal region where the first dielectric plate 102 (material:
quartz) contacts a first O ring 202, as shown in FIG. 7, and the
first O ring is not exposed to electromagnetic waves radiated from
the antenna slot plate 106. Fluorine type resin is used as the
material for the first O ring.
[0371] FIG. 8 is an enlarged view of region A in FIG. 7, and shows
the case where the metallic thin film 114 is provided at a vacuum
seal region where the first dielectric plate 102 (material: quartz)
contacts a first O ring 202.
[0372] When the first O ring is made of a material such as resin
that absorbs microwaves, it is directly heated by electromagnetic
waves radiated from the antenna slot plate 106m as a result of
discharge over a long time and it will be understood that damage
will occur.
[0373] Therefore, metallic thin films each having a thickness of 10
.mu.m and respectively being aluminium, nickel, and copper are
provided at the vacuum seal region where the first dielectric plate
102 contacts the first O ring 202, as the metallic thin film 114.
This thickness of 10 .mu.m was validated in embodiment 1, and is a
thickness value larger than the skin depth determined from
microwave d=(2/.mu.O.sigma..omega.).sup.1/- 2 that can sufficiently
reflect microwaves. A durability test of the first O ring 202 was
carried out using a device provided with this type of metallic thin
film 114. The results showed that when nickel
(conductivity:1.4.times.10.sup.6[.OMEGA..sup.-1.multidot.m.sup.-1])
was used, conductivity was low so microwaves were not sufficiently
reflected, the power of the microwaves was subject to heat loss and
the first O ring was excessively heated and damaged after a
discharge time of 2-3 hours. On the other hand, in the case where a
comparatively high conductivity material such as aluminum
(conductivity:3.7.times.10.sup.7[.OMEGA..sup.-1-
.multidot.m.sup.-1]) or copper
(conductivity:6.0.times.10.sup.6[.OMEGA..su-
p.-7.multidot.m.sup.-1]) was used, damage to the first O ring could
not be confirmed even after a discharge time of 100 hours.
[0374] Consequently, it has been found that the metallic film 114
should have high conductivity and high adhesion to the first
dielectric plate 102. It also goes without saying that it is
necessary for the thickness of the metallic thin film 114 to be
thicker than the skin depth determined from microwave
d=(2/.mu..sub.O.sigma..omega.).sup.1/2.
[0375] FIG. 9 is an enlarged view of region A in FIG. 7 and shows
the case where in place of the metallic thin film 114 the first O
ring 202 itself is coated with a metallic thin film 115 having the
same function as the metallic thin film 114 provided in the first
dielectric plate 102. In this way, by also coating the first O ring
202 itself with the metallic thin film 115 the same effects as for
the device of FIG. 8 can be obtained. Also in the case where the
first O ring 202 is made of metal, the above problem is solved.
[0376] (Embodiment 3)
[0377] In this embodiment, as shown in FIG. 10, a device provided
with a second dielectric plate 116, having a gas inlet 117 for
supplying desired gas in a substantially uniform manner provided
between the first dielectric plate 102 and the electrode 109 for
holding the object to be treated 104, was used, and the uniformity
of plasma 105 generated in the space 2 (109) was examined.
[0378] FIG. 10 shows the device incorporating the results of the
second embodiment, and aluminum (Al) was coated to a thickness of
10 .mu.m as a metallic thin film 114, at a region for vacuum
sealing where the first dielectric plate 102 comes into contact
with the first O ring 202. AlN (aluminium nitride) was used as the
second dielectric plate 116 shown in FIG. 10. Since aluminium
nitride contains nitrogen, it is characterized by the fact that
there is less discharge gas compared to quartz.
[0379] In the device of FIG. 10, Ar gas was introduced into space 1
(208) as a plasma gas, and uniformity of plasma 105 generated in
the space 2 (209) as a result of introducing microwaves to the
antenna 201 was evaluated in order to study the ion saturation
current density. At this time, the gas pressure of the space 2
(209) was 50 mTorr, and the power of microwaves input to the
antenna 201 was 1600W.
[0380] FIG. 11 is a graph showing the results of studying saturated
electron current density. In FIG. 11, the mark .box-solid.
represents the case when the second dielectric plate 116 having the
gas inlet 117 is provided, the mark .circle-solid. represents the
case where the second dielectric plate 116 is not provided, and the
mark .tangle-solidup. represents the case where the second
dielectric plate 116 is provided without the gas inlet 117.
[0381] From FIG. 11 is will be understood that by providing the
second dielectric plate 116 having the gas inlet 117 the plasma is
made uniform. In the case where the gas inlet 117 is not provided
(mark .tangle-solidup.) there is no reaction accelerator for
causing plasma excitation inside the container [namely the space 2
(209)), which obviously means that there will be no plasma
excitation.
[0382] By providing this type of second dielectric plate 116 it is
possible to supply source material gas uniformly onto a surface of
an object to be treated 104 having a diameter greater than 300 mm
which was impossible in the related art, and it is also possible to
uniformly remove generated reaction by-product gas from the object
to be treated 104.
[0383] With the above described second dielectric plate 116, gas
inlets 117 are arranged so that there are an equal number per unit
surface area, but this arrangement is not limiting and it is
possible to arrange them as conditions demand.
[0384] (Embodiment 4)
[0385] In this embodiment, the plasma device of FIG. 10 is provided
with a metallic thin film 214 at a region for vacuum sealing where
the second dielectric plate 116 (material: aluminium nitride) comes
into contact with the second O ring 216, and the effect of
preventing the second O ring 216 being exposed to electromagnetic
waves radiated from the antenna slot plate 106 was evaluated.
Aluminium (Al) having a thickness of 10 .mu.m was used as the
metallic thin film 214, and fluorine type resin was sued as the
second O ring 216.
[0386] FIG. 13 is an enlarged view of region B in FIG. 12.
[0387] Apart from this point, embodiment 4 is the same as
embodiment 2.
[0388] Similarly to embodiment 2, the extent of damage to the
second O ring 216 was evaluated. These results show that in the
case where the metallic thin film 214 is provided, similarly to the
case where the metallic thin film 114 of embodiment 2 is provided,
there was no damage to the second O ring 216 even after a discharge
time of 100 hours.
[0389] Also, similarly to the first O ring 202 shown in FIG. 9, the
second O ring 216 shown in FIG. 10 can be itself covered with a
metallic thin film 115 having a similar function to the 114
provided on the second dielectric plate 116, and it was confirmed
that this had the same effect as when the above described metallic
thin film 214 was provided.
[0390] (Embodiment 5)
[0391] With this embodiment, in the plasma device of FIG. 12
materials having a different dielectric loss angle are used as the
first dielectric plate 102, and the density (ion saturation
current) of plasma generated in the space 2 (209) was
evaluated.
[0392] As materials having a different dielectric loss angle for
constituting the first dielectric plate 102, Bakelite (BM-120,
dielectric loss aangle=0.044), glass (corning #0010 dielectric loss
aangle=0.006), AIN (dielectric loss aangle=0.001), and SiO.sub.2
(dielectric loss aangle=0.0001) were used. At this time, the
material constituting the second dielectric plate 116 was AIN.
[0393] Apart from this point, embodiment 5 was the same as
embodiment 2.
[0394] FIG. 14 is a graph showing results of measuring the ion
saturation current. It will be understood from FIG. 14 that since
electrical loss becomes small and microwave power is supplied to
the container without loss with decrease in the dielectric loss
angle tan.delta., the plasma density(ion saturation current)
increases. Particularly, it will be understood that when a material
having dielectric loss angle tan .delta. of less than 10.sup.-3 is
used as the first dielectric plate 102, it is possible to obtain
plasma having a high ion saturation current of 12 mA/cm.sup.2. This
means that it is preferable to have a material with a lower
dielectric loss angle tan .delta. as the material for the first
dielectric plate 102, for example, quartz (SiO.sub.2) or aluminium
nitride (AlN) having tan .delta. of less than 10.sup.-3.
[0395] (Embodiment 6)
[0396] With this embodiment, in the plasma device of FIG. 12
materials having a different dielectric loss angle are used as the
second dielectric plate 116, and the density (ion saturation
current) of plasma generated in the space 2 (209) was
evaluated.
[0397] As materials having a different dielectric loss angle for
constituting the second dielectric plate 116, Bakelite (BM-120,
dielectric loss angle=0.044), glass (corning #0010 dielectric loss
angle=0.006), AIN (dielectric loss angle=0.001), and SiO.sub.2
(dielectric loss angle=0.0001) were used. At this time, the
material constituting the second dielectric plate 116 was
quartz.
[0398] Apart from this point, embodiment 6 was the same as
embodiment 5.
[0399] Substantially the same effects as in FIG. 14 are also
obtained with this embodiment. That is, it can be understood that
when a material having a dielectric loss angle tan .delta. of less
than 10.sup.-3 is used for the second dielectric plate 116, plasma
having a high ion saturation current of greater than 12 mA/cm.sup.2
can be obtained.
[0400] However, there is a need to provide gas inlets 117 in the
second dielectric plate 116, and a requirement to use a material
with satisfactory manufacturing precision. Accordingly, it is
possible to use quartz (SiO2) or aluminium nitride (AlN) having tan
.delta. of less than 10.sup.-3 as the material of the second
dielectric plate 116, but it is preferable to use aluminium nitride
(AIN) from the point of view of manufacturing precision.
[0401] (Embodiment 7)
[0402] With this embodiment, in the plasma device shown in FIG. 15,
in order to study conditions where plasma excitation does not take
place in the space 1 (208) between the first dielectric plate 102
and the second dielectric plate 116, the following experiment was
carried out.
[0403] FIG. 15 is a drawing in which pressure P1 of the space 1
(208), pressure P2 of the space 2 (209) and the distance tg between
the first dielectric plate 102 and the second dielectric plate 116
have been added to the drawing showing the device of FIG. 12.
[0404] FIG. 16 is a schematic drawing of a jig used to observe
whether or not there is plasma excitation in the space 1 (208). The
jig of FIG. 16 is located directly below the first dielectric plate
102 (material: quartz) being part of the container 100 of the
plasma device in FIG. 1. In FIG. 16, reference numeral 301 is an
upper glass plate, reference numeral 302 is a lower glass plate,
reference numeral 303 is a middle glass plate, reference numeral
304 is a space 6, reference numeral 305 is a tungsten wire, and
reference numeral 306 is an aluminium wire coated with
ceramics.
[0405] The jig of FIG. 16 has two glass plates (301 and 302) of 2
mm in thickness fixed a distance tg apart. A side section of the
space 6 (304) formed by the two glass plates (301 and 302) is
covered by a separate glass (303) so that plasma does not penetrate
inside the space 5 of width tg. Since the inside of the space 6
(304) is not airtight, gas penetrates and the pressure inside the
space 6 (304) becomes almost the same as the pressure inside the
container.
[0406] In order to confirm whether or not plasma is generated
inside the space 6 (304), two probes (305a and 305b) are inserted
into the gap. The probes (305a and 305b) are tungsten of diameter
0.1 mm .phi. and length 8 mm. The probes (305a and 305b) are heated
if they are irradiated with microwaves, so the outer surface of
glass at the edges of the probes (305a and 305b) was sealed with
copper plate (not shown in the drawing). A variable voltage was
applied between the two probes (305a and 305b) in an electrically
floating state, and the current flowing was measured using a
multimeter.
[0407] FIG. 17 is a graph showing a relationship between probe
voltage and probe current observed when the variable was applied
between the two probes (305a and 305b). The curve (a) of FIG. 17
shows the a current voltage characteristic that is symmetrical to
the left and right in the case where plasma was generated inside
the space 6 (304). On the other hand, the curve (b) of FIG. 17
indicates only a noise component in the case where plasma is not
generated in the space 6 (304). However, since they are many cases
where plasma generated inside the space 6 (304) is unstable, it is
not always possible to obtain the current voltage characteristic
having good symmetry as shown in FIG. 17. Therefore, in a case
where the current value is observed to exceed 10.sup.-7A, even only
slightly, it is generally judged that plasma has been generated in
the space 6 (304).
[0408] In this embodiment, plasma ignition tests were carried out
for 6 different conditions by combining the cases where the
distance tg between the two glass plates (301 and 302) was 0.7 mm
and 4 mm, and where the microwave frequency was 2,45 GHz, 5.0 GHz
and 8.3 GHz. At this time, Ar gas was introduced so that the
pressure inside the space 6 (304) was 0.1-10 Torr. Also, the
microwave power was supplied up to a maximum of 1600W.
[0409] Table 1 shows the results of the plasma ignition tests for
the above described 6 conditions. In the table, the mark O
indicates that plasma was not generated inside the space 6 (304)
and the mark x indicates that plasma was generated inside the space
6 (304).
1 TABLE 1 Microwave frequency [GHz] Tg [mm] 2.45 5.0 8.3 0.7 X
.largecircle. .largecircle. 1.4 X X X
[0410] As shown in table 1, in the set of cases where the distance
between the two glass plates (301 and 302) [namely the width of the
space 6 (304)] tg is 0.7 mm and the microwave frequency is 5.0 GHz
or 8.3 GHz, even if microwave power was delivered up to 1600W
(power density 1.27W/cm.sup.2) there was no plasma excitation
inside the space 6 (304). On the other hand, in the other cases it
was confirmed that there was plasma excitation.
