U.S. patent application number 09/984052 was filed with the patent office on 2002-04-18 for plasma etching apparatus and plasma etching method.
Invention is credited to Kaji, Tetsunori, Kanai, Saburo, Masuda, Toshio, Suehiro, Mitsuru, Takahashi, Kazue.
Application Number | 20020043338 09/984052 |
Document ID | / |
Family ID | 13056650 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020043338 |
Kind Code |
A1 |
Masuda, Toshio ; et
al. |
April 18, 2002 |
Plasma etching apparatus and plasma etching method
Abstract
A plasma etching apparatus for etching of a sample having an
etching chamber having a sidewall, an exchangeable jacket which is
held inside of the sidewall and a heating mechanism provided
proximate to a top end of the exchangeable jacket for generating
heat which radiates toward an interior of the etching chamber, the
sample being disposed in the etching chamber. An evacuation system
which evacuates the etching chamber, an etching gas supply which
supplies an etching gas into the chamber and a plasma generator
which generates a plasma for performing etching of the sample in
the etching chamber.
Inventors: |
Masuda, Toshio; (Toride-shi,
JP) ; Takahashi, Kazue; (Kudamatsu-shi, JP) ;
Suehiro, Mitsuru; (Kudamatsu-shi, JP) ; Kaji,
Tetsunori; (Tokuyama-shi, JP) ; Kanai, Saburo;
(Hikari-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
13056650 |
Appl. No.: |
09/984052 |
Filed: |
October 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09984052 |
Oct 26, 2001 |
|
|
|
09421043 |
Oct 20, 1999 |
|
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Current U.S.
Class: |
156/345.12 |
Current CPC
Class: |
H01J 37/32504 20130101;
H01J 2237/022 20130101; H01L 21/67109 20130101; H01L 21/67069
20130101; H01L 21/3065 20130101; H01L 21/6831 20130101; H01J
37/32522 20130101 |
Class at
Publication: |
156/345 |
International
Class: |
C23F 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 1995 |
JP |
7-57472 |
Claims
What is claimed is:
1. A plasma etching apparatus for etching of a sample comprising:
an etching chamber having a sidewall, an exchangeable jacket which
is held inside of said sidewall and a heating mechanism provided
proximate to a top end of said exchangeable jacket for generating
heat which radiates toward an interior of said etching chamber, the
sample being disposed in said etching chamber; an evacuation system
which evacuates said etching chamber; an etching gas supply which
supplies an etching gas into said chamber; and a plasma generator
which generates a plasma for performing etching of said sample in
said etching chamber.
2. A plasma etching apparatus for etching of a sample comprising:
an etching chamber having a sidewall, an exchangeable jacket which
is held inside of said sidewall and a heating mechanism provided
proximate to a top end of said exchangeable jacket for generating
heat which radiates toward an interior of said etching chamber, the
sample being disposed in said etching chamber; an evacuation system
which evacuates said etching chamber; an etching gas supply which
supplies an etching gas into said chamber; and a temperature
controller which circulates a heat exchanging medium through an
interior of said exchangeable jacket during etching so as to at
least control a temperature of a surface of said exchangeable
jacket which faces the plasma in said etching chamber within a
predetermined range and enables depositing of a coating layer on
the surface of said exchangeable jacket during etching which
prevents the surface of said exchangeable jacket from being etched
by said plasma.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S. Ser.
No. 09/421,043, filed Oct. 20, 1999, which is a divisional
application of U.S. Ser. No. 09/227,332, filed Jan. 8, 1999, which
is a continuation-in-part application of to U.S. application Ser.
No. 08/611,758, entitled "Plasma Processing Apparatus and Plasma
Processing Method", filed Mar. 8, 1996, now U.S. Pat. No.
5,874,012, by some of the inventors herein, the subject matter of
the aforementioned application being incorporated by reference
herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a plasma etching apparatus
and etching method and, more particularly, to a plasma etching
apparatus and etching method suitable for forming a fine pattern in
the semiconductor manufacture process.
[0003] In the semiconductor manufacture process, the plasma etching
apparatus is widely used in the fine processing processes, for
example, such as film deposition, etching, and ashing. The process
by plasma etching performs the predetermined process by making
processing gas introduced into the vacuum chamber (reactor)
plasmatic by the plasma generation means, performing the fine
processing by making it react on the surface of a semiconductor
wafer, and discharging volatile reaction products.
[0004] In this plasma etching process, the temperatures of the
inner wall of the reactor and wafer and the deposition status of
reaction products on the inner wall greatly affect the process. If
reaction products deposited inside the reactor are peeled off, dust
may be caused, resulting in deterioration of the element
characteristics and reduction of the yield.
[0005] Therefore, in the plasma etching apparatus, to keep the
process stable and control generation of foreign substances, it is
important to control the temperature in the reactor and deposition
of reaction products on the surface.
[0006] For example, in Japanese Patent Application Laid-Open
8-144072, for the purpose of improving the selection ratio in the
dry etching process of a silicon oxide film, a dry etching
apparatus for controlling and holding the temperature of each unit
inside the reactor at a high temperature within a range of
150.degree. C. to 300.degree. C. (desirably from 200.degree. C. to
250.degree. C.) which is higher than the temperature at the etching
stage of 150.degree. C. or more with the accuracy of less than
.+-.5.degree. C. is described. When the temperature of each unit of
the inner surface of the reactor is increased and controlled at a
high value by heating like this, the deposited amount of plasma
polymeric products on the inner surface of the reactor reduces, and
the deposited amount of plasma polymeric products on a
semiconductor wafer increases, and the selection improves.
[0007] In Japanese Patent Application Laid-Open 5-275385, a
parallel plate type plasma etching apparatus in which a heating
means for increasing and keeping the temperature so that reaction
products generated by the plasma etching will not be deposited is
installed on at least one of the clamp ring (workpiece holding
means) and focus ring (plasma centralization means) is described.
As a heating means, a resistance heating element is used.
Deposition of reaction products can be prevented by heating, so
that peeling of reaction products and deposition of particles on
the surface of a workpiece can be reduced.
[0008] As mentioned above, in the plasma etching apparatus, it is
important to control the temperature of the surface of the inner
wall of the chamber and deposition of reaction products on the
surface of the inner wall.
[0009] However, when the temperature of the inner wall surface of
the chamber, particularly the temperature of the side wall surface
having a wide area is set to a high value between 200.degree. C.
and 250.degree. C. or more, the etching characteristic becomes very
sensitive to the temperature of the inner wall surface and a
problem arises that the reproducibility and reliability of the
process are apt to reduce.
[0010] For example, in S. C. McNevin, et al., J. vac. Sci. Technol.