[0411] FIG. 18 shows results of studying the relationship between
minimum discharge power and Ar pressure for the four conditions
where plasma is not generated, among the six conditions described
above. From FIG. 18, it will be understood that in the case where
the microwave frequency is low (for example 2.45 GHz), even if the
width tg of the space 6 (304) is narrowed down to 0.7 mm, plasma
excitation occurs inside the space 6 (304) at low power.
[0412] Contrary to this, by making the microwave frequency high
(for example 5.0 GHz), and narrowing the width tg of the space 6
(304) to 0.7 mm or less, even if microwave power is delivered up to
1600W (power density 1.27W/cm.sup.2) plasma is not excited inside
the space 6 (304).
[0413] Accordingly, in the plasma device shown in FIG. 15, in order
to stop plasma excitation in the space 1 (208) between the first
dielectric plate 102 and the second dielectric plate 116, microwave
frequency input to the antenna is made at least 5.0 GHz, and the
width of the space 1 (208) is made 0.7 mm or less.
[0414] Also, in the plasma device shown in FIG. 15, when a pressure
1 (P1) of the space 1 (208) between the first dielectric plate 102
and the second dielectric plate 116, and a pressure 2 (P2) of space
2 (209) surrounded by the second dielectric plate 116 and wall
sections (chamber) 101 of the container other than the second
dielectric plate 116, and where an electrode 109 for holding the
object to be treated 104 is arranged, have the relationship
P1>P2, it was confirmed that plasma excitation did not occur in
the space 1 (208). Particularly, it is understood that when P1 is
sufficiently high compared to P2, for example when there was a
pressure difference of about 10 times, these effects were more
remarkable.
[0415] Accordingly, by providing means 5 for generating a pressure
difference so that the pressure 1 (P1) of the space 1 becomes
higher than the pressure 2 (P2) of the space 2 (209) it is possible
to prevent plasma excitation in the space 1 (208).
[0416] (Embodiment 8)
[0417] With this embodiment, in the plasma device shown in FIG. 15,
the effects were studied of either reducing in size, shielding, or
not providing at all, those slots, among slots (hole portions
penetrating the slot plate) provided in the slot plate constituting
the antenna, arranged at sections where the density of plasma
generated in the space 2 (209) is locally high.
[0418] FIG. 19 is a schematic cross sectional drawing showing the
slot plate when a shielding plate 119 is provided on the slots 110'
positioned close to the center of the slot plate. FIG. 20 is a
schematic plan view showing the slot plate when the size of the
slots 110' positioned close to the center of the slot plate is
reduced. FIG. 20(b) is an enlarged view of region A of FIG.
20(a).
[0419] In FIG. 20, the case is shown where the length is shortened
for only two rings of slots from the center of the slot plate, but
reduction in size of the lots can be realized by, for example,
shortening the slot length.
[0420] FIG. 21 shows results of studying the density of plasma
generated at the space 2 (209), using the slot plate shown in FIG.
19. In FIG. 21, slot A, slot B and slot C are the names
respectively given to the slot distributions for the case when the
shielding region is small, the case where the shielding region is
intermediate in size, and the case where the shielding region is
large. From FIG. 21 it will be understood that with slot A, the
density of plasma at the center of a measuring electrode is raised.
By arranging the shielding plate 119 at this portion so that slot
distribution is slot B, it can be expected to make the plasma
density uniform. However, if the shielding region is made wider, as
in slot C, conversely to slot A the plasma density rises at the
outer edge of the electrode.
[0421] Accordingly, by providing a shielding plate 119 having an
appropriate shielding region, the output of electromagnetic waves
radiated from the slots is reduced, and the density of excited
plasma can be made even more uniform.
[0422] A shielding plate 119 that can hope to achieve the above
describe operation and effect preferably has a shape and size so as
to shield the slots of the slot plate. Namely, it goes without
saying that either by reducing the slot size or even using a method
of not providing any slots, the same effects can be anticipated as
in the case where the slots are shielded.
[0423] (Embodiment 9)
[0424] With this embodiment, in the plasma device shown in FIG. 15,
the effects were studied of providing means 6 for maintaining the
antenna at a fixed temperature close to the antenna, and means 7
for maintaining the temperature of the first dielectric plate at a
fixed temperature close to the first dielectric plate.
[0425] In the plasma device shown in FIG. 15, as shown in FIG. 22,
structures 120 and 121 capable of maintaining the antenna guide
108, waveguide dielectric plate 103, antenna slot plate 106, and
first dielectric plate 102 at a fixed temperature are provided
close to the antenna guide 108. The structures 120 and 121 are
equivalent to the means 6 and the means 7.
[0426] In this case, the antenna slot plate 106 is arranged so as
to be completely stuck to the waveguide dielectric plate 103. By
having this arrangement, if a gap exists between the antenna slot
plate 106 and the waveguide dielectric plate 103, surface waves
will be generated at that part, and it is possible to effectively
avoid a phenomenon where it is impossible to radiate
electromagnetic waves. To do this, the shape of the waveguide
dielectric plate 103 must hardly be changed by forces or heat from
outside, and it is necessary to use a material having high thermal
conductivity and low microwave loss, for example, quartz glass
(SiO.sub.2), aluminium nitride (AlN) etc., but it is not limited to
these materials, and any material can be used as long as it
satisfies the above described conditions.
[0427] In this embodiment, in the two structures 120 and 121, a
method is employed where heating medium flows and desired locations
are cooled, but a material having high thermal conductivity is
preferred as the heating medium. As such a heating medium, fluid,
gas (helium, nitrogen, etc.) and the like can be considered, but
they are not limiting.
[0428] (Embodiment 10)
[0429] As shown in FIG. 23, this embodiment is different from
embodiment 9 in that a spacer 118 is provided in a space between
the antenna slot plate 106 and the first dielectric plate 102 as
means for preventing warping of the slot plate. In this embodiment
the spacer 118 is made of TEFLON.
[0430] In the case where it is impossible prevent warping of the
slot plate in embodiment 9, by providing the spacer 118 in a space
between the antenna slot plate 106 and the first dielectric plate
102 it becomes possible to prevent warping of the antenna slot
plate 106.
[0431] The spacer 118 is provided at a position where the slots 119
of the slot plate 106 do not open out so as not to impede radiation
of electromagnetic waves from the slot plate 106.
[0432] (Embodiment 11)
[0433] As shown in FIG. 24, this embodiment differs from embodiment
9 in that a sensor 122 is provided either in the container or at
the edge of the container, as means 9 for detecting the presence or
absence of generated plasma in the space 2.
[0434] The sensor 122 is connected to a microwave power supply, not
shown in the drawing, and when plasma is being excited in the
chamber 101 it detects plasma, causes the microwave power supply to
provide output and plasma excitation is inhibited, while when
plasma is disappearing the sensor 122 immediately suspends output
from the microwave power supply. In this embodiment, a photo
transistor is used as the sensor 122, and detects plasma light
emission, but it is perfectly acceptable to use alternate
means.
[0435] Accordingly, by adopting the sensor 122 it is possible to
prevent careless heating and damage of the inside of the chamber
101 and the object to be treated 104 etc due to magnetic waves
radiated from the antenna 201 when plasma activation suddenly
stops.
[0436] (Embodiment 12)
[0437] In this embodiment, the effects of having a structure for
causing the temperature of the container wall surface and parts
other than the object to be treated inside the container to be
raised to 150.degree. C., and/or a structure for causing the
temperature inside all the units constituting the exhaust system to
be raised to 150.degree. C.
[0438] The above described effects were studying a relationship
between container inner wall temperature and reaction by-product
(polymerization film) deposition, namely, dependence of deposited
film thickness on inner wall temperature using the vacuum device
shown in FIG. 25 in a range of 50-150.degree. C.
[0439] In FIG. 25, reference numeral 501 is a chamber, reference
numeral 502 is plasma, reference numeral 503 is an object to be
treated, reference numeral 504 is an electrode, reference numeral
505 is a heater, reference numeral 506 is a laser, and reference
numeral 507 is a photodetector. In this case, gas used was a
mixture of C.sub.4F.sub.8 and H.sub.2O, [C.sub.4F.sub.8:H.sub.2O
7:3, total gas flow amount:40 (sccm)], pressure was 10 mTorr, and
discharge power was 1000W. With the vacuum device of FIG. 25, an Si
wafer was used attached to a flat tip of a copper rod, as the
object to be treated 503, and heating of the object to be treated
was carried out using a sheath heater provided inside the rod.
[0440] FIG. 26 shows the results of studying the relationship
between the deposition rate of the polymerization film and the
temperature of the inner wall of the chamber. From FIG. 26 it will
be understood that the polymerization film deposition rate is
rapidly decreased accompanying increase in wafer temperature and
that at around 150.degree. C. deposition of the polymerization film
could not be observed.
[0441] Accordingly, it was determined that by providing either a
structure for causing the temperature of the container wall surface
and parts other than the object to be treated inside the container
to be raised to 150.degree. C., and/or a structure for causing the
temperature inside all the units constituting the exhaust system to
be raised to 150.degree. C., it was possible to prevent the build
up of a polymerization film composed of moisture and reaction
by-products.
[0442] (Embodiment 13)
[0443] As shown in FIG. 27, this embodiment differs from embodiment
9 in that a Xenon (Xe) lamp is used as means for heating the object
to be treated 104.
[0444] The Xe lamp 125 can effectively heat only the surface of the
object to be treated 104 by irradiating light to the object to be
treated 104 through a light inlet 124 and a window 123 made of a
material that passes light.
[0445] In this embodiment a Xe lamp is used as means for heating
the object to be treated 104, but another light source can be used,
or the electrode 109 holding the object to be treated 104 can be
heated by a direct electrothermal line etc., but heating using Xe
lamp irradiation is preferred.
[0446] Also, in FIG. 27 the Xenon lamp inlet 124 is provided on
part of the outside of the chamber 101, but it is more preferable
to uniformly provide a plurality of such inlets on the outside of
the chamber 101.
[0447] (Embodiment 14)
[0448] A simple schematic drawing of the situation when adopting a
staged cooler method in the collection and recycling of
fluorocarbon gas is shown in FIG. 28. It is possible to carry out
recycling of the gas expelled from inside the container as a liquid
by gradually cooling from a high boiling point gas and performing
liquefaction and distillation purification. Fluorocarbon gas
contributes to global warming 100,000 1,000,000 times more than
CO.sub.2, which means that the effects of collecting and recycling
the fluorocarbon gas is immense.
[0449] (Embodiment 15)
[0450] A self cleaning gas plasma has to satisfy the following two
requirements in order to rapidly remove reaction gas products
adhered to the chamber without inflicting damage on the inner wall
of the chamber.
[0451] {circle over (1)} high ion density and radical density
[0452] {circle over (2)} low plasma potential (small energy of ions
incident to the chamber wall)
[0453] Also, at the same time as these two requirements, there is
also a demand for material of the inside of the chamber to have
strong ion radiation and extremely good plasma resistance.
[0454] FIG. 29 shows the relationship between average binding
energies of various fluorine type gases and their plasma parameter.
From this drawing, it will be more clearly understood that there is
an intimate relationship between binding energy and plasma
parameter. Namely, ion irradiation energy becomes small and ion
density becomes high as binding energy falls. Plasma energy does
not depend largely on binding energy of gas molecules. From this it
will be understood that NF.sub.3 is an extremely suitable gas for
self cleaning. Accordingly, when a self cleaning structure is
required the inner walls of the container must have excellent
plasma resistance and it is best to use an alloy such as
AlF.sub.3/MgF.sub.2.
[0455] FIG. 30 shows the results of evaluating damage caused by
plasma irradiation of AlF.sub.3/MgF.sub.2 alloy when is used as the
chamber inner wall material of the device of FIG. 15, and gas
having a small gas molecule binding energy (such as NF.sub.3) is
used as cleaning gas. FIG. 30(a) is a profile of the
AlF.sub.3/MgF.sub.2 alloy in a depth direction using XPS (X ray
photoelectron spectroscopy) before NF.sub.3 plasma irradiation, and
FIG. 30(b) is a profile after two hours of NF.sub.3 plasma
irradiation. From the results shown in FIG. 30, it will be
understood that there is hardly any damage attributable to plasma
irradiation.
[0456] Accordingly, when there is a need to have a self cleaning
structure in the device the container inner walls must have
excellent plasma resistance and it is best to use
AlF.sub.3/MgF.sub.2 alloy.
[0457] (Embodiment 16)
[0458] With this embodiment, in the plasma device of FIG. 15 an
antenna 201 is located outside the container 101 via the first
dielectric plate 102, and plasma excitation is caused by
introducing microwaves through a coaxial tube 107 and radiating
electromagnetic waves inside the container 101.
[0459] FIG. 31 is a graph showing the results of measuring
distribution of ion saturation current, FIG. 32 is a graph showing
the results of measuring distribution of electron temperature, and
FIG. 33 is a graph showing the results of measuring distribution of
electron density.
[0460] From FIG. 31 to FIG. 33 it will be understood that with the
plasma device of the present invention, uniform plasma excitation
can be caused by covering high density plasma having a ion
saturation current of at least 14 mA/cm.sup.2, electron density in
the region of 1.eV (15000K) and electron density of at least 1012
over a large surface area of diameter 300 mm or more inside the
container 101.
[0461] FIG. 34 is a schematic drawing of a system for measuring the
ion current distribution. This is measurement of ion current
distribution using a disk-shaped electrode 401. The disk-shaped
electrode 401 was used in place of the object to be treated 104 and
electrode 109 in the plasma device shown in FIG. 15.
[0462] In FIG. 34, reference numeral 401 is the disk-shaped plate,
reference numeral 402 is a pin reference numeral 403 is an
aluminium wire, reference numeral 404 is a resistor, reference
numeral 405 is an operational amplifier, reference numeral 406 is
an A-D converter, reference numeral 407 is a computer, reference
numeral 408 is a stepping motor and reference numeral is a power
supply.
[0463] The disk-shaped electrode 401 in FIG. 34 is a piece of
disk-shaped aluminum having a diameter of 300 mm .phi. and nine
pins 402 are embedded in the top of the disk-shaped electrode 401
an equal distance apart on a line running from the center to a
point at a radius of 140 mm.
[0464] Electric current flowing from the plasma to the pins 402 is
taken outside the chamber through ceramics-coated aluminium wires
403 connected to the pins 402 and current introduction terminals
(not shown). A voltage of -20V relative to the potential of the
chamber is applied to the pins 402, and only positive ions flow in
the plasma. A potential generated by this positive ion flow is
converted to a voltage signal by the resistor 404, and after being
amplified by the operational amplifier 405 is converted to a
digital signal by the 16 channel A-D converter 406 and transmitted
to the computer 407.
[0465] The aluminium electrode 401 is covered with polyimide tape
(not shown). Measurements of rotation of the electrode 401 by the
stepping motor 408, and measurements of ion current by the A-D
converter are synchronized using the computer 407. Measurement of
ion current is carried out 200 times for each pin 402 per rotation
of the electrode 401, to obtain a fine two dimensional
distribution.
[0466] FIG. 35 is a schematic diagram showing a single probe system
used in measurement of electron temperature and electron density in
this example.
[0467] If the probe is inserted into a section where the microwave
power density is large, as shown in FIG. 35, the probe tip
(tungsten wire, 0.1 mm .phi.) 601 is heated by the microwaves, and
there is a possibility that thermoelectrons will be discharged.
There is also a possibility that ionization will occur frequently
inside the probe seal. In either case it becomes impossible to
obtain a voltage current characteristic of an ordinary single
probe.
[0468] Therefore, 0.5 mm diameter silver wire 602 wound in a spiral
manner is arranged clearing a gap at the edge of the probe tip 601
for the purpose of shielding microwaves. The silver wire has low
resistance and is not heated by the. Also, the use of comparatively
fine wire for shielding is so that the effect on the plasma can be
kept to a minimum.
[0469] A comparison was carried out for the case where the silver
wire was provided in a spiral manner, and the case where it was
not. At a section where the microwave power density was small,
hardly any difference could be seen between the two
characteristics. At a section where the microwave power density was
large, in the case where the silver wire was not arranged in a
spiral manner, when a negative potential was applied to the probe
the current value was noticeably increased, but in the case where
the silver wire was arranged in a spiral manner a normal
characteristic was obtained. In this way, in the case where
microwave power density inside the plasma is large, it is effective
to shield the edge of the probe tip 601 from microwaves using a
metallic wire etc.
[0470] In order to obtain a z direction [in the device of FIG. 15 a
direction from the second dielectric plate 116 facing the electrode
401] distribution for each plasma parameter, a structure was made
that could move the probe in the z direction using the stepping
motor 408. The maximum speed of movement of the probe was 300
mm/sec and the positional resolution was 0.02 mm. control of probe
position using the stepping motor 408 and measurement of the
current voltage characteristic was synchronized using the computer
497. In order to prevent heating of the probe, experimentation was
carried out restricting the time of reciprocation in the z
direction to less than 5 seconds.
[0471] (Embodiment 17)
[0472] With this embodiment, plasma etching was carried out for the
object to be treated 104 by applying a high frequency to the
electrode 109 having the function of holding the object to be
treated 104, in the plasma device shown in FIG. 15. An Si wafer
formed in the surface of a Poly-Si film mainly used as a gate
electrode material for a MOS transistor was used as the object to
be treated 104, and this Poly-Si film was etched.
[0473] A high frequency was applied to the electrode 109 having the
function of holding the object to be treated 104 from means (not
shown) capable of applying a high frequency bias. Gas such as
Cl.sub.2, O.sub.2, HBr etc was used as the source material gas, but
this is not limiting. FIG. 36 is a graph showing results of the
plasma etching. From FIG. 36, for a total of nine measurement
points (the center point and 8 points spaced equally apart in two
rings of four 150 mm and 280 mm from the center) on the object to
be processed (size 300 mm .phi.), with an etching rate uniformity
of the Poly-Si film of about 5% per unit time, it was confirmed
that extremely uniform etching was possible on a large diameter
(300 mm.phi.) object to be treated.
[0474] (Embodiment 18)
[0475] In this embodiment the case where the device of the present
invention is applied to a plasma oxidation device for oxidizing the
surface of an object to be treated at low temperature is
illustrated. Here, description will be given for the case where an
Si substrate was used as the object to be processed, the and a gate
oxidation film was formed on the surface of the object to be
treated using direct oxidation with O.sub.2.
[0476] Ar and O.sub.2 were used as source material gases. It is
also possible to use Xe in place of Ar as a carrier gas. It is also
possible to add He etc. to a mixed gas comprising Ar and
O.sub.2.
[0477] FIG. 37 is a schematic diagram showing a combination of a
cross section of elements constituting this example, and a system
for measurement of element withstand voltage.
[0478] In FIG. 37, the element whose withstand voltage has been
measured comprises an object to be treated 701 constituted by an n
type Si wafer, a field oxidation film 702, a gate oxidation film
703, and a gate electrode 704. Also, reference numeral 705 is a
probe used in measurement of withstand voltage, reference numeral
706 is a voltmeter, reference numeral 707 is voltage applying means
and reference numeral 708 is an ammeter.
[0479] Formation of the element shown in FIG. 37 and measurement of
the withstand voltage are carried in the following order.
[0480] (1) After a field oxidation film 702 (thickness:800 nm)
formed of SiO.sub.2 has been formed on the n type Si wafer using a
thermo oxidation method [(H.sub.2+O.sub.2 gas), H.sub.2=1 l/min,
O.sub.2=1 l/min, temperature of object to be treated=1000.degree.
C.], part of the field oxidation film 702 was subject to etching
processing and the surface of the n type Si wafer was exposed.
[0481] (2) Only the exposed surface of the field oxidation film 702
was directly oxidized using the plasma device of the present
invention, and the SiO.sub.2 gate oxidation film 703 (surface area
1.0.times.10.sup.-4 cm.sup.2, thickness 7.6 nm) was formed.
[0482] The film forming conditions at this time were film forming
gas (Ar+O.sub.2), gas pressure 30 mTorr, partial pressure ratio
Ar:O.sub.2=98:2, microwave power 700W, oxidation processing time 20
min, the object to be treated was held in an electrically floating
state, and the temperature of the object to be treated was
430.degree. C.
[0483] (3) A gate electrode 704 of Al (thickness 1000 nm) was
formed on the field oxidation film 702 and the gate oxidation film
703 by a vapor deposition method.
[0484] (4) The probe 705 was brought into contact with the gate
electrode 704, a d.c voltage was applied to the object to be
treated 701 formed of the n type Si wafer via the gate electrode
704, and the voltage at which the gate oxidation film 703 suffered
dielectric breakdown (namely the withstand voltage) was measured
using the voltmeter 706.
[0485] FIG. 38 is a graph showing the results of measuring
withstand voltage. FIG. 38(a) shows the case when the gate
oxidation film is manufactured using the device of the present
invention. On the other hand, FIG. 38(b) shows the case when the
gate oxidation film is manufactured using a device of the related
art. With a conventional device, plasma is generated by applying a
high frequency of 100 MHz to parallel plate type electrodes, and
the gate oxidation film is formed.
[0486] In FIG. 38, the horizontal axes represent withstand voltage
and the vertical axes represent the frequency with which elements
were obtained for each withstand voltage. For example, the bar
graph at the 10MV/cm part of the horizontal axis is the frequency
of occurrence of elements having withstand voltage in the range
9.5-10.4MV/cm. The number of elements measured was 30 for each of
FIG. 38(a) and FIG. 38(b).
[0487] The following points become clear from FIG. 38.
[0488] {circle over (1)} Elements manufactured using the device of
the related art have a wide withstand voltage distribution (that
is, uniformity is bad) and average withstand voltage is 10.2MV/cm
[FIG. 38(b)].
[0489] {circle over (2)} Elements manufactured using the device of
the present invention have a narrow withstand voltage distribution
(that is, uniformity is good) and a high average withstand voltage
of 11.9MV/cm can be obtained, so it is understood that the film
quality of the gate oxidation film has been improved [FIG.
38(a)].
[0490] Accordingly, by carrying out direct oxidation using the
plasma device provided with the radial line slot antenna of the
present invention, it is possible to form an oxidation film having
high uniformity and high withstand voltage, which means that it was
confirmed that elements having excellent withstand voltage could be
manufactured stably.
[0491] In this example, the device of the present invention has
been applied to a plasma oxidation device for oxidizing the surface
of an object to be treated at a low temperature, but it was also
confirmed that it was possible to obtain high uniformity oxidation
films by applying it to a plasma nitriding device for nitriding the
surface of an object to be treated.
[0492] (Embodiment 19)
[0493] This example shows an embodiment for the case where the
present invention is applied to a plasma CVD device for film
formation of a thin film on the surface of a substrate. Description
will be given for the case where single crystalline Si is formed as
a film on an amorphous Si substrate.
[0494] In the example, film formation of single crystalline Si is
carried out on an amorphous Si substrate, but it is also possible
to form polycrystalline Si as a thin film on amorphous Si. The
material of the substrate on which film formation is carried out is
not limited to Si and can be a glass or quartz substrate, etc.
[0495] SiH.sub.4, H.sub.2, and Ar are used as the source material
gas, but the source material gas is not limited to this combination
and it is possible to use Xe in place of Ar, although Xe is
preferred.
[0496] The proportion of Ar must be maintained at at least half of
the total amount. In this example, Ar is provided in a proportion
of 50%, but this is not limiting. The reason for this is that on a
plasma excitation method using microwaves, since it is necessary to
have a quite high electron density within the plasma in order to
maintain excitation of the plasma, it is necessary to increase the
proportion of Ar that can obtain a higher electron density.
[0497] Also, the amorphous Si substrate surface is heated up to a
temperature of 500.degree. C. by irradiation by a xenon lamp and an
insufficient energy is compensated for by plasma ion irradiation.
It is also possible to use other temperature raising methods, but
the method using a xenon lamp is preferred.
[0498] In order to form a film of single crystalline Si on the
amorphous Si substrate, it is necessary for the kernel of crystal
Si grown on the substrate surface during film formation to have the
same in-plane orientation as the substrate. This means that if
differences exist in the film in-plane formation conditions, film
formation will be carried out with unequal orientation of the
crystal kernel, so there is a necessity to make in-plane film
formation conditions exactly uniform.
[0499] By using the plasma device of the present invention, it is
possible to provide uniform film formation conditions over a large
surface area, and for the first time it becomes possible to form a
film of single crystalline Si on an amorphous substrate at low
temperature, which was impossible in the related art.
[0500] As a result, it was possible to form a single crystalline Si
film on a Si substrate of 300 mm in diameter at a temperature of
500.degree. C. and a film formation rate of 0.1 .mu.m every
minute.
[0501] Results of forming a film of Poly-Si on a glass substrate
also show that it is possible to obtain a high quality thin film
with a mobility (carrier transfer rate) of 300 or greater.
[0502] (Embodiment 20)
[0503] This example is different from embodiment 19 in that a film
of SiO.sub.2 is formed on the Si substrate, and the remaining
aspects are the same and will be omitted.
[0504] In this example, SiH.sub.4, O.sub.2 and Ar are used as the
source material gas, but this combination of gases is not limiting
and it is possible to use Xe in place of Sr as a carrier gas, and
N.sub.2O can be used instead of O.sub.2. It is also possible to add
He etc, to the mixed gas comprising SiH.sub.4, O.sub.2 and Ar.
[0505] As a result, it was possible to form a film on an Si
substrate of 300 mm in diameter at a temperature of 350.degree. C.
and a film formation rate of 0.1 .mu.m every minute and in-plane
uniformity was less than .+-.5%.
[0506] (Embodiment 21)
[0507] This example is different from embodiment 19 in that a film
of Si.sub.3N.sub.4 is formed on the Si substrate, and the remaining
aspects are the same and will be omitted.
[0508] In this example, SiH.sub.4 and NH.sub.3 are used as the
source material gas, but this combination of gases is not limiting
and it is possible to use Xe in place of Ar, and N.sub.2 can be
used instead of NH.sub.3.
[0509] As a result, it was possible to form a film on a Si
substrate of 300 mm in diameter uniformly at room temperature and
with a film formation rate of 0.1 .mu.m every minute, and in-plane
uniformity was less than .+-.5%.
[0510] (Embodiment 22)
[0511] This example is different from embodiment 19 in that a BST
thin film [(Ba, Sr) TiO.sub.3], being a ferroelectric thin film, is
formed on a Pt thin film that has been formed on the Si substrate.
The remaining aspects are the same as embodiment 19 and will be
omitted.