B 15(2) March/April 1997, p. 21, Chemical challenge of submicron
oxide etching', it is indicated that when the side wall temperature
changes from 200.degree. C. to 170.degree. C. in inductive coupling
plasma, the oxide film etching rate increases more than 5%. As a
reason, it is inferred that since the side wall temperature lowers,
much more carbon is adsorbed into the wall, and deposition of
carbon on a wafer reduces, and the oxide film etching rate
increases. As mentioned above, since high density plasma,
particularly, performs a strong interaction with the inner wall of
the reactor in the high temperature zone, deposition of reaction
products on the inner wall surface and composition change of the
surface proceed rapidly due to a change in the temperature balance
inside the reactor and appear as a change in the etching
characteristic.
[0011] Furthermore, in the high temperature zone, the
aforementioned interaction between the plasma and the inner wall
becomes very sensitive to a change in temperature. For example,
when SiO2 is used as a material of the inner wall surface, a
thermodynamic relationship between the etching rate by F atoms of
SiO2 and the wall temperature is reported (D. L. Flamm, et al., J.
Appl. Phys., 50, p. 6211 (1979)), and when this relationship is
applied to a temperature zone of more than 150.degree. C., the
etching rate rapidly increases exponentially when the wall
temperature is between 200.degree. C. and 250.degree. C. or
more.
[0012] Therefore, in such a high temperature zone, the temperature
control requires high accuracy such as .+-.5.degree. C. max.
However, the inner wall surface is exposed to high density plasma,
so that it is not easy to control the wall surface temperature with
high accuracy in such a high temperature zone. To realize it, a
temperature detection means and a heating means such as a heater
and lamp are used for temperature control, though the temperature
control mechanism and means are largely scaled. Furthermore, in
such a high temperature zone, reaction products are not deposited
on the inner wall surface, so that the wall surface is etched and
consumed by plasma. Therefore, it is necessary to periodically
exchange the parts of the inner wall surface and an increase in the
cost of expendable supplies results. Heating requires large energy,
thus the high temperature zone is not desirable also from a
viewpoint of energy consumption.
[0013] The same problem is imposed also by heating the ring around
a wafer and the electrode. When the ring is heated to increase the
temperature thereof, deposition of reaction products can be
prevented, though the heating mechanism such as the resistance
heating element makes the equipment constitution complex. When the
ring and inner wall surface are etched and consumed by plasma even
if deposition of reaction products can be prevented, there is the
possibility that the constitution material itself will become a new
dust source. Furthermore, when the parts of the ring and inner wall
surface are consumed, it is necessary to periodically exchange them
and the running cost of the equipment increases.
[0014] One method for solving such a problem is to protect the
inner wall surface of the chamber by a surface coating layer of a
polymer. For example, in Japanese Patent Application Laid-Open
7-312363, a plasma etching apparatus for keeping the temperature of
the workpiece (article to be processed) holder higher than that of
the wall surface of the chamber and forming a surface coating layer
on the inner wall surface of the chamber is described. By catching
and storing contaminant particles in a polymer film, remaining and
storing of contaminants in the chamber due to reaction products can
be reduced.
[0015] However, the purpose in this case is not to protect the wall
surface but to catch contaminant particles. It is just described
that the temperature for forming a surface coating layer on the
inner wall surface of the chamber is lower than that of a workpiece
(article to be processed) by more than 5.degree. C. and the
temperature range and control accuracy are not taken into account.
The pressure range is a high pressure range such as several
hundreds mtorr (several tens Pa). However, it is inferred that the
deposition temperature of a film changes the composition and
quality of the film and affects the film peeling strength and
occurrence of foreign substances. It is expected that changing of
the deposited film temperature results in occurrence of cracking
and peeling due to repetition of thermal expansion and shrink and
causes foreign substances and the temperature control accuracy is
an important factor. Within a pressure range of several tens mtorr
max. (several Pa max.), it is considered that the film deposition
condition varies due to high ion energy and a longer mean free
distance of molecules, Furthermore, in the aforementioned prior
art, it is necessary to remove the coating layer catching
contaminants from the wall surface of the plasma etching chamber
and it directly affects the throughput of the equipment and the
cost of expendable supplies. However, this respect is not taken
into account.
SUMMARY OF THE INVENTION
[0016] The present invention is designed to eliminate the
difficulties mentioned above and an object of the present invention
is to provide a plasma etching apparatus maintaining the
reproducibility and reliability of the process at a low cost for a
long period of time so as to prevent the etching characteristic
from a change with time by controlling the inner temperature of the
reactor and deposition of reaction products.
[0017] The inventors have given diligent study to the
aforementioned problems and as a result of it, found that when the
inner wall surface temperature in the reactor is controlled to a
temperature sufficiently lower than that of a wafer and a constant
temperature within a pressure range of several Pa max. in the
reactor, a strong coating film is formed on the inner wall surface.
As a result of more detailed analysis, the inventors have
acknowledged that this coating film is polymerized much more when
the temperature at film forming time is lower, and when the
temperature at film forming time is controlled constant, a solid
layer structure is formed, accordingly the film surface is not
peeled off and is damaged and dust is not caused.
[0018] In the above description, that the inner wall surface
temperature in the reactor is "sufficiently lower than that of a
wafer and constant" means that the temperature is controlled with
the accuracy of less than .+-.10.degree. C. within a range lower
than that of a wafer by 5.degree. C. or more, desirably within a
range lower by 20.degree. C. or more. When the temperature of a
wafer during processing is almost within a range from 100.degree.
C. to 110.degree. C., it means that the temperature range is
100.degree. C. or lower, desirably 80.degree. C. or lower.
[0019] On the other hand, in the reactor, there is a part or a
component part where the control in the aforementioned low
temperature zone is difficult. The inventors have given study also
to such a part and as a result of it, found a method for
controlling the temperature and deposition of reaction products on
the surface without using a complicated heating mechanism such as a
heating resistor.
[0020] The present invention is designed on the basis of the
aforementioned acknowledge and provides a plasma etching apparatus
comprising a vacuum processing chamber, a plasma generation device,
a processing gas supply means for supplying gas to the processing
chamber, an electrode for holding a sample to be processed in this
vacuum processing chamber, and an evacuation system for reducing
the pressure of the vacuum processing chamber, which is
characterized in that the processing gas includes at least one kind
of gas having a composition for forming a polymerized film by
plasma discharge, and the processing gas is made plasmatic by
plasma discharge in the processing chamber, and at least one part
of the inner wall surface (or the surface of an internal component
part) in contact with plasma in the processing chamber is
controlled to a constant temperature which is sufficiently lower
than that of a sample, and a strong polymerized film is formed on
the inner wall surface of the processing chamber.