[0512] In this example, Ba(DPM).sub.2, Se(DPM).sub.2, and
TiO(O-iC.sub.3H.sub.7).sub.2 and Ar are used as the source material
gas, but this combination of gases is not limiting and it is
possible to use Xe in place of Sr, although it is preferable to use
Xe rather than Ar.
[0513] The Pt thin film is formed on the Si substrate beforehand
using a sputtering method, and also serves as barrier metal to
prevent the electrode and the Si substrate against reaction with a
foundation of Ba, Sr, Ti. This embodiment is not limited to the Pt
thin film, and it is also possible to use Ru or RuO.sub.2 etc.
[0514] As a result, it was possible to achieve a film formation
rate of 0.5 mm every minute uniformly on a Si substrate of 300 mm
in diameter at a temperature of 450.degree. C., and the relative
permittivity of the thin film was approximately 160.
[0515] (Embodiment 23)
[0516] This example is different from embodiment 19 in that a SBT
thin film [SrBi.sub.2Ta.sub.2O.sub.9] is formed on a Pt thin film
that has been formed on the Si substrate. The remaining aspects are
the same as embodiment and will be omitted.
[0517] In this example, Sr(DPM).sub.2, Bi(C.sub.6H.sub.5).sub.3,
TiO(O-iC.sub.3H.sub.7).sub.2 and Ar are used as the source material
gas, but this combination of gases is not limiting and it is
possible to use Xe in place of Sr, although it is preferable to use
Xe rather than Ar.
[0518] As a result, a ferroelectric thin film having a remanence of
about 30 .mu.m/cm.sup.2 was obtained.
[0519] (Embodiment 24)
[0520] This example shows the case where the present invention is
applied to a plasma CVD device for formation of a diamond thin film
on the surface of a substrate. Description will be given for the
case where Si is used as a substrate and film formation is carried
out on this substrate.
[0521] In this example CO, H.sub.2, O.sub.2 and Ar are used as the
source material gas, but this combination is not limiting.
[0522] The substrate temperature was set to 500.degree. C. Also,
the diamond thin film was formed by simultaneously proceeding with
the elementary reactions of decomposition and deposition of carbon
gas, diamond nucleation, generation of sp.sup.3 carbon, and removal
of by-products (graphite type carbon, polymer). In the formation of
the diamond thin film, ion energy must be low, and compared to a
plasma device of the related art the device of the present
invention enables plasma generation over a large surface area at
high density and low energy, which means that film formation rate
can be increased and high quality thin film formation is
possible.
[0523] (Embodiment 25)
[0524] This example is different from embodiment 19 in that a
P--SiN film is formed on the Si substrate, and the remaining
aspects are the same as embodiment 19 and will be omitted.
[0525] In this example, the substrate temperature was 300.degree.
C. and SiH.sub.4, NH.sub.3 and Ar were used as the source material
gas, but this combination of gases is not limiting and it is
possible to use Xe in place of Sr, and to replace NH.sub.3 with
N.sub.2.
[0526] As a result, it was possible to form a film on a Si
substrate of 300 mm in diameter at a film formation rate of 0.1
.mu.m every minute and in-plane uniformity was less than
.+-.5%.
[0527] (Embodiment 26)
[0528] This example is different from embodiment 19 in that a
P--SiO film is formed on the Si substrate, and the remaining
aspects are the same as embodiment and will be omitted.
[0529] In this example, the substrate temperature was 300.degree.
C. and SiH.sub.4, N.sub.2O and Ar were used as the source material
gas, but this combination of gases is not limiting and it is
possible to use Xe in place of Sr.
[0530] As a result, it was possible to form a film on a Si
substrate of 300 mm in diameter at a film formation rate of 0.1
.mu.m every minute and in-plane uniformity was less than
.+-.5%.
[0531] (Embodiment 27)
[0532] This example is different from embodiment 19 in that a BPSG
film is formed on the Si substrate, and the remaining aspects are
the same as embodiment 19 and will be omitted.
[0533] In this example, the substrate temperature was 450.degree.
C. and SiH.sub.4, PH.sub.3, B.sub.2H.sub.6, O.sub.2 and Ar were
used as the source material gas, but this combination of gases is
not limiting and it is possible to use Xe in place of Sr.
[0534] As a result, it was possible to form a film on a Si
substrate of 300 mm in diameter at a film formation rate of 0.1
.mu.m every minute and in-plane uniformity was less than
.+-.5%.
[0535] (Embodiment 28)
[0536] This example shows the case where the device of the present
invention is applied to a plasma nitriding device for nitriding the
surface of an object to be treated at low temperature. Description
will be given for the case where an Si substrate is used as the
object to be treated and direct nitriding is carried out on the
surface of the Si substrate using N.sub.2. The source material gas
was Ar and N.sub.2. It is also permissible to use He or Xe in place
of Ar as a carrier gas. Also, He, Ne, Xe etc. can be added to the
mixed gas comprising Ar and N.sub.2. It is also possible to replace
N.sub.2 with NH.sub.3.
[0537] FIG. 39 is a graph showing results of analyzing the chemical
binding state of a Si surface, using an X-ray photoelectron
spectroscope, after direct nitriding of the Si substrate surface
for 30 minutes using a mixed gas of Ar/N.sub.2=97%/3% and growth of
a 5 nm nitride film, using the device of the present invention. The
horizontal axis represents binding energy between photoelectrons
and a nucleus, and the vertical axis represents the number of
electrons having that binding energy. For the sake of comparison,
the spectrum of the surface of 5 nm silicon nitride film grown by
processing in an N.sub.2 atmosphere at 1300.degree. C. for 120
minutes is also shown.
[0538] From FIG. 39 a peak attributable to the silicon substrate
and a peak of the silicon nitride film grown on the substrate were
confirmed in the spectrum for the silicon nitride film grown using
the device of the present invention. From the fact that the
position and shape of the peak attributable to the silicon
substrate were almost the same as those for the silicon nitride
film formed at 1300.degree. C., it was confirmed that the formed
silicon nitride film was complete.
[0539] FIG. 40 is a schematic drawing showing a combination of a
cross section of an element formed in the present embodiment and a
system for measuring dielectric breakdown injection charge amount
for the element. In FIG. 40, the element that has had dielectric
breakdown injection charge amount measured comprises an object to
be treated 801 made of an n type Si wafer, a field oxidation film
802, a gate nitride film 803 and a gate electrode 804. Also,
reference numeral 805 is a probe used in measurement of dielectric
breakdown injection charge amount, reference numeral 806 is a
voltmeter, reference numeral 807 is a constant current source and
reference numeral 808 is an ammeter.
[0540] Element formation and dielectric breakdown injection charge
amount measurement shown in FIG. 41 are carried out using the
measurement meter shown in FIG. 40 and carrying out the following
procedure.
[0541] (1) After a field oxidation film 802 (thickness:800 nm)
formed of SiO.sub.2 has been formed on the n type Si wafer 801
using a thermo oxidation method [(H.sub.2+O.sub.2 gas), H.sub.2=1
l/min, O.sub.2=1 l/min, temperature of object to be
treated=1000.degree. C.], part of the field oxidation film 802 was
subject to etching processing and the surface of the n type Si
wafer was exposed.
[0542] (2) Only the exposed surface of the field oxidation film 802
was direct nitrided using the plasma device of the present
invention, and the gate nitride film 803 (surface area
1.0.times.10.sup.-4 cm.sup.2, thickness 5.6 nm) formed of
Si.sub.3O.sub.4 was formed. The film forming conditions at this
time were film forming gas (Ar+N), gas pressure 30 mTorr, partial
pressure ratio Ar/N.sub.2=99.7%-90%/0.3%-10%, microwave power 700W,
nitriding processing time 30 min, the object to be treated was held
in an electrically floating state, and the temperature of the
object to be treated was 430.degree. C.
[0543] (3) A gate electrode 804 of Al (thickness 1000 nm) was
formed on the field oxidation film 802 and the gate nitride film
803 by a vapor deposition method.
[0544] (4) The probe 805 was brought into contact with the gate
electrode 804, a constant current was applied to the object to be
treated 801 formed of the n type Si wafer via the gate electrode
804 using the constant current source 807 so the electron density
became 200 mA/cm.sup.2, and time taken for the gate nitride film
803 to suffer dielectric breakdown was measured. The electron
density value multiplied by this time is the dielectric breakdown
injection charge amount.
[0545] FIG. 41 is a graph showing results of measuring the
dielectric breakdown injection charge amount of a silicon nitride
film formed at 430.degree. C. using the device of the present
invention. For the sake of comparison, the dielectric breakdown
injection charge amount for a silicon nitride film formed at
1300.degree. C. in an N.sub.2 atmosphere is also shown. In FIG. 41
the horizontal axis represents injection charge amount and the
vertical axis represents the cumulative frequency of elements
obtaining each of the charge injection amounts. Twenty elements
were measured. From FIG. 41 it is understood that in the case of
forming a nitride film on an Si substrate using the device of the
present invention, even at a film formation temperature as low as
there was no effect (With normal film formation at 430.degree. C.
it is impossible to even cause direct nitriding on the surface of a
silicon substrate. In order to carry out nitriding of a silicon
surface using N.sub.2 gas a substrate of at least 1000.degree. C.
is required.), a maximum dielectric breakdown injection charge
amount of 123 C/cm.sub.2 was obtained, and the same characteristic
as that for dielectric breakdown injection charge amount for a film
formed at 1300.degree. C. was exhibited.
[0546] Accordingly, by carrying out direct nitriding of a silicon
surface using the device of the present invention, formation of a
silicon nitride film having the same electrical characteristic as a
silicon nitride film formed at 1300.degree. C. was achieved even at
a low temperature of 430.degree. C.
[0547] In this embodiment, the device of the present invention has
been applied to a plasma nitriding device for nitriding the silicon
surface of an object to be treated at low temperature, this
embodiment is not limited to Si and even if it was applied to
nitriding of metallic surfaces such as Ta, W, Al, Ti etc it was
confirmed that it was possible to obtain a high quality metallic
nitride film at a low substrate temperature.
[0548] (Embodiment 29)
[0549] This embodiment shows an example where the device of the
present invention is used as a plasma CVD device for forming a
polycrystalline silicon thin film on the surface of a substrate,
and formation of a polycrystalline silicon film on an oxidation
film that has been formed on the Si substrate. The source material
gas was a mixed gas of Ar and SiH.sub.4. It is also permissible to
add H.sub.2, He, Ne, Xe etc. to the mixed Ar and SiH.sub.4 gas. It
is also possible to use He or Xe in place of Ar. It is also
possible to use Si.sub.2H.sub.6, SiHCl.sub.3, SiH.sub.2Cl.sub.2 and
SiCl.sub.4 instead of SiH.sub.4 and obtain the same effects. An
oxidation film formed on the Si substrate to a thickness of 50 nm
using a thermal oxidation method [(H2+O2) gas, H2=1 l/min, O2=1
l/min, Si substrate temperature=1000.degree. C.] is used as the
substrate. In this embodiment, formation of the oxidation film is
carried out using a thermal oxidation method, but the means for
oxidation film formation is not thus limited and an oxidation film
formed by any means is permissible. After formation of the
oxidation film on the Si substrate, and after a polycrystalline
silicon thin film has been deposited to a thickness of 120 nm using
the device of the present invention under conditions of substrate
temperature 300.degree. C. and Ar/SiH.sub.4 99.95%/0.05%, the
polycrystalline silicon thin film is analyzed using an X-ray
diffractometer. For the sake of comparison, after a polycrystalline
silicon thin film has been deposited to a thickness of 120 nm using
a parallel plate type CVD device of the related art under
conditions of substrate temperature 300.degree. C. and
Ar/SiH.sub.4=99.95%/0.05%, the polycrystalline silicon thin film
was similarly analysed using an X-ray diffractometer.
[0550] FIG. 42 is a graph showing X-ray diffractometer measurement
results of the polycrystalline silicon thin films. The horizontal
axis represents an X-ray scattering angle 2.theta. attributable to
the surface direction, and the vertical axis represents the X-ray
strength at that scattering angle. A large peak strength of the
X-ray diffractometer indicates a high cystallinity in the surface
direction. From FIG. 42 it will be understood that the
polycrystalline silicon film formed using the device of the present
invention clearly has improved cystallinity compared to the film
formed using the parallel plate type CVD of the related art.
[0551] (Embodiment 30)
[0552] This embodiment shows the case where the present invention
is applied to a magnetron plasma etching device.
[0553] A plasma device has two plate type electrodes electrode I
and electrode II which are parallel to each other. A substrate to
be processed using plasma is mounted on a surface of electrode I
opposite to electrode II, and is provided with means for applying a
magnetic field being horizontal and unidirectional onto the
substrate. The electrode II comprises a central section
electrically connected to ground, and an outer section connected to
a high frequency power supply that can be controlled independently
of a high frequency power supply connected to the electrode I. A
focus ring is also provided at a section electrically connected to
electrode I, for the purpose of making the density of plasma
generated around the substrate surface uniform. The focusing ring
has means for adjusting junction impedance.
[0554] A structural drawing of the etching device of the present
invention is the same as FIG. 44 and so is omitted.
[0555] In this device, a dipole ring magnet (hereinafter referred
to as a DRM) having a plurality of permanent magnets lined up in an
annular shape is used as the magnetic field applying means. The
permanent magnets constituting the DRM are aligned so that
magnetization is performed in one direction as the magnet positions
go halfway round Here, a DRM is used as the magnetic field, but
other means for applying a magnetic field can also be used. Also,
the plasma density is increased here using a magnetic field, but
other means can also be used, and when there is no need to increase
plasma density there is no need to use any means at all.
[0556] The electrode II is a ring shaped metallic plate in this
case, and is provided in order to cause increased in-plane
uniformity of the plasma in the vicinity of the substrate surface.
High frequency power output from the high frequency power supply II
is applied to the electrode II via the matching circuit II. By
balancing electron drift on the surface of the electrode II, caused
by application of a magnetic field using application of a suitable
high frequency power to the electrode II, and electron drift on the
surface of the substrate, the plasma in the vicinity of the
substrate is made almost completely uniform. In a case where the
in-plane uniformity of the plasma is favourable even without the
application of a high frequency to the electrode II, or where there
is no problem even if it is not uniform, there is no need to
specially provide the electrode II. Similarly, also with respect to
the focus ring provided for the purpose of making the density of
the plasma to be generated in the vicinity of the substrate surface
uniform, in a case where the in-plane uniformity of the plasma is
favourable even without the application of high frequency to the
electrode II, or where there is no problem even if it is not
uniform, it is possible to either reduce the size of the focus ring
or not provide it at all.
[0557] As a material for the wall surface inside the container, a
material containing as low an amount of discharge gas (such as
moisture) as possible is used, in this case AIN. However, the
internal wall surface is not limited to this material. The high
frequency applied to the electrode I was 13.56 MHz, and the high
frequency applied to the electrode II was 100 MHz. In this case, by
making the frequency applied to the electrode II higher than the
frequency applied to the electrode I, a self bias voltage for the
electrode II becomes small which means that the problem of the
electrode II being sputtered by the plasma and the inside of the
container suffering from metallic contamination are solved. The
high frequencies applied to the electrodes I and II are not limited
to those in this example.
[0558] Only the exhaust system of the above described device was
modified and the major difference of the exhaust system of the
present invention was evaluated in comparison to the exhaust system
of the related art (i.e., the method disclosed in FIG. 43(a)). The
evaluation method was to prepare an insulation film BPSG to a
thickness of 1.51 .mu.m on an Si wafer 200 mm in diameter as the
substrate to be plasma processed, mount the substrate on electrode
I and carry out etching while increasing a total gas flow amount
with a fixed process gas ratio, and measuring the etching rate
using disparity between the exhaust systems. The conditions for
etching the substrate were power of a high frequency (13.56 MHz)
applied to the electrode I 1700W, power of a high frequency (100
MHz) applied to the electrode II 400W, process pressure 40 mTorr,
electrode spacing 10 mm, and process gas ratio of
C.sub.4F.sub.8:5%, CO:15%, Ar 78%, and O.sub.2:2%, but these
conditions are not limiting. The results of the evaluation are
shown in FIG. 57. (The marks .tangle-solidup.and .DELTA.represent
etching rate at the center of the wafer, while the marks
.box-solid. and .quadrature. represent etching rate at the end of
the wafer.) From these results the following point becomes
clear.
[0559] (1) In the case of adopting the exhaust system of the
present invention, it is understood that it is possible to obtain a
higher etching rate and uniformity than with the exhaust system of
the related art.
[0560] Also, BPSG is formed on a Si wafer of 200 nm in diameter to
a thickness of 1.5 .mu.m as the substrate, 0.7 .mu.m of mask
material referred to as resist was coated on this substrate, and
after carrying out exposure and developing processing a hole
pattern of diameter 0.18 .mu.m was formed on the mask material.
This substrate was etched under the same conditions as the above
described experiment, and after etching hole formation was
observed. As a result, the following point becomes clear.
[0561] (2) Reaction by-products clogging up the holes are
effectively expelled due to improved exhaust rate and increased
process gas flow amount, which makes it possible to obtain
favourable hole formation. Compared to a taper angle of 86.degree.
for an exhaust system of the related art, a taper angle of
89.degree. and ideal formation are possible with the exhaust system
of the present invention. Here, taper angle means the angle formed
by the Si wafer and the side wall of the hole (refer to FIG.
58).
[0562] (Embodiment 31)
[0563] This embodiment shows the case where the present invention
is applied to a magnetron sputtering device.
[0564] The structure of this device is the same a FIG. 54, so a
further drawing is omitted. Here, a target is the substrate 5404 to
be plasma processed mentioned in FIG. 54. A dipole ring magnet
having a plurality of permanent magnets aligned in a ring shape is
used as magnetic field applying means, but this is not limiting.
Material of the inner walls of the container are a material
discharges a little discharge gas (such as moisture) as possible,
so it is AIN in this case. However, high frequency power applied to
the electrode I was 43.0 MHz, the frequency applied to the
electrode II was 13.56 MHz, and the frequency applied to the
auxiliary electrode B was 100 MHz. The high frequencies applied to
the respective electrodes are not limited to those described above,
but the frequency applied to the auxiliary electrode B is
preferably set high so that the self bias potential for electrode B
is low and sputtering of the auxiliary electrode B itself can be
avoided.
[0565] Only the exhaust system of the above described device was
modified and the major difference of the exhaust system of the
present invention was evaluated in comparison to the exhaust system
of the related art (exhaust system in one direction only, i.e., the
method disclosed in FIG. 43(a)). Evaluation was carried out by
generating plasma using Ar as carrier gas under a pressure of 10
mTorr, carrying out sputtering, measuring the distribution of cut
away amount of the Al target, and comparing the state of plasma
generated in the vicinity of the target. A single crystalline Si
wafer (6 inches) was used as the substrate to be subjected to film
formation.
[0566] The results of this evaluation are shown in FIG. 59. From
these results the following point becomes clear.
[0567] (1) In this embodiment, by increasing the gas flow amount
when the pressure inside the container is 10 mTorr to 1.5 sccm, the
in-plane uniformity of the cut away amount is improved. This is
considered to be due to the fact that a uniform exhaust rate and
gas flow are realized in the vicinity of the target.
[0568] Al was used as the target, but the same results were also
confirmed with Cu.
[0569] (Embodiment 32)
[0570] This embodiment shows the case where the present invention
is applied to a plasma oxidation device for oxidizing the surface
of a substrate at low temperature in a plasma device using a radial
line slot antenna capable of uniformly supplying gas in a large
flow amount.
[0571] The structure of this device is the same as FIG. 53, and so
a further drawing will be omitted.
[0572] Description will be given for the case where an Si wafer is
used as the substrate and a gate oxidation film is formed by direct
oxidation of the Si wafer surface using O.sub.2 Ar and O.sub.2 are
used as the source material gas. It is also possible to use Xe
instead of Ar as a carrier gas. It is also possible to add He etc.
to the mixed gas comprising Ar and O.sub.2 FIG. 60 is a schematic
diagram showing a combination of a cross section of an element
formed with this embodiment, and a system for measuring withstand
voltage of the element. In FIG. 60, the element whose withstand
voltage was measured comprises a substrate 4001 formed of an n-type
Si wafer, a field oxidation film 4002, a gate oxidation film 4003,
and a gate electrode 4004. Also, reference numeral 4005 is a probe
used in measurement of the withstand voltage, reference numeral
4006 is a voltmeter, reference numeral4007 is voltage applying
means, and reference numeral 4008 is an ammeter.
[0573] The formation and withstand voltage measurement of the
element shown in FIG. 60 was carried out through the following
sequence of events. After a field oxidation film 4002
(thickness:800 mn) comprising SiO.sub.2 has been has been formed on
the n-type Si wafer using a thermal oxidation method
[(H.sub.2+O.sub.2) gas, H.sub.2=1 l/min, O.sub.2=1 l/min,
temperature of object to be processed=1000.degree. C.] part of the
field oxidation film 4002 is subjected to etching processing and
the surface of the n-type Si wafer 4001 is exposed.
[0574] Only the exposed surface of the n-type Si wafer 4001 was
subjected to direct nitridation using the plasma device of the
present invention to form the gate oxidation film 4003 (surface
area=1.0.times.10.sup.-4 cm.sup.2) formed of SiO.sub.2. The film
formation conditions at this time were: film formation gas
(Ar+O.sub.2); gas pressure 30 mTorr; partial pressure ratio
Ar:O.sub.2=98%:2%; microwave power 700W; oxidation processing time
20 minutes; the substrate was held in an electrically floating
state and the temperature of the object to be processed was
430.degree. C. However, the film formation conditions are not thus
limited.
[0575] A gate electrode 4004 (thickness 1000 nm) formed of Al was
formed on the field oxidation film 4002 and the gate oxidation film
4003 using a vapor deposition method.
[0576] The probe 4005 was brought into contact with the gate
electrode 4004, a d.c. voltage was applied to the object to be
processed 40001 formed of the n-type Si wafer, through the gate
electrode 4004, and the potential at which the gate oxidation film
4003 suffered dielectric breakdown (namely, withstand voltage) was
measured using the voltmeter 4006.
[0577] FIG. 61 is a graph showing the results of measuring
withstand voltage. FIG. 61(a) shows the case of a gate insulation
film formed by with the device of the present invention, while FIG.
61(b) shows the case of a gate insulation film formed by with the
device of the related art.
[0578] FIG. 62 shows a plan view of a plasma device using a radial
line slot antenna having the exhaust system of the related art. The
only difference from a device using the exhaust system of the
present invention is the exhaust system. The exhaust system of the
present invention has a comparatively wide space provided above the
vacuum pump, and expulsion in carried out from a plurality of
vacuum pumps arranged spaced substantially equal distances apart at
the side of the substrate, it is possible to have a gas flow
uniformly above the substrate in a rotational direction
substantially without lowering the gas conductance. Specifically,
it becomes possible to cause a large amount of gas to flow up to
the capacity of the vacuum pump, and it is possible to handle ultra
high speed processing of a large diameter substrate. Conversely,
because the exhaust system of the related art uses vacuum pump
expulsion in only one direction, the space above the vacuum pump is
narrow and the gas conductance is lowered, it is not possible to
realize uniform gas flow above the substrate. As a result, it is
not possible to make a large amount of gas flow and it is
impossible to handle high speed processing of a large diameter
substrate.
[0579] In FIG. 61, the horizontal axis represents withstand voltage
and the vertical axis represents frequency of occurrence of
elements that obtained each withstand voltage. For example, the bar
graph of the horizontal axis 10MV/cm is the frequency of occurrence
of elements having a withstand voltage in the range 9.5-10.4 MV/cm.
The number of elements measured was 30 in each of FIG. 61(a) and
61(b). From FIG. 61 the following point becomes clear.
[0580] Elements formed using the device provided with the exhaust
system of the related art have a wide distribution of withstand
voltage (namely bad film quality uniformity), and an average
withstand voltage of 10.3 Mv/cm [FIG. 61(b)].
[0581] Elements formed using the device of the present invention
have a narrow distribution of withstand voltage (namely good film
quality uniformity), and a high average withstand voltage of 11.5
MV/cm can be obtained, which means that the film quality of a gate
oxidation film is improved [FIG. 61(a)].
[0582] FIG. 63 is a graph showing distribution of film thickness of
the inner surface of wafer surface of the Si oxidation film. The
horizontal axis represents distance from the center of the wafer
and the horizontal axis represents film thickness of the direct
oxidation film., The film thickness of the direct oxidation films
formed with the device provided with the exhaust system of the
related art has low uniformity. On the contrary, the film thickness
of direct oxidation films formed with the device of the present
invention are almost constant at the wafer surface, and uniformity
is high. Accordingly, since it is possible to form oxidation films
having high uniformity and high withstand voltage it was confirmed
that it was possible to stably manufacture elements having
excellent withstand voltage.
[0583] In this embodiment, the device of the present invention has
been applied to a plasma oxidation device for oxidizing a Si
surface of a substrate at low temperature, but it is not limited to
a Si surface and it was confirmed that it was also possible to
obtain oxidation films having high uniformity with metallic
surfaces.
[0584] (Embodiment 33)
[0585] This embodiment shows the case where the present invention
is applied to a plasma nitriding device for nitriding the surface
of a substrate at low temperature in a plasma device using a radial
line slot antenna capable of uniformly supplying gas in a large
flow amount.
[0586] The structure of this device, as well as the plasma device
using a radial line slot antenna provided with the exhaust system
of the related art, are the same as embodiment 3, and so will be
omitted.
[0587] Similarly to embodiment 3, a Si wafer is used at the
substrate, and description will given for the case where the
surface of the Si wafer is subjected to direct nitridation using
N.sub.2, and a gate nitridation film is formed.
[0588] FIG. 64 is a schematic drawing showing a combination of a
cross section of an element formed in the present embodiment and a
system for measuring dielectric breakdown injection charge amount
for the element. In FIG. 64, the element that has had dielectric
breakdown injection charge amount measured comprises an object to
be treated 5001 made of an n type Si wafer, a field oxidation film
5002, a gate nitride film 5003 and a gate electrode 5004. Also,
reference numeral 5005 is a probe used in measurement of dielectric
breakdown injection charge amount, reference numeral 5006 is a
voltmeter, reference numeral 5007 is a constant current source and
reference numeral 508 is an ammeter. Element formation and
dielectric breakdown injection charge amount measurements shown in
FIG. 64 were carried out using the following procedure.
[0589] After a field oxidation film 5002 (thickness:500 nm) formed
of SiO.sub.2 has been formed on the n type Si wafer 5001 using a
thermo oxidation method [(H.sub.2+O.sub.2 gas), H.sub.2=1 l/min,
O.sub.2=1 l/min, temperature of object to be treated=1000.degree.