[0021] Another characteristic of the present invention is that the
temperature of the inner wall surface for forming the
aforementioned polymerized film is controlled with the accuracy of
less than .+-.10.degree. C. within a range lower than that of the
sample by 5.degree. C. or more, desirably within a range lower by
20.degree. C. or more.
[0022] Another characteristic of the present invention is that the
processing pressure in the processing chamber is set within a range
from 0.1 Pa to 10 Pa, desirably from 0.5 Pa to 4 Pa.
[0023] Another characteristic of the present invention is that the
member constituting the inner wall surface of the processing
chamber for forming the aforementioned polymerized film has a
structure that it can be easily exchanged.
[0024] Another characteristic of the present invention is that the
apparatus includes a process of controlling the growth of the
aforementioned polymerized film formed on the inner wall surface of
the processing chamber.
[0025] Still another characteristic of the present invention is
that in the plasma etching apparatus comprising a vacuum processing
chamber, a plasma generation device, a processing gas supply means
for supplying gas to the processing chamber, an electrode for
holding a sample to be processed in this vacuum processing chamber,
and an evacuation system for reducing the pressure of the vacuum
processing chamber, the component part (or the inner wall surface)
in contact with plasma in the processing chamber is structured so
that the bias power is applied to at least one part of the
component part, and the heat capacity thereof is made sufficiently
small, and the surface area thereof is made smaller.
[0026] Another characteristic of the present invention is that the
temperature of the component part in contact with plasma in the
processing chamber is adjusted within a range from 100.degree. C.
to 250.degree. C., desirably from 150.degree. C. to 200.degree. C.
and furthermore, the processing pressure is set within a range from
0.1 Pa to 10 Pa, desirably from 0.5 Pa to 4 Pa.
[0027] Another characteristic of the present invention is that the
component part of the inner wall is ring-shaped and the surface
area of the part in contact with plasma is 20% of the total area of
the inner wall of the processing chamber or less.
[0028] Another characteristic of the present invention is that the
component part in contact with plasma in the processing chamber, in
which the bias power is applied to at least one part thereof is
ring-shaped, and the thickness thereof is 6 mm or less, and the
inner diameter thereof is more than the diameter of a sample
[0029] Still another characteristic of the present invention is
that the plasma etching apparatus is structured so that an infrared
absorber is formed in the neighborhood of the side of the component
part of the inner wall which is in contact with plasma and the
temperature of the part is remotely controlled by the infrared
radiation means.
[0030] Another characteristic of the present invention is that the
temperature of the part whose temperature is controlled by the
aforementioned infrared radiation is controlled with the accuracy
of less than .+-.10.degree. C. within a range from 100.degree. C.
to 250.degree. C., desirably from 150.degree. C. to 200.degree.
C.
[0031] Still another characteristic of the present invention is
that in the plasma etching apparatus, the plasma generation
apparatus is a magnetic field UHF band electromagnetic wave
radiation and discharge system.
[0032] According to the present invention, a part of processing gas
is polymerized by plasma discharge and a surface coating layer is
formed by polymer on the part of the inner wall of the processing
chamber which is in contact with plasma or the surface of the part.
By controlling the temperature of the inner wall surface of the
reactor to a constant temperature sufficiently lower than that of a
wafer, the polymerization of the coating layer proceeds and a solid
layer structure can be formed. Therefore, the inner wall surface
will not be etched and consumed by plasma, so that the frequency of
part exchange of the inner wall surface can be reduced and the
running cost can be decreased. Even if the coating layer is exposed
to plasma, peeling and damage are not caused to the surface thereof
because the film composition is dense, so that dust will not be
caused.
[0033] Since the temperature of the inner wall surface is set in a
temperature zone lower than that of a wafer, as compared with a
case that the temperature of the inner wall surface is set in a
high temperature zone of 200.degree. C. or more, the interaction
between plasma and the inner wall surface is weak and not sensitive
to a change in temperature. As a result, the reproducibility and
reliability of the process hardly reduce for a long period of time
and the accuracy of temperature control may be, for example, less
than .+-.10.degree. C. and can be realized comparatively easily
without using a complicated mechanism for temperature control.
[0034] When a polymerized film exceeding a predetermined value is
formed on the inner wall surface, it is necessary to remove this
film. When the equipment is exposed to the air, and the component
part of the inner wall surface of the processing chamber on which
the polymerized film is formed is exchanged, and the equipment is
reoperated, and the film is removed by wet cleaning on an ex-situ
basis after removal from the chamber instead of plasma cleaning,
and the inner wall surface is reproduced, satisfactory results can
be produced such that the non-operation time of the equipment is
reduced, and the throughput is prevented from reduction, and the
cost of expendable supplies can be reduced by reproduction and
repetitive use of parts. When a process of controlling the growth
of the polymerized film is added to the process, the time up to
opening and cleaning of the equipment can be prolonged.
[0035] On the other hand, according to still another characteristic
of the present invention, with respect to a part or component part
for which the temperature control in a temperature zone
sufficiently lower than that of a wafer is difficult, when a
structure that the bias power is applied to at least one part
thereof is installed in the reactor and the heat capacity of the
whole part is made sufficiently small, the whole part can be
controlled in a high temperature zone without using a complicated
mechanism such as a heater and lamp, so that excessive deposition
of reaction products is controlled and an occurrence of foreign
substances caused by peeling of reaction products can be reduced.
When the surface area of the part is made smaller, the effect on
the process can be controlled even if the temperature and surface
condition are changed. Furthermore, when the magnitude of bias
power to be applied to the component part is adjusted and the
temperature is set within a range from 100.degree. C. to
250.degree. C., desirably from 150.degree. C. to 200.degree. C., as
compared with a case that the temperature is set within a high
temperature zone of about 250.degree. C. or more, the process is
not sensitive to a change in temperature, so that there is an
advantage that the temperature change of the component part can be
made smaller to a level that will not substantially affect the
process.
[0036] According to still another characteristic of the present
invention, the temperature of the component part in contact with
plasma in the processing chamber can be controlled more actively
with high accuracy in a high temperature zone using infrared
radiation and gas heat transfer, so that excessive deposition of
reaction products is controlled, and an occurrence of foreign
substances caused by peeling of reaction products can be reduced,
and the effect on the process also can be controlled by controlling
changes in the temperature and surface condition. Furthermore, when
the temperature is controlled with the accuracy of less than
.+-.10.degree. C. within a range from 100.degree. C. to 250.degree.