C.], part of the field oxidation film 5002 was subject to etching
processing and the surface of the n type Si wafer was exposed.
[0590] Only the exposed surface of the field oxidation film 5002
was direct nitrided using the plasma device of the present
invention, and the gate nitride film 5003 (surface area
1.0.times.10.sup.-4 cm.sup.2, thickness 5.6 nm) formed of
Si.sub.3O.sub.4 was formed. The film forming conditions at this
time were film forming gas (Ar+N.sub.2), gas pressure 30 mTorr,
partial pressure ratio Ar/N.sub.2=99.7%-90%/0.3%-10%, microwave
power 700W, nitriding processing time 20 min, the object to be
treated was held in an electrically floating state, and the
temperature of the object to be treated was 430.degree. C. However,
the film formation conditions are not thus limited.
[0591] A gate electrode 5004 of Al (thickness 1000 nm) was formed
on the field oxidation film 5002 and the gate nitride film 5003 by
a vapor deposition method.
[0592] The probe 5005 was brought into contact with the gate
electrode 5004, a constant current was applied to the object to be
treated 5001 formed of the n type Si wafer via the gate electrode
5004 using the constant current source 5007 so the electron density
became 100 mA/cm.sup.2, and time taken for the gate nitride film
5003 to suffer dielectric breakdown was measured. The electron
density value multiplied by this time is the dielectric breakdown
injection charge amount.
[0593] FIG. 65 is a graph showing the results of measuring the
dielectric breakdown injection charge amount.
[0594] In FIG. 65, the horizontal axis represents injection charge
amount, and the vertical axis represents the frequency of
occurrence of elements obtaining each injection charge amount. The
number of elements measured was 20 in each of the related art
method and the present invention. From FIG. 65 the following point
becomes clear.
[0595] In the elements manufactured using the device of the related
art, distribution of injection charge amount was wide (namely film
quality was bad), and average charge injection amount was
59.3C/cm.sup.2.
[0596] In the elements manufactured using the device of the present
invention, the distribution of injection charge amount was narrow
(namely film quality was good) and it was possible to obtain a high
average load injection amount of 572C/cm.sup.2, so it will be
understood that film quality of the gate oxidation film was
improved.
[0597] FIG. 67 is a graph showing results of measuring the barrier
function of the direct oxidation film. Si wafers that have been
subjected to direct oxidation using a device provided with the
exhaust system of the related art and a device provided with the
exhaust system of the present invention were bleached for five
hours in a 100% O.sub.2 atmosphere at 600.degree. C., and then
measured using an X-ray photoelectron spectroscope. In FIG. 67, the
horizontal axis represents the time for which the Si wafer
subjected to direct oxidation was bleached in the O.sub.2
atmosphere, and the vertical axis represents the peak surface area
of SiO.sub.2 that has been chemically shifted by oxidation of the
surface. From the drawing, the following point becomes clear.
[0598] With the surface of the Si wafer subjected to direct
oxidation using the device of the related art, the peak surface
area increases with time, and it is oxidized in the O.sub.2
atmosphere with passage of time. From this it will be understood
the direct oxidation film formed using the device of the related
art has a low barrier function against oxygen.
[0599] With the surface of the Si wafer subjected to direct
oxidation using the device of the present invention, there is no
increase in peak surface area with time, and it is not oxidized in
the O.sub.2 atmosphere with passage of time. From this it will be
understood the direct oxidation film formed using the device of the
present invention has a high barrier function against oxygen.
[0600] FIG. 68 shows the relationship between amount of oxygen and
carbon included within the direct oxidation film formed from the
film formation atmosphere, and total flow amount of process gas.
From the drawing the following point becomes clear.
[0601] As the total flow amount of process gas increases, the
amount of oxygen and carbon included within the formed direct
oxidation film decreases, and it becomes possible to form a direct
oxidation film having low oxygen and carbon contamination.
[0602] This means that the device of the present invention enables
film formation while there is a large flow amount of gas, and so is
suitable for the formation of direct oxidation films having low
oxygen and carbon contamination.
[0603] Accordingly, by carrying out direct oxidation using the
plasma processing device of the present invention, it is possible
to suppress the concentration of impurities within a film, and to
form an oxidation film having high film quality uniformity and high
injection load amount, with uniform distribution of film thickness,
and a high barrier properties, and so it was confirmed that it was
possible to stably manufacture elements having excellent
characteristics.
[0604] Also, in this embodiment, the device of the present
invention has been applied to a plasma oxidation device for
oxidizing the Si surface of a substrate at low temperature, but it
is not limited to an Si surface and it was confirmed that it was
possible to obtain metallic oxidation films with high uniformity if
applied to oxidation of a metallic surface such as Ta, W, Al, Ti,
etc.
[0605] (Embodiment 38)
[0606] This embodiment shows a case where the device of the present
invention is applied to a plasma CVD device for forming a diamond
film on a substrate, in a plasma device using a radial line slot
antenna capable of uniformly supplying a large gas flow amount.
[0607] The structure of this device is the same as that of
embodiment 3, and so will be omitted.
[0608] A diamond thin film has excellent mechanical, electrical
thermochemical and optical characteristics, and is mostly noted for
the fact that its semiconductor characteristics can be controlled
by adding appropriate impurities.
[0609] In this embodiment, the case will be described where a thin
diamond film is formed for the intention of application to a mask,
for use in X-ray lithography anticipated as the next generation
manufacturing technology for ULSI silicon.
[0610] FIG. 69 shows a structural example of a mask for use with an
X-ray diffractometer. A circuit pattern for transcribing is formed
in an absorber of a central square section of the drawing. A
parallel beam X-ray is incident from a substrate side, and X rays
pass through a part of the central square section where there is no
absorber and are projected onto to a Si wafer to be subject to
pattern formation, not shown in the drawings, located on the
absorber side. The diamond thin film utilized as a support layer
for the absorber must be transparent, have a smooth surface and
have uniform characteristics at the inner surface.
[0611] In this embodiment, formation of a diamond thin film on a Si
wafer has been illustrated. In the following, the method will be
described.
[0612] An Si substrate from which surface contaminants (particles,
organic matter, metal) and a natural oxidation film have been
removed is introduced into a chamber. After loading, the diamond
thin film is formed to a thickness of 1-2 .mu.m using the
aforementioned device. First of all, the surface of the Si
substrate is subjected to carbonization processing in an
Ar/H.sub.2/CH.sub.4 or Ar/H.sub.2/CO.sub.2 atmosphere, and then the
Si substrate is negatively biased and a diamond crystal kernel is
generated on the Si substrate. After this processing, a diamond
thin film is formed to a thickness of 1-2 .mu.m in a
Ar/H.sub.2/CH.sub.4/O.sub.2 or Ar/H.sub.2/CO.sub.2/O.sub.2
atmosphere. It is possible to replace Ar with Xe. The chamber
pressure at the time of processing is 3-500 mTorr, process gas flow
amount can be made up to 3SLM, and the Si wafer is temperature
controlled to 300-700.degree. C. With the device of the present
invention, it is possible to generate high density and uniform
plasma over a large surface area, and by providing a shower plate
the supply of source material gas is made uniform and it is
possible to uniformly form a film on a large diameter substrate.
Also, by narrowing the processing space and uniformly and rapidly
expelling a large flow amount of process gas it is possible to
rapidly remove reaction by-products, which means that reaction
by-products such as non diamond components that have been uniformly
etched by atomic hydrogen are rapidly expelled and a high quality
diamond film can be generated.
[0613] Results of evaluating the diamond thin film formed to a
thickness of 2 .mu.m in the Si wafer are shown in Table 2.
2TABLE 2 Results of Diamond Film Evaluation film thickness, inside
4 inch wafer (total 2.00 .+-. 0.01 .mu.m ellipsometric film
thickness) Surface roughness 5 nm permeability (measurement after
removal 90% at 633 nm of Si substrate)
[0614] Permeability was measured after the central section of the
rear surface (the opposite side to the surface on which the thin
film was formed) of the Si wafer was removed to expose the diamond
thin film. The measurement system is shown in FIG. 70.
[0615] FIG. 71 shows variation of surface roughness and
permeability when the total flow amount of process gas was changed.
In the related art, machine polishing was carried out after film
formation. By using the plasma device of the present invention,
reaction by-products such as non diamond components that have been
uniformly etched by atomic hydrogen are rapidly expelled and a high
quality diamond film can be generated.
[0616] (Embodiment 39)
[0617] This embodiment shows a case where the present invention is
applied to a magnetron sputtering device.
[0618] A structural drawing of this embodiment is the same as that
for embodiment 31 and so will be omitted. As described in
embodiment 5, amorphous Ta.sub.4B can be applied as a absorber
material of a mask for X-ray lithography. As described in
embodiment 5, after a flat thin diamond film has been formed, a
film of Ta.sub.4B is continuously formed using a cluster tool,
without coming into contact with the atmosphere in a clean room at
all.
[0619] A characteristic of the cluster tool is that by connecting
between each process chamber using an Ar or N.sub.2 tunnel, thin
film formation can be carried out continuously under an extremely
pure atmosphere without exposing the semiconductor, metal, or
insulator on the wafer to the atmosphere at all. Also, each process
chamber achieves an ultra high vacuum state of the ultimate vacuum
of 10.sup.-10 Torr, but at the time of conveying the wafer, a
number of mTorr to several tens of Torr is maintained using very
pure Ar or N.sub.2, and contamination of the wafer surface by
organic matter or moisture etc. is prevented. Further, conveyance
between each cluster is carried out using a port encapsulated with
N.sub.2 or dry air, and wafer cleansing and lithographic processing
is also carried out in an N.sub.2 or dry air atmosphere, so that it
is possible to carry out processing that completely excludes all
sorts of impurity elements from the atmosphere.
[0620] In this embodiment, formation of an amorphous Ta.sub.4B film
on the Si wafer and on the diamond thin film on the Si wafer is
carried out. The method of carrying out this film formation will be
described below.
[0621] Ta.sub.4B is formed to a thickness of 0.5-1 .mu.m either by
film formation on a Si wafer from which surface contaminants
(particles, organic matter, metal) have been removed, or by
continuous formation of a diamond film. The structure of this
embodiment is the same as FIG. 44 and will be omitted.
[0622] A compound of titanium and boron having a ratio of number of
atoms of 4:1 is used as the sputtering target. Sputtering is
carried out in an Ar or Xe atmosphere. The chamber pressure at this
time is 3-500 mTorr. A process gas flow amount up to 3SLM is
possible.
[0623] The results of evaluating the Ta.sub.4B film formed on the
Si wafer and on the 2 .mu.m diamond thin film on the Si wafer to a
thickness of 1 .mu.m are shown in Table 3. From these results the
following becomes clear.
[0624] (1) Using the plasma device of the present invention, film
formation with high in-plane uniformity can also be obtained for a
large diameter substrate.
3TABLE 3 Evaluation results for amorphous Ta.sub.4B On Si substrate
On diamond thin film Film thickness, inside 4 000 .mu.m .+-. 0.008
.mu.m 000 .mu.m .+-. 0.021 .mu.m inch substrate (Total stepped film
thickness Surface roughness (atomic 1 nm 6 nm force microscope)
[0625] (Embodiment 40)
[0626] This embodiment shows a case where the present device is
applied to a plasma CVD device for forming a polycrystalline
silicon thin film on the substrate in a plasma device using a
radial line slot antenna capable of uniformly supplying a large
flow amount of gas.
[0627] The structure of this device is the same as embodiment 3,
and will be omitted.
[0628] Description will be given for the case where a thin film is
formed on a glass substrate. The foundation substrate is not
limited to a glass substrate and the material can also be amorphous
such as SiN.sub.x, or SiO.sub.2. As uses for the polycrystalline
silicon thin film, it is possible to utilize it as an active layer
of a transistor, or a gate electrode etc. SiH.sub.4, Xe was used as
the source material gas, but is not limited to this combination. It
is also possible to replace SiH.sub.4 with Si.sub.2H.sub.4, and to
replace Xe with Ar or H.sub.2 etc.
[0629] Evaluation was carried out with the gas flow amount ratio
for Xe and SiH.sub.4 set to 100:1.
[0630] Microwave power was 1600W, and total gas flow amount of the
gas introduced into the process chamber was changed from 300 sccm
to 3000 sccm. The polycrystalline silicon was formed on a 300 mm
glass substrate, and the surface plasma, uniformity and
polycrystalline silicon crystallite size were measured. The
substrate temperature was set to 300.degree. C. This is just one
example of the processing conditions for illustrating the effects
of the present invention, but these conditions are not
limiting.
[0631] FIG. 72 shows the dependency of surface roughness of the
film formed polycrystalline silicon thin film on total gas flow
amount. Measurement was carried out using an atomic force
microscope (AFM). It can be seen that if the total gas flow amount
is increased, surface roughness is lowered.
[0632] FIG. 73 shows the dependency of in-plane uniformity on the
glass substrate of the film formed polycrystalline silicon thin
film on total gas flow amount. It will be understood that the
in-plane uniformity is also improved as total gas flow is
increased.
[0633] FIG. 74 shows the dependency of crystallite size of the film
formed polycrystalline silicon film on total gas flow amount. The
crystallite size was calculated based on the scheller method using
a Si peak width at half height obtained by an X-ray thin film
method. It will be understood that crystallite size increases
accompanying increase in total gas flow amount.