C., desirably from 150.degree. C. to 200.degree. C., as compared
with a case that the temperature is set within a high temperature
zone of about 250.degree. C. or more, the process is not sensitive
to a change in temperature, so that there is an advantage that the
temperature change of the component part can be made smaller to a
level that will not substantially affect even a finer process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a cross sectional schematic diagram of a plasma
etching apparatus which is an embodiment of the present
invention.
[0038] FIG. 2 is a drawing showing the temperature control method
of a sample holder ring which is an embodiment of the present
invention.
[0039] FIG. 3 is a drawing showing the temperature control method
of a ring which is an embodiment of the present invention.
[0040] FIG. 4 is a drawing showing the temperature control method
of a ring by an infrared lamp which is an embodiment of the present
invention.
[0041] FIG. 5 is a drawing showing the temperature control method
of a ring by a refrigerant which is an embodiment of the present
invention.
[0042] FIG. 6 is a cross sectional schematic diagram of a magnetic
field RIE plasma etching apparatus which is an embodiment of the
present invention.
[0043] FIG. 7 is a cross sectional schematic diagram of a parallel
plate type plasma etching apparatus which is an embodiment of the
present invention.
[0044] FIG. 8 is a cross sectional schematic diagram of an
inductive coupling type plasma etching apparatus which is an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] The embodiments of the present invention will be explained
hereunder with reference to the accompanying drawings.
[0046] FIG. 1 shows an embodiment that the present invention is
applied to a plasma etching apparatus of a magnetic field UHF band
electromagnetic wave radiation and discharge system and is a cross
sectional schematic diagram of the said plasma etching
apparatus.
[0047] In FIG. 1, a processing chamber 100 is a vacuum vessel which
can realize the degree of vacuum of about 10.sup.-6 Torr and the
apparatus has an antenna 110 for radiating electromagnetic waves as
a plasma generation means in an upper part of the processing
chamber and a lower electrode 130 for loading a sample W such as a
wafer in a lower part of the processing chamber. The antenna 110
and the lower electrode 130 are installed opposite to each other in
parallel. A magnetic field forming means 101 comprising
electromagnetic coils 101A and 101B and a yoke 101C is installed
around the processing chamber 100 and a magnetic field having a
predetermined distribution and intensity is formed. By the
interaction of electromagnetic waves radiated from the antenna 110
and the magnetic field formed by the magnetic field forming means
101, processing gas introduced into the processing chamber is made
plasmatic, and plasma P is generated, and the sample W is
processed.
[0048] On a side wall 102 of the processing chamber 100, a jacket
103 for controlling the temperature of the inner surface of the
side wall is held in the exchangeable state. A heat exchanging
medium is circulated and supplied into the jacket 103 from a heat
exchanging medium supply means 104 so as to control the
temperature. The temperature of the jacket is controlled with the
accuracy of less than .+-.10.degree. C. within a range from
0.degree. C. to 100.degree. C., desirably from 20.degree. C. to
80.degree. C. On the other hand, the processing chamber 100 is
evacuated by an evacuation system 106 connected to a vacuum chamber
105 and the inside of the processing chamber 100 is adjusted to a
predetermined processing pressure within a range from 0.1 Pa to 10
Pa, desirably from 0.5 Pa to 4 Pa. The processing chamber 100 and
the vacuum chamber 105 are set at the grounding potential. With
respect to the side wall 102 of the processing chamber 100 and the
jacket 103, the surface treatment such as plasma resistant anodized
aluminum may be carried out on the surface thereof as a thermally
conductive nonmagnetic metallic material including no heavy metal,
for example, such as aluminum.
[0049] The antenna 110 radiating electromagnetic waves comprises a
disc electricity conductor 111, a dielectric 112, and a dielectric
ring 113 and is held by a housing 114 which is a part of the vacuum
vessel. A plate 115 is installed on the surface of the side of the
disc electricity conductor 111 which is in contact with plasma and
a ring 116 is further installed on the periphery thereof.
Processing gas for performing the processes of etching of samples
and film deposition is supplied from a gas supply means 117 at a
predetermined flow rate and mixture ratio, controlled to a
predetermined distribution via many holes provided in the disc
electricity conductor 111 and the plate 115, and supplied to the
processing chamber 100.
[0050] An antenna power source 121 and an antenna high frequency
power source 122 are connected to the disc electricity conductor
111 respectively via filter systems 123 and 124 of the matching
circuit and connected to the ground via a filter 125. The antenna
power source 121 supplies power at a UHF band frequency desirably
within a range from 300 MHz to 900 MHz and electromagnetic waves in
the UHF band are radiated from the antenna 110. On the other hand,
the antenna high frequency power source 122 applies the bias power,
for example, at a low frequency of about 100 kHz or a high
frequency within a range from several MHz to about 10 MHZ to the
disc electricity conductor 111, thus controls the reaction on the
surface of the plate 115 in contact with the disc electricity
conductor 111. Since the plate 115 is opposite to a wafer, it
affects the process most greatly. However, since the bias power is
applied to the surface so as to prevent reaction products from
deposition, the equipment process is stabilized. Furthermore, for
example, when high-purity silicone or carbon is used as a material
of the plate 115 in oxide film etching using CF series gas, the F
radical or CFx radical reaction on the surface of the plate 115 is
controlled and the radical composition ratio is adjusted. The
distance between the under surface of the plate 115 and the wafer W
(hereinafter, it is called the gap) is within a range from 30 mm to
150 mm, desirably from 50 mm to 120 mm.
[0051] The disc electricity conductor 111 is kept at a
predetermined temperature by a temperature control means not shown
in the drawing, that is, by a heat exchanging medium circulating
through it and the surface temperature of the plate 115 in contact
with the disc electricity conductor 111 is controlled. The ring 116
is heated by the bias power from the antenna high frequency power
source 122 and the temperature thereof is controlled. It will be
described later in detail.
[0052] At the lower part of the processing chamber 100, the lower
electrode 130 is installed opposite to the antenna 110. A bias
power source 141 for supplying bias power within a range from 400
kHz to 13.56 MHz is connected to the lower electrode 130 via a
filter system 142 of the matching circuit, controls the bias power
to be supplied to the sample W, and is connected to the ground via
a filter 143.
[0053] The lower electrode 130 loads and holds the sample W such as
a wafer on the top thereof, that is, on the sample loading surface
by an electrostatic chucking device 131. On the top of the
electrostatic chucking device 131, an electrostatic chucking
dielectric layer (hereinafter, abbreviated to an electrostatic
chucking film) is formed. The electrostatic chucking device 131
applies a DC voltage within a range from several hundreds V to
several kv by an electrostatic chucking DC power source 144 and a
filter 145 so as to generate coulomb force acting between the
sample W and the electrostatic chucking device 131 via the
electrostatic chucking film and adsorbs and holds the sample W on
the lower electrode 130 As an electrostatic chucking film, for
example, an dielectric of aluminum oxide or of a mixture of
aluminum oxide and titanium oxide is used.
[0054] Furthermore, the sample W is controlled by a temperature
control means not shown in the drawing so that the surface
temperature thereof is set to a predetermined temperature so as to
control the surface reaction thereof. For that purpose, to the
lower electrode 130, an inert gas, for example, He gas which is set
at a predetermined flow rate and pressure is supplied to enhance
the thermal conductivity between the electrostatic chucking device
131 and the sample W. By doing this, the temperature of a wafer is
controlled within a range from 100.degree. C. to 110.degree. C. at
its maximum.
[0055] A sample holder ring 132 is installed outside the sample W
on the top of the electrostatic chucking device 131. As a material
of the sample holder ring 132, ceramics such as SiC, carbon,
silicone, or quartz is used. The sample holder ring 132 is
insulated from the electrostatic chucking device 131 by an
insulator 133 such as alumina. Furthermore, by leaking and adding a
part of the bias power from the bias power source 141 to the sample
holder ring 132 via the insulator 133, it is possible to adjust the
application of the bias power to the sample holder ring 132 and
control the reaction on the surface thereof. For example, when
high-purity silicone is used as a material of the sample holder
ring 132 in oxide film etching using CF series gas, the F radical
or CFx radical reaction on the surface of the sample holder ring
132 is adjusted by the scavenging action of silicone and
particularly the uniformity of etching on the periphery of a wafer
can be improved. The sample holder ring 132 is heated by the bias
power and cooled by heat transfer gas, thus the temperature thereof
is controlled. It will be described later in detail.
[0056] The plasma etching apparatus in this embodiment is
structured as mentioned above and a concrete process, for example,
when a silicon oxide film is to be etched using this plasma etching
apparatus will be explained hereunder by referring to FIG. 1.
[0057] Firstly, the wafer W which is an object to be processed is
transferred from a sample transfer mechanism not shown in the
drawing into the processing chamber and loaded and chucked on the
lower electrode 130. The height of the lower electrode is adjusted
as required so as to be set to a predetermined gap. Next, the
inside of the processing chamber 100 is evacuated by the evacuation
system 106. On the other hand, gases necessary to the etching
process of the sample W, for example, C4F8 and Ar are supplied to
the processing chamber 100 from the plate 115 of the antenna 110 by
the gas supply means 117 at a predetermined flow rate and mixture
ratio, for example, at an Ar flow rate of 300 sccm and a C4F8 flow
rate of 9 sccm. At the same time, the processing chamber 100 is
evacuated by the evacuation system 106 and the inside of the
processing chamber 100 is adjusted to a predetermined processing
pressure, for example, 1 Pa. On the other hand, a magnetic field of
a predetermined distribution and intensity is formed by the
magnetic field forming means 101. Electromagnetic waves in the UHF
band are radiated from the antenna 110 by the antenna power source
121 and plasma P is generated in the processing chamber 100 by the
interaction with the magnetic field. The apparatus dissociates
processing gas by this plasma P so as to generate radical ions and
further performs the process such as etching to the wafer W by
controlling the antenna high frequency power source 122 and the
bias power source 141. When the etching process is finished, the
apparatus stops the supply of the power and processing gas and
terminates the etching.
[0058] The plasma etching apparatus in this embodiment is
structured as mentioned above and each unit in the reactor,
particularly the inner surface of the side wall 103 and the ring
116, and temperature control of the sample holder ring 132 and
deposition control of reaction products will be explained in detail
hereunder.
[0059] Firstly, the side wall 103 will be explained by referring to
FIG. 1. As already explained, the jacket 103 is held inside the
side wall 102 of the processing chamber 100 and the temperature can
be controlled by a heat exchanging medium.
[0060] The inventors have experimented with an object of oxide film
etching at a pressure of 2 Pa using a mixed gas series of C4F8 and
Ar as a processing gas and as a result of it, we have found that
when the inner wall surface temperature in the reactor is
controlled to a constant temperature which is sufficiently lower
than the temperature (about 100.degree. C.) of a wafer with the
accuracy of less than .+-.10.degree. C. within a range from
25.degree. C. to 80.degree. C., a strong coating film is formed on
the inner wall surface. Within a pressure range of several tens
mtorr max. (several Pa max.) like this, ions of high energy
increase, so that it can be considered that the ion assist effect
in film deposition is increased and a tight film is formed. The
condition of a deposited film is such that when the side wall
temperature is low, a fine and strong film is formed and when the
side wall temperature is high, a slightly rough film is formed. To
make this change of film characteristic quantitatively clear, the
composition (element density ratio) of a film deposited at a side
wall temperature of each of 25.degree. C., 50.degree. C., and
80.degree. C. has been analyzed by the XPS (X-ray photoelectron
spectroscopy) and the following results have been obtained.
1 Side wall temperature C (%) F (96) CF ratio 25.degree. C. 45.6
51.1 0.89 50.degree. C. 43.9 53.8 0.82 80.degree. C. 40.6 58.2
0.70
[0061] The results show that as the side wall temperature lowers,
the film characteristic becomes richer with carbon. Although not
shown above, the analysis of the C1s peak shows that as the side
wall temperature lowers, the bonding of carbon proceeds and the
polymerization also proceeds. It is inferred that this is
macroscopically observed as a fine and strong film.
[0062] During this experiment, the temperature of the side wall
surface is controlled with the accuracy of less than .+-.10.degree.
C., so that it is forecasted that internal stress caused by a
temperature change is not generated during deposition of a film and
the film structure becomes fine. It is confirmed that a solid layer
structure is formed. This film is very fine and strong and even
when a film is deposited tentatively up to a thickness of about 200
microns in the deposition acceleration test, peeling of the film in
the tape peeling test or in the friction test are not observed.
Furthermore, this film is highly resistant to plasma and it is
acknowledged that peeling and damage of the film surface are not
observed even by the processing of plasma and no dust is
caused.
[0063] When the temperature of the inner wall surface of the
reactor is controlled to a constant temperature which is
sufficiently lower than the temperature of a wafer as mentioned
above, a strong deposited film free of occurrence of internal
thermal stress can be formed on the inner wall surface of the
reactor. This film is highly resistant to plasma and peeling of
reaction products and adhesion of particles onto the sample surface
are reduced, so that it acts as a protection film for the inner
wall of the reactor. Therefore, the side wall is free of
consumption and damage, so that the exchange frequency of parts of
the side wall can be reduced and the reduction of running cost
results. Furthermore, since the side wall is protected by the
deposited film, there is no need to use ceramics such as SiC which
is highly resistant to plasma and the cost of parts can be reduced.