[0634] FIG. 75 shows dependency of in-film hydrogen amount of the
film formed polycrystalline silicon thin film on total gas flow
amount. Measurement of the in-film hydrogen amount was carried out
using FT--IR, and is represented by relative values. It will be
understood that accompanying increase in total gas flow amount
removal of reaction by-products was promoted and in-film hydrogen
amount was decreased.
[0635] FIG. 76 shows the dependency of specific resistance of a
film on total gas flow amount, in the case of P dopant with
PH.sub.3 added to a process gas of Xe and SiH.sub.4. Evaluation was
carried out with the flow amount ratio of Xe:SiH.sub.4:PH.sub.3
fixed to 100,000:1000:1, but it is not limited to these values. It
will be understood that accompanying increase in total gas flow
amount the specific resistance of the film becomes smaller, and the
activation rate of the dopant is increased. The above effects were
also conformed in the case of dopant using addition of hydrides
such as AsH.sub.3 and B.sub.2H.sub.6 instead of PH.sub.3.
[0636] As has been described above, using the present invention, by
being able to uniformly expel a large flow amount, removal of
reaction by-products is promoted and in-plane uniformity is
improved, surface roughness is reduced, and it is possible to form
a high quality polycrystalline silicon thin film having large
crystallite size.
[0637] (Embodiment 41)
[0638] This embodiment shows a case where the present device is
applied to a plasma CVD device for forming a Si.sub.3N.sub.4 thin
film on the substrate in a plasma device using a radial line slot
antenna capable of uniformly supplying a large flow amount of
gas.
[0639] The structure of this device is the same as embodiment 32,
and will be omitted.
[0640] The Si.sub.3N.sub.4 film can be used as a gate insulation
film for a TFT etc, a LOCOS mask or as a passivation film, or the
like. SiH.sub.4, Xe and N.sub.2 are used as the source material
gas, but this combination is not limiting. It is possible to
replace Si.sub.2H.sub.4 with SiH.sub.6, to replace Xe with Ar and
to replace N.sub.2 with NH.sub.3. The ratio of SiH.sub.4:Xe:N.sub.2
is set to 1:100:5. Microwave power was 1600W, while pressure inside
the process chamber was 300 mTorr, a total gas flow amount was
changed from 300 sccn to 3000 sccm. A SiN.sub.x thin film was
formed on a 300 mm glass substrate, and the uniformity and
withstand voltage of the film were measured. Substrate temperature
was set to 300.degree. C.
[0641] This is just one example of the processing conditions for
illustrating the effects of the present invention, but these
conditions are not limiting.
[0642] FIG. 77 shows the dependency of in-plane uniformity on the
glass substrate of the film formed Si.sub.3N.sub.4 thin film on
total gas flow amount. It will be understood that accompanying
increase in total gas flow amount, the in-plane uniformity is also
improved.
[0643] FIG. 78 shows dependence of withstand voltage of the film
formed Si.sub.3N.sub.4 film on the total gas flow amount. Withstand
voltage was measured by making a dedicated TEG. It will be
understood that withstand voltage increases accompanying increase
in total gas flow amount.
[0644] FIG. 79 shows dependence of atomic level compositional ratio
of Si to N in the film formed Si.sub.3N.sub.4 film on the total gas
flow amount. Measurement was carried out using X-ray photoelectron
spectroscopy. It will be understood that accompanying increase in
total gas flow amount, removal of reaction by-products was promoted
and the atomic level composition of the Si.sub.3N.sub.4 approached
an ideal compositional ratio for Si and N of 3:4.
[0645] As has been described above, using the present invention, by
being able to uniformly expel a large flow amount, removal of
reaction by-products is promoted and in-plane uniformity is
improved, and it is possible to form a high quality SiN.sub.x thin
film having high withstand voltage.
[0646] (Embodiment 42)
[0647] This embodiment shows a case where the present device is
applied to a plasma CVD device for forming a dielectric thin film
having low fluorocarbon type gas on the substrate in a plasma
device using a radial line slot antenna capable of uniformly
supplying a large flow amount of gas.
[0648] The structure of this device is the same as embodiment 32,
and will be omitted.
[0649] Description will be given for the case where a dielectric
thin film having low fluorocarbon type gas is formed as an
interlayer insulation film between wiring layer of a semiconductor
element.
[0650] A wafer on which first layer AlCu wiring is to be patterned
is introduced into a cluster tool. In this process, all processing
up to formation of a second layer AlCu film is carried out by a
cluster tool. This cluster tool is the same as embodiment 6 and
will be omitted.
[0651] After loading, surface processing of the first layer wiring
surface is carried out using a mixed gas of Ne/F2. Ne/F2 is
introduced into this microwave device, plasma is generated inside
the chamber, the wafer surface is bleached with plasma for about 5
minutes and fluoriding processing is carried out. A dielectric thin
film having low fluorocarbon type gas is then formed on the wafer
in the same chamber without a break in the processing.
C.sub.4F.sub.8, H.sub.2, and Ar were used as the source material
gas, but this combination is not limiting. It is possible to
replace C.sub.4F, with CF.sub.4, to replace H.sub.2 with O.sub.2,
and to replace Xe with Ar. The gas flow amount ration for
C.sub.4F.sub.8, H.sub.2, and Ar was set to 1:1:5. The microwave
power was set to 1600W, the pressure inside the process chamber was
set to 10-200 mTorr, and the total gas flow amount was changed from
500 sccm to 3000 sccm. Film formation was carried out on the wafer
and the deposition rate and uniformity (of the deposition rate)
were measured. The wafer temperature was controlled to 250
degrees.
[0652] It goes without saying that the film formation conditions
are not limited to those described above.
[0653] FIG. 80 shows the dependency of the deposition rate of the
film formed fluorocarbon film on total gas flow amount. It will be
understood that if the total gas flow amount is caused to increase,
the removal of reaction by-products is promoted, and deposition
rate is increased, reaching 800 nm/min or more.
[0654] Also, FIG. 81 shows the dependency of in-plane uniformity of
the deposition rate on the total gas flow rate. It will be
understood that by sufficiently increasing the process gas flow
amount improvement can be seen in the wafer in-plane
uniformity.
[0655] As has been described above, by using the plasma device of
the present invention, high speed and uniform film formation is
possible on a large surface area. Also, if film formation for two
wiring layers is carried continuously in the cluster tool without a
break in the process, it is possible to manufacture a semiconductor
having multiple layer wiring.
[0656] (Embodiment 43)
[0657] This embodiment shows a case where the present device is
applied to a plasma CVD device for forming a BST thin film [(Ba,
Sr) TiO.sub.3 thin film] on the substrate in a plasma device using
a radial line slot antenna capable of uniformly supplying a large
flow amount of gas.
[0658] The structure of this device is the same as embodiment 32,
and will be omitted. This process uses a BST film as an insulating
film of a capacitor within a semiconductor element, and within
processes from formation of a lower electrode of the capacitor up
to formation of an upper electrode, it carries out all processes
except for lithography processing and wafer cleansing process
inside a cluster tool. The features of this cluster tool are the
same as embodiment 6 and will be omitted. First of all, the
substrate is loaded into the cluster tool and a poly-Si lower
electrode is formed. An Ru/RuO.sub.x film is also formed. A BST
film is formed without a break in the process.
[0659] In this example, Ba(DPM).sub.2, Sr(DPM).sub.2,
Ti(I--OC.sub.3H.sub.7).sub.4 O.sub.2 and Ar are used as the source
material gas, but this combination is not limiting and it possible
to replace Ar with Xe. Process gas comprising Ba(DPM).sub.2,
Sr(DPM).sub.2, Ti(I--OC.sub.3H.sub.7).sub.4 is introduced into the
device from the gas inlet with Ar as a carrier gas. Also, Ar and
O.sub.2 are introduced into the process chamber at a ratio of 1:2,
as additional gas. Microwave power was set to 1600W and pressure
inside the process chamber was set to 10-200 mTorr, and additional
gas flow amount was changed from 500 sccm to 3000 sccm. At this
time, only the flow amount of the additional gas was caused to
change, and processing was carried out without changing the supply
condition for the Ba(DPM).sub.2, Sr(DPM).sub.2,
Ti(I--OC.sub.3H.sub.7).sub.4. Film formation was carried out on a
300 mm wafer, and deposition rate and uniformity of the deposition
rate were measured. It goes without saying that the film formation
conditions are not limited to these described above.
[0660] FIG. 82 shows the dependency of deposition rate of the BST
film on additional gas flow amount. If additional gas flow is
increased there is a tendency for the deposition rate to decrease.
Also, FIG. 83 shows the dependency of in-plane uniformity of the
deposition rate on the additional gas flow rate. It will be
understood that by sufficiently increasing the process gas flow
amount improvement can be seen in the wafer in-plane uniformity,
and in-plane uniformity of less than .+-.2% is achieved with a 300
mm substrate.
[0661] As has been described above, by using the plasma device of
the present invention formation of a uniform and high quality film
is possible on a large surface area. Also, if film formation of TiN
as an upper electrode is carried out after BST film formation, it
is possible to manufacture a capacitor for use in semiconductor
element.
[0662] In this embodiment, poly-Si, TiN and Ru/RuO.sub.x have
respectively been used as lower and upper electrodes of a capacitor
and a stacked electrode, but it goes without saying that the
present invention can also be applied in the case where Pt, Ta, W,
Mo, Rh, In, InO.sub.x, TiSi.sub.x etc. are used. In this
embodiment, a BST film has been used as a capacitor insulation
film, but it goes without saying that the same effects as in this
embodiment are also obtained in the case where PZT or SrTiO.sub.3
etc. are used.
[0663] (Embodiment 44)
[0664] FIG. 84 is a cross section of a device manufactured using
the present invention.
[0665] All the following processes, except for wafer cleansing and
lithography processes were carried out using a cluster tool.
[0666] Part of the cluster tool is shown in FIG. 85. The
characteristic of this cluster tool is that by connecting between
each process chamber using an Ar or N.sub.2 tunnel, thin film
formation can be carried out continuously under an extremely pure
atmosphere without exposing the semiconductor, metal, or insulator
on the substrate to the atmosphere at all. Also, each process
chamber achieves an ultra high vacuum state of the ultimate vacuum
of 10.sup.-10 Torr, but at the time of conveying the wafer, a
number of mTorr to several tens of Torr is maintained using very
pure Ar or N.sub.2 and contamination of the wafer surface by
organic matter or moisture etc. is prevented. Further, conveyance
between each cluster is carried out using a port sealed
encapsulated with N.sub.2 or dry air, and wafer cleansing and
lithographic processing is also carried out in an N.sub.2 or dry
air atmosphere, and it is possible to carry out processing that
completely excludes all sorts of impurity elements from the
atmosphere.
[0667] An SOI wafer from which an oxidation film in the vicinity of
the surface has been removed is loaded into the cluster tool 6101.
After loading, a Ta thin film is formed to a thickness of 1-50 nm
with a plasma processing device using a uniform horizontal magnetic
field of the present invention shown in FIG. 54. At this time, by
controlling a high frequency applied to the entire surface of the
wafer, ion irradiation energy is controlled and it is possible to
obtain Ta of desirable film quality. Next, the wafer was introduced
into the plasma processing device using the radial line slot
antenna of the present invention shown in FIG. 53, plasma oxidation
was carried out in a Ar/He/O.sub.2, Xe/O.sub.2 or Xe/He/O.sub.2
atmosphere, only the Ta film formed in the previous process was
oxidized and a tantalum oxide thin film 6001 was obtained. The
pressure at the time of plasma oxidation was 3-500 mTorr and the
wafer was temperature controlled to 300-500.degree. C. A Ta thin
film 6002 constituting a gate electrode was also formed to a
thickness of 0-1-2 .mu.m with the plasma processing device using
the uniform horizontal magnetic field of the present invention
shown in FIG. 54. Consecutively, a CVD NSG film was formed to a
thickness of 1-50 nm using the plasma processing device using the
radial line slot antenna of the present invention shown in FIG. 53.
With this cap processing, it is possible to selectively form
tantalum oxide only on the gate side surface, and it is easy to
carry out etching processing at the time of forming contact holes
on the gate electrode with a high selectivity.
[0668] Next, using the plasma processing device using the uniform
horizontal magnetic field of the present invention shown in FIG.
44, gate etching is carried out. The process for forming the
barrier metal in this step is shown in detail in FIG. 85. By using
this device, in-plane uniformity is high even for a large diameter
substrate, and fine processing is possible. High purity ion
injection is carried out in a self aligned manner, and after
activation annealing for 450-550.degree. C. a source drain region
6003 was formed (a). Oxidation was carried out similarly to
previously, as side wall 6004 processing, using the plasma
processing device using the radial line slot antenna of the present
invention shown in FIG. 53 (b).
[0669] After SiO.sub.2 of the Si surface has been removed by wet
etching, a Ta film is formed to 2-100 nm (c). Ta and S/D section Si
of the surface are made amorphous and mixed by I/I, and after that
tantalum silicide 6006 is formed by annealing (d). After that,
patterning is performed (e) and after Ta has been etched using the
plasma processing device using the uniform horizontal magnetic
field of the present invention shown in FIG. 44 (f), a cap
SiO.sub.2 is removed by wet etching (g). After that, barrier metal
formation 6006 is carried out (h). Next, the wafer was introduced
into the plasma processing device using the radial line slot
antenna of the present invention shown in FIG. 53, and plasma
nitridation was carried out in an N2, Ar/N.sub.2, or Xe/N.sub.2
atmosphere. Film thickness was 10-500 nm. The pressure at the time
of plasma oxidation was 3-500 mTorr and the wafer was temperature
controlled to 300-550.degree. C.