If the side wall temperature is particularly controlled within a
range from normal temperature to about 50.degree. C., the energy
for heating the side wall can be reduced, so that it is effective
in energy conservation. As a material of the side wall, a thermally
conductive metal including no heavy metals, for example, aluminum
may be used.
[0064] Since aluminum is exposed in the initial state free of a
deposited film, there is the possibility that the surface will be
damaged and deteriorated by plasma. To prevent it, the surface may
be coated with a highly polymerized material. Or it is also
possible, for example, to anodize the aluminum surface and then
fill fine holes made by the anodizing process with a highly
polymerized material. Needless to say, the hole filling process can
be applied to other than the aluminum anodizing process. When a
polymer film exists on the interface between the aluminum surface
and the deposited film like this, an effect is produced that the
adherence of the aluminum surface and the deposited film is
increased and the deposited film is hardly peeled off. A film may
be excessively deposited depending on the process. If this occurs,
it is possible to execute plasma cleaning in a short time after the
wafer processing so as to control film deposition and keep the film
thickness constant.
[0065] Next, the sample holder ring will be explained. As already
explained in the embodiment shown in FIG. 1, the sample holder ring
132 controls the reaction on the surface thereof by application of
the bias power, thus can make the etching characteristic
particularly on the periphery of a wafer uniform. Although the
sample holder ring 132 is heated by the bias power in this case, it
is necessary to control the applied bias power and temperature so
as to control the reaction and deposition of a film on the surface
thereof. Moreover, it is desirable to be capable of controlling the
applied bias power and temperature without incorporating a
complicated mechanism into the lower electrode incorporated in the
electrostatic chucking device 131. This can be realized by control
of the leakage bias power and the balance between heating by the
bias power and cooling by heat transfer gas. This embodiment will
be explained by referring to the cross sectional view (half on the
right) of the lower electrode 130 shown in FIG. 2.
[0066] The lower electrode 130 holds the sample W by the
electrostatic chucking device 131. The electrostatic chucking
device 131 is insulated from the ground 135 by the insulator 134.
In this embodiment, the sample holder ring 132 is installed
opposite to the electrostatic chucking device 131 via the insulator
133, thus structured so that a part of the bias power supplied from
the bias power source 141 is leaked and added. The bias power to be
applied can be adjusted by the thickness and material of the
insulator 133. By use of such a bias power application structure,
there is no need to install a wiring structure to the sample holder
ring 132 inside the lower electrode 130 and connect another bias
power source to the sample holder ring 132.
[0067] The electrostatic chucking device 131 is kept at a
predetermined temperature by circulation of a temperature control
heat medium (not shown in the drawing). Between the sample W and
the surface of the electrostatic chucking device 131, a flow path
136 of heat transfer gas (for example, He gas, etc.) is formed and
the heat conduction is kept satisfactory by introduction of heat
transfer gas. In this embodiment, flow 136A and 136B of heat
transfer gas are also formed between the sample holder ring 132,
the insulator 133, and the electrostatic chucking device 131. A
part of heat transfer gas for wafer cooling is introduced and the
heat conduction at the contact is kept satisfactory. As a result,
the heat conduction between the sample holder ring 132 and the
electrostatic chucking device 131 kept at a predetermined
temperature is kept satisfactory and the temperature of the sample
holder ring 132 is kept stable. As a result, the temperature change
due to application of the bias power to the sample holder ring 132
is controlled and the surface reaction and sample processing
characteristic in the sample holder ring 132 can be stabilized. At
the same time, deposition of reaction products can be prevented by
heating by the bias power and ion assist, so that peeling of
reaction products and adhesion of particles onto the sample surface
are reduced.
[0068] As mentioned above, in the sample holder ring, the surface
reaction and temperature and deposition of a film can be controlled
by a simple structure by application of the leakage bias power and
the balance between heating by the bias power and cooling by heat
transfer gas and long term stabilization of the process and
reduction of foreign substances can be realized.
[0069] In this embodiment, the heat conduction is assured by heat
transfer gas. However, another heat conduction means, for example,
such as a thermally conductive sheet may be used.
[0070] Next, the antenna 110 will be explained. As already
described in the embodiment shown in FIG. 1, the antenna high
frequency power source 122 is connected to the disc electricity
conductor 111 and the bias power at about 100 kHz or within a range
from several MHz to about 10 MHz is applied. The temperature of the
disc electricity conductor 111 is kept at a predetermined value by
a heat exchanging medium. Therefore, the plate 115 in contact with
the disc electricity conductor 111 is applied with the bias power
and the surface temperature thereof is also controlled. Since the
plate 115 is opposite to a wafer, it affects the process most
greatly. However, when the bias power is applied to this surface so
as to prevent reaction products from deposition and further the
surface reaction by the scavenging action is used using high-purity
silicone as a material of the plate, the process can be
stabilized.
[0071] On the other hand, the ring 116 on the periphery of the
plate 115 is heated by the bias power by the antenna high frequency
power source 122 in the same way as with the plate 115 and moreover
the heat capacity of the ring 116 is made smaller, thus the
responsibility to temperature change is enhanced. This will be
explained by referring to FIG. 3.
[0072] FIG. 3 shows an embodiment showing the temperature control
method for the ring 116. In this embodiment, the ring 116 is
structured so that the shape thereof is made thinner, and a part
thereof covers the plate 115, and the thermal contact with the
dielectric ring 113 and the plate 115 is minimized. When the
antenna high frequency power is applied to the plate 115 in this
case, ions are pulled into the surface of the ring 116 in the
direction of the arrow shown in the drawing by the bias power to
the plate 115. A heating mechanism such a heater and lamp is not
used in this embodiment, so that there is an advantage that the
mechanism will not be complicated.
[0073] The width w of the part of the ring 116 to which the bias
power is applied is set to, for example, 10 mm or more so that the
part can be efficiently heated by the bias power. The thickness of
the ring 116 is set to, for example, 6 mm or less, desirably 4 mm
or less so as to be validly heated by the bias power. When the
shape is made thinner like this, the heat capacity of the ring 115
is made smaller. As a result, the whole ring can be heated almost
within a range from 100.degree. C. to 250.degree. C., desirably
from 150.degree. C. to 200.degree. C. As a result, the deposition
of reaction products is controlled and the occurrence of foreign
substances due to peeling of reaction products can be reduced.