[0670] Also, a CVD NSG film 6007 is formed using the plasma
processing device using the radial line slot antenna of the present
invention shown in FIG. 53, flattened by CMP, and contact etching
is carried out using the plasma processing device using the uniform
horizontal magnetic field of the present invention shown in FIG.
44.
[0671] Capacitor formation is carried out by oxidizing a surface
layer to 5-500 nm after film formation of the lower Ta electrode
6008 to a thickness of 0.1-2 .mu.m, forming tantalum oxide 6009,
and film forming the upper Ta electrode 6010 to 0.1-2 .mu.m. These
processes are also carried out with the plasma processing device
using the radial slot line antenna and the plasma processing device
using the uniform horizontal magnetic field of the present
invention.
[0672] After formation of these elements, formation of Cu wiring
6011 is carried out and the device is completed. In the case where
Ta nitride is used as barrier metal between the wiring, a process
for forming barrier metal on the gate electrode is applied
accordingly.
[0673] A tantalum oxide gate insulation FET or tantalum oxide
capacitor formed in this way was electrically evaluated.
[0674] FIG. 86 shows distribution of a subthreshold coefficient of
a tantalum oxide gate insulation MOSFET. A device having only the
gate insulation film formation using the plasma device of the
related art has a largely distributed subthreshold coefficient, but
in the present invention high uniformity is realized.
[0675] The initial failure rate of MOSFETs in the case of carrying
out a process of forming titanium nitride formation, as barrier
metal, using the plasma device of the present invention, and the
initial failure rate of examples that used the present invention,
as well as samples after carrying out heating tests for 24 hours at
700.degree. C. in the atmosphere, are shown in FIG. 87. With the
technique of the related art, initial failure rate at the wafer
edge is low, but Cu used as wiring material in this case diffuses
into imperfect tantalum nitride. In the present invention, the
entire surface of the wafer exhibits a low failure rate.
[0676] FIG. 88 shows in-plane uniformity of the capacitance of a
tantalum oxide capacitor. In the related art, there is a tendency
for film thickness to increase in the radial direction, but with
the present invention it is possible to obtain a uniform
capacitance over the entire surface.
[0677] In this embodiment, an SOI wafer is used as the starting
wafer, but it goes without saying that it is also possible to
obtain the same results in this embodiment if a Si wafer, Si
epitaxial wafer, metal substrate SOI wafer, GaAs wafer or diamond
wafer, or a substrate having a thin film of Si, epitaxial Si, GaAs
or diamond formed on the surface of quartz, glass, ceramics or
plastic etc. are used.
[0678] Ta is used as a MOSFET gate electrode in this embodiment,
but it goes without saying that the same effects can be obtained if
n.sup.+ polysilicon or p.sup.+ polysilicon is used. In this
embodiment a mixed gas of a carrier gas of Ar, Xe, He, etc. and
O.sub.2 is used as oxidation process gas, but it goes without
saying that the same effects can be obtained with this embodiment
if a mixed gas of another carrier gas and an oxide (for example
H.sub.2O, NO.sub.x etc.) is used as the mixed gas.
[0679] In this embodiment, a mixed gas of a carrier gas of Ar, Xe,
etc. and N.sub.2 is used as the nitridation process gas, but it
goes without saying that the same effects can be obtained with this
embodiment if a mixed gas of another carrier gas and a nitride(for
example NH.sub.3 etc.) is used as the mixed gas.
[0680] Ta is used in this embodiment in the upper and lower
electrodes, but it goes without saying that the same effects can be
obtained with this embodiment if Pt, Ru, Ti, W, Mo, RuO.sub.x,
TiN.sub.x WN.sub.x, TaSI.sub.xN.sub.y, TiSi.sub.xN.sub.y,
Wsi.sub.xN.sub.y etc., or a stacked electrode comprising these
materials is used.
[0681] In this embodiment only tantalum oxide has been dealt with
as a MOSFET gate insulation film and capacitor insulation film, but
it goes without saying that the same effects can be obtained with
this embodiment if a stacked insulation film of tantalum oxide and
SiO.sub.2 or Si.sub.3N.sub.4, BST and PZT is used.
[0682] SiO.sub.2 is used in this embodiment as a cap material for
MOSFET gate processing, but it goes without saying that the same
effects can be obtained with this embodiment if a material such as
Si, or Si.sub.3N.sub.4 is used.
[0683] In this embodiment Ta oxidation is carried out as a MOSFET
gate side wall process, but it goes without saying that the same
effects can be obtained with this embodiment if a sidewall is
formed by using this process as a re-oxidation process and using a
new NSG etc.
[0684] In this embodiment formation of Ta, being barrier metal, is
carried out using Ta, but it goes without saying that the same
effects can be obtained as in this embodiment if TaSi.sub.xN.sub.y
is formed using TaSi.sub.x.
[0685] TaN.sub.x is used in this embodiment as a barrier metal but
it goes without saying that the same effects can be obtained with
this embodiment if a material such as TiN.sub.x, WN.sub.x
TaSI.sub.xN.sub.y, TiSi.sub.xN.sub.y or Wsi.sub.xN.sub.y is
used.
[0686] In this embodiment, a mixed logic type device has been
manufactured, but it goes without saying that the same effects can
be obtained with this embodiment if a logic LSI or DRAM etc. are
used independently of each other.
[0687] (Embodiment 45)
[0688] FIG. 89 shows the expel characteristics of a turbo molecular
pump expulsion characteristics of pumps respectively having exhaust
rates of 220, 540 and 1800 l/sec at a low pressure region, and
expel characteristics in the case of expel with four pumps having
an exhaust rate of 220 l/sec are shown. When the exhaust rate is
not fixed by pressure, pump inlet pressure and expel gas flow
amount are proportional. From the drawing it will be understood
that in a high pressure region exhaust rate is decreased
accompanying increased pressure. It will also be understood that
compared to a pump having a small exhaust rate, a pump having a
large exhaust rate has a further decrease in exhaust rate from a
low pressure region. In a pump having a small exhaust rate of 220
l/sec, substantially no decrease in exhaust rate was observed at a
low pressure region of 20-30 mTorr for carrying out etching
processing. That is, a plurality of small diameter pumps having
small exhaust rate are advantageous in that they can cause a larger
flow amount of gas at a low pressure region for carrying out normal
semiconductor processing than a single large diameter pump having a
high exhaust rate.
[0689] (Embodiment 46)
[0690] FIG. 90-FIG. 92 are plan views showing examples of the
plasma device of the present invention used as cluster tools for
carrying out continuous processing by conveying between
vacuums.
[0691] FIG. 90 is a case where rectangular process chambers and a
rectangular wafer conveyance chamber are joined together. Reference
numeral 9001 is a wafer take in chamber, reference numeral 9002 is
a wafer take out chamber, reference numeral 9003 is a process
chamber 1, reference numeral 9004 is a process chamber 2, reference
numeral 9005 is a wafer conveyance chamber, and reference numeral
9006 is a gate valve. The process chambers 1 and 2 are any of the
chambers disclosed in FIG. 44, or FIG. 48-FIG. 54. For example,
process chamber 1 is an etching chamber and process chamber 2 is a
resist ashing chamber. One or a plurality of wafer conveyance ports
are provided inside the wafer conveyance chamber 9005, and wafer
delivery is carried out for the process chamber and the wafer take
in/take out chambers.
[0692] In the example of FIG. 90, miniature process chambers are
efficiently arranged, and the area that the cluster tool occupies
in the clean room is extremely small. It is possible to make the
footprint of a cluster tool for a wafer having a diameter of 300 mm
even smaller than the smallest footprint of a cluster tool for a
wafer of 300 mm in the related art. With the structure of FIG. 90,
the footprint of a cluster tool for a 300 mm diameter wafer is 3.64
mm.sup.2, which is about 0.9 times the footprint of the smallest
cluster tool for a 200 mm diameter wafer in the related art. The
number of chambers connected to the conveyance chamber is not
limited to six.
[0693] FIG. 91 is for a case where rectangular process chambers and
a hexagonal wafer conveyance chamber are joined together. Reference
numeral 9101 is a wafer take in chamber, reference numeral 9102 is
a wafer take-out chamber, reference numeral 9103 is process chamber
1, reference numeral 9104 is process chamber 2, and reference
numeral 9105 is a wafer conveyance chamber. The process chambers 1
and 2 are any of the process chambers disclosed in FIG. 44 or FIG.
46-FIG. 54. For example, process chamber 1 is an etching chamber
and process chamber 2 is a resist ashing chamber.
[0694] Since it is permissible to only locate a single wafer
conveyance port inside the wafer conveyance chamber, the cost is
reduced compared to the case in FIG. 90. On the other hand, the
footprint of the device becomes slightly larger than the case in
FIG. 90. With the structure of FIG. 91, the footprint of a cluster
tool for a 300 mm diameter wafer becomes 4.34 mm.sup.2. This is
about the same as the footprint of the smallest cluster tool for a
200 mm diameter wafer in the related art. The wafer conveyance
chamber is not limited in shape to a hexagon, and the number of
chambers connected to the wafer conveyance chamber is not limited
to six.
[0695] FIG. 92 is for a case where triangular process chambers and
a hexagonal wafer conveyance chamber are joined together. Reference
numeral 9201 is a wafer take in chamber, reference numeral 9202 is
a wafer take-out chamber, reference numeral 9203 is process chamber
1, reference numeral 9204 is process chamber 2, and reference
numeral 9205 is a wafer conveyance chamber. The process chambers 1
and 2 are any of the process chambers disclosed in FIG. 44 or FIG.
48-FIG. 54. For example, process chamber 1 is an etching chamber
and process chamber 2 is a resist ashing chamber.
[0696] Since the number of vacuum pumps is low, the cost is reduced
compared to the cases of FIG. 90 and FIG. 91, and it is possible to
widen a maintenance space of the device. On the other hand, the
footprint of the device is slightly larger than in the case of FIG.
91. With the structure of FIG. 92, the footprint of a cluster tool
for a 300 mm diameter wafer becomes 4.94 mm.sup.2. The wafer
conveyance chamber is not limited in shape to a hexagon, and the
number of chambers connected to the wafer conveyance chamber is not
limited to six. FIG. 90-FIG. 92 are cases where two types of
process chamber are joined together two at a time, but other
combinations are also possible.
[0697] FIG. 93-FIG. 95 show arrangements of wafer conveyance robots
inside the wafer conveyance chamber of FIG. 90. In FIG. 93,
reference numeral 9301 is a wafer take-in chamber, reference
numeral9302 is a wafer take-out chamber, reference numeral 9303 is
a process chamber, reference numeral 6304 is a wafer conveyance
chamber, reference numeral 9305 is a wafer conveyance robot, and
reference numeral 9306 is a wafer withdrawal unit. The wafer
conveyance robot 9305a carries out wafer delivery between the wafer
take-in chamber 9301, the wafer take-out chamber 9302 and the wafer
withdrawal unit 9306a The wafer conveyance robot 9305b carries out
wafer delivery between the process chambers 9303a and 9303c, and
the wafer withdrawal units 9303a and b. The wafer withdrawal unit
9306 has a function of holding one or a plurality of wafers. The
wafer withdrawal unit can also serve to alignand notch positions of
the wafer, or to heat and cool the wafer.
[0698] In the example of FIG. 93, wafer delivery between wafer
conveyance robots is carried out via the wafer withdrawal units,
but the wafers can be delivered directly without installing the
wafer withdrawal units. In the example of FIG. 93, since a
plurality of wafer conveyance robots are provided, wafers can be
taken into and taken out of the wafer take-in/take-out chambers and
each of the processes chambers at the same time. As a result, the
time needed to convey the wafers is shortened and throughput is
increased.
[0699] FIG. 94 is a structure comprising a plurality of the wafer
conveyance chambers of FIG. 93. Reference numeral 9401 is a wafer
conveyance chamber and reference numeral 9401 is a wafer withdrawal
chamber. By varying the number of connected wafer conveyance
chambers 9401 and wafer withdrawal units 9402, it is possible to
arbitrarily vary the number of connected process chambers. It is
also possible to routinely minimize the footprint of the cluster
tool for an arbitrary number of process chambers.
[0700] In FIG. 95, reference numeral 9501 is a wafer conveyance
robot. The wafer conveyance robot 9501 can move in the direction of
the arrows in the drawing, and a single wafer conveyance robot
carries out taking in and taking out of wafers for all wafer
take-in/take out chambers and process chambers. In this example,
since there is only need for a single wafer conveyance robot, the
cost is reduced compared to the case of FIG. 93. On the other hand,
the time need to convey the wafer is lengthened and it is possible
that throughput will be lowered.
[0701] Industrial Applicability.
[0702] As has been described above, according to the present
invention, it is possible to realize a plasma device capable of
forming a high quality and uniform thin film over a large surface
area and at low temperature.
[0703] Also, the technical concept of the present invention is
applicable to various plasma processes, and can realize a general
purpose device, which means that it is also possible to
significantly reduce maintenance costs etc.
* * * * *