Within this temperature range, the change in surface reaction is
not sensitive to the change in temperature compared with that in a
high temperature zone of about 250.degree. C. or more, so that
there is an advantage that the temperature change in component
parts can be made smaller to such a level that will not
substantially affect the process.
[0074] The thickness of the ring 116 can be decided by the antenna
bias power frequency, the material of the ring 116, and the balance
of the deposition speed of reaction products to the ring 116 so as
to control the film deposition and prevent the ring surface from
sputtering and consuming by ions. As shown in the drawing, it is
possible to make the parts other than the part to be applied with
the bias power thinner and make the heat capacity of the whole ring
smaller. When the heat capacity of the ring 116 is made smaller
like this, the responsibility is satisfactory in a short time at
the initial stage of the process and the temperature rises, so that
the effect on the processing characteristic is small. It is
desirable that the inner diameter d of the ring 116 is larger than
the diameter of a sample. Since the inner diameter of the reactor
is about 1.5 times of the diameter of a sample, when the diameter
of a sample is 300 mm, the width s of the ring is almost within a
range from 50 mm to 70 mm and the surface area thereof is
sufficiently small for the whole inner wall surface of the reactor,
for example, such as 20% or less. When the surface area of parts is
made smaller like this, even if the temperature and surface
condition are changed, the effect on the process can be controlled.
Moreover, since the ring 116 is positioned on the periphery
compared with a wafer, the effect on the process is made more
smaller.
[0075] In the aforementioned embodiment, since passive heating by
plasma is used, a certain degree of temperature change is
unavoidable. This change may affect the etching characteristic due
to fine division of the process though the effect is not actualized
in the current process and if this occurs, a positive temperature
control mechanism by a lamp and heater is required. FIG. 4 shows an
embodiment of a temperature control mechanism by heating of a
lamp.
[0076] In this embodiment, the dielectric ring 113A is structured
so that a part thereof can apply the bias power by the same
structure 116A as that of the ring 116 and furthermore, on the side
of the dielectric ring 113A close to plasma, an infrared absorber
151 for absorbing infrared light and far infrared light, for
example, an aluminum thin film is formed. Infrared light and far
infrared light are radiated from an infrared radiation means 152,
pass through an infrared transmission window 153 and the dielectric
ring 113A, are absorbed by the infrared absorber 151, and heat the
ring 116. The infrared absorber 151 can be remotely heated by
infrared light, so that when the infrared absorber 151 is installed
on the side of the dielectric ring 113A close to plasma, the
temperature of the surface of the dielectric ring 123 exposed to
plasma can be controlled with higher accuracy. The heating
mechanism uses absorption of infrared light, so that there is an
advantage that the responsibility is better compared with heating
by a heating resistor. Furthermore, the dielectric ring 113A is
heated also by the bias power by the bias power application unit
116A, so that the responsibility to temperature is improved.
[0077] On the other hand, the infrared radiation means 152 is
installed in a holder 154. A gap is provided between the holder 154
and the dielectric ring 113A and heat transfer gas for temperature
control is supplied to the gap via a gas supply means 155. Heat
transfer gas is sealed by vacuum sealing means 156A and 156B. The
dielectric ring 113A radiates heat by this gas heat transfer via
the holder 154. Therefore, for example, by heating by the bias
power and lamp at start of the process and radiating heat by gas
heat transfer during the process, the accuracy of temperature
control is improved. As a result, the temperature of the dielectric
ring 123 can be controlled with the accuracy of about .+-.5 to
10.degree. C. almost within a range from 100.degree. C. to
250.degree. C., desirably from 150.degree. C. to 200.degree. C. The
film deposition is reduced at this temperature, so that the
occurrence of foreign substances due to peeling of a film is
controlled. The surface condition of the dielectric ring 113A is in
the region greatly dependent on the temperature, so that the
surface condition is not changed and a plasma process which is
stable over a long period is realized.
[0078] In the embodiments shown in FIGS. 3 and 4, the film
deposition is reduced by heating the ring 116 in contact with
plasma and the dielectric ring 113A. However, the ring in contact
with plasma is controlled to a constant temperature which is lower
than the temperature of a wafer in the same way as with the inner
surface of the side wall explained in FIG. 1 and a stable deposited
film can be formed. FIG. 5 shows this 15 embodiment and the
dielectric ring 113B is controlled almost within a range from
20.degree. C. to 100.degree. C. under temperature control by a
refrigerant.
[0079] In this embodiment, a refrigerant for temperature control is
supplied to a refrigerant flow path 161 installed in the dielectric
ring 113B from a heat exchanging medium supply means 162. The
refrigerant is sealed by a sealing means 163.
[0080] The temperature of the dielectric ring 113B is kept at a
predetermined value by a temperature controller and temperature
detector which are not shown in the drawing. By use of this
constitution, the temperature of the dielectric ring 113B can be
kept almost within a range from 20.degree. C. to 100.degree. C.
during plasma processing. Therefore, a stable and strong film of
reaction products is deposited on the surface of the dielectric
ring 123, so that the surface of the dielectric ring 123 will not
be etched and consumed. When a film is excessively deposited
depending on the process, the film may be kept at a constant
thickness by concurrently using plasma cleaning.
[0081] Each of the aforementioned embodiments uses a plasma etching
apparatus of a magnetic field UHF band electromagnetic wave
radiation and discharge system. However, electromagnetic waves to
be radiated may be, for example, microwaves at 2.45 GHz or waves in
the VHF band almost within a range from several tens MHz to 300 MHz
in addition to the UHF band. The magnetic field is not always
necessary and, discharge of nonmagnetic field microwaves, for
example, is acceptable.
[0082] Furthermore, in addition to the above, the aforementioned
embodiments can be applied to, for example, a magnetron type plasma
etching apparatus using the magnetic field, a plasma etching
apparatus of a parallel plate type capacitively coupled system, or
an inductive coupling type plasma etching apparatus.
[0083] FIG. 6 shows an example that the present invention is
applied to an RIE apparatus (a magnetron RIE apparatus or
magnetically enhanced RIE apparatus). The processing chamber 100 as
a vacuum vessel has the side wall 102, the lower electrode 130 for
loading the sample W such as a wafer, and an upper electrode 201 to
be grounded opposite to it and also has the gas supply means 117
for introducing predetermined gas into the vacuum vessel, the
evacuation system 106 for decompressing and evacuating the vacuum
vessel, an electric field generation means 203 for generating an
electric field between the lower electrode and the upper electrode,
and a magnetic field generation means 202 for generating a magnetic
field inside the vacuum vessel. The magnetic field generation means
202 has a plurality of permanent magnets or coils which are
arranged in a ring-shape on the periphery of the processing chamber
100 and forms a magnetic field almost parallel to the electrodes
inside the processing chamber. The magnetic field generation means
202 makes processing gas plasmatic by the electric field generated
between the electrodes, generates plasma P, and processes the
sample W. Furthermore, in the magnetron RIE, a magnetic field is
formed almost perpendicularly to the electric field by the magnetic
field generation means 202, so that the collision frequency between
electrons and molecules and atoms in plasma increases, and the
plasma density increases, and a high etching characteristic is
obtained.
[0084] In this embodiment, in the same way as with the embodiment
described in FIG. 1, the jacket 103 for controlling the temperature
of the inner surface of the side wall is held by the side wall 102
in the exchangeable state, and a heat exchanging medium is
circulated and supplied into the jacket 103 from the heat
exchanging medium supply means 104, and the temperature of the
jacket is controlled with the accuracy of less than .+-.10.degree.
C. within a range from 0.degree. C. to about 100.degree. C.,
desirably 20.degree. C. to about 80.degree. C. The jacket 103
comprises, for example, anodized aluminum.
[0085] By use of this constitution, the inner wall surface of the
reactor can be controlled to a constant temperature which is
sufficiently lower than the temperature of a wafer, so that a
strong deposited film can be formed on the inner surface of the
side wall of the reactor. This film is highly resistant to plasma
and acts as a protection film for the inner wall of the reactor and
peeling of reaction products and adhesion of particles onto the
sample surface are reduced. Therefore, the side wall is free of
consumption and damage, so that the exchange frequency of parts of
the side wall can be reduced, and the reduction of running cost
results, and there is no need to use ceramics such as SiC which is
highly resistant to plasma, and the cost of parts can be
reduced.
[0086] In this embodiment, in the same way as with the embodiment
described in FIGS. 1 and 2, it is structured so that a part of the
bias power supplied from the electric field generation means 203 is
leaked to the sample holder ring 132 and furthermore, by cooling by
gas heat transfer, the surface reaction and sample processing
characteristic in the sample holder ring 132 can be stabilized. At
the same time, deposition of reaction products can be prevented by
heating by the bias power and ion assist, so that peeling of
reaction products and adhesion of particles onto the sample surface
are reduced.
[0087] FIG. 7 shows an example that the present invention is
applied to a parallel plate type plasma etching apparatus. The
processing chamber 100 as a vacuum vessel has the side wall 102,
the lower electrode 130 for loading the sample W such as a wafer,
an upper electrode 210 opposite to it, and an electric field
generation means 221 for supplying power to the upper electrode 210
and generating an electric field between the electrodes.
Predetermined processing gas is supplied into the processing
chamber 100 by the gas supply means 117 and the vacuum vessel is
decompressed and evacuated by the vacuum system 106. Processing gas
is made plasmatic by the electric field generated between the
electrodes, and plasma P is generated, and the sample W is
processed. The upper electrode 210 is held by a housing 214 with an
electrode plate 211 insulated by insulators 212 and 213. A plate
215 is installed on the side of the electrode plate 211 in contact
with plasma and a shield ring 216 is installed on the periphery
thereof. The shield ring 216 protects the insulators 212 and 213
from plasma, simultaneously increases the plasma density by sealing
the plasma P in the processing chamber 100 in the state that it is
positioned opposite to the sample holder ring 132, and obtains a
high etching characteristic.
[0088] In this embodiment, in the same way as with the embodiment
described in FIG. 1, the temperature of the inner surface of the
side wall 102 is controlled by the jacket 103 with the accuracy of
less than .+-.10.degree. C. within a range from 0.degree. C. to
about 100.degree. C., desirably 20.degree. C. to about 80.degree.
C., so that a deposited film resistant to plasma is formed and acts
as a protection film for the inner wall of the reactor, and
particles can be reduced, and the exchange frequency of parts of
the side wall can be reduced. Also with respect to the sample
holder ring 132, the surface reaction and sample processing
characteristic can be stabilized by the leakage bias power
application structure and gas cooling, and the deposition of
reaction products is prevented, and the occurrence of particles is
reduced. Furthermore, in the same way as with the embodiment shown
in FIG. 3, the shield ring 216 is structured so that the shape
thereof is thin, and a part of the shield ring 216 covers the plate
115, and the thermal contact with other parts is minimized. As a
result, when power is applied to the plate 115, the shield ring 216
is heated by ions due to the self bias power, and the deposition of
reaction products is controlled, and the occurrence of foreign
substances is reduced.
[0089] FIG. 8 shows an example that the present invention is
applied to an inductively coupled type plasma etching apparatus.
The processing chamber 100 as a vacuum vessel has the side wall
102, the lower electrode 130 for loading the sample W such as a
wafer, and a top plate 230 and is decompressed and evacuated by the
vacuum system 106. On the top of the top plate 230, inductive
discharge coils 231 are arranged and high frequency power is
supplied from a high frequency power source 232. Processing gas is
supplied from the gas supply means 117 and made plasmatic by
inductive discharge by the inductive discharge coils 231, and
plasma P is generated, and the sample W is processed. In the
inductive coupling type plasma etching apparatus, silicone is used
as a material of the top elate so as to stabilize the process and
the interaction between plasma and the wall is controlled by a
means, for example, a Faraday shield or a magnetic field, thus even
if the temperature of the side wall is made lower than the
temperature of a wafer, a high etching characteristic can be
obtained stably.
[0090] In this embodiment, in the same way as with the embodiment
described in FIG. 1, the temperature of the inner surface of the
side wall 102 is controlled by the jacket 103 with the accuracy of
less than .+-.10.degree. C. within a range from 0.degree. C. to
about 100.degree. C., desirably 20.degree. C. to about 80.degree.
C. As a result, a deposited film resistant to plasma is formed and
acts as a protection film for the inner wall of the reactor, and
particles can be reduced, and the exchange frequency of parts of
the side wall can be reduced. Also with respect to the sample
holder ring 132, the surface reaction and sample processing
characteristic can be stabilized by the leakage bias power
application structure and gas cooling, and the deposition of
reaction products is prevented, and the occurrence of particles is
reduced.
[0091] In the aforementioned embodiments, the processing object is
semiconductor wafers and the etching process for them is described.
However, the present invention is not limited to it and for
example, it can be applied also to a case that the processing
object is a liquid crystal board and the process itself is not
limited to etching but the present invention can be applied also
to, for example, the sputtering or CVD process.
[0092] According to the present invention, a plasma etching
apparatus maintaining the reproducibility and reliability of the
process at a low cost for a long period of time so as to prevent
the etching characteristic from a change with time by controlling
the inner temperature of the reactor and the wall surface condition
can be provided.
* * * * *