U.S. patent application number 11/264309 was filed with the patent office on 2006-03-23 for process gas introducing mechanism and plasma processing device.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Takayuki Kamaishi, Masato Morishima, Akinori Shimamura.
Application Number | 20060060141 11/264309 |
Document ID | / |
Family ID | 33422096 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060060141 |
Kind Code |
A1 |
Kamaishi; Takayuki ; et
al. |
March 23, 2006 |
Process gas introducing mechanism and plasma processing device
Abstract
A processing gas introducing mechanism for introducing a
processing gas into a processing space is provided between a plasma
generation unit and a chamber of a plasma processing apparatus. The
processing gas introducing mechanism includes a gas introducing
base having therein a gas introducing path for introducing the
processing gas into the processing space, and a near ring-shaped
gas introducing plate equipped in the hole part of the gas
introducing base such that it can be detached therefrom. Herein,
the gas introducing base has a hole part forming one portion of the
processing space in a central portion thereof, and the gas
introducing plate has plural gas discharge holes communicating with
the processing space to discharge thereinto the processing gas from
the gas introducing path.
Inventors: |
Kamaishi; Takayuki;
(Nirasaki-shi, JP) ; Shimamura; Akinori;
(Nirasaki-shi, JP) ; Morishima; Masato;
(Nirasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOKYO ELECTRON LIMITED
Minato-ku
JP
|
Family ID: |
33422096 |
Appl. No.: |
11/264309 |
Filed: |
November 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP04/06165 |
Apr 28, 2004 |
|
|
|
11264309 |
Nov 2, 2005 |
|
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Current U.S.
Class: |
118/715 ;
156/345.33 |
Current CPC
Class: |
H01L 21/67103 20130101;
H01L 21/67069 20130101; H01L 21/67126 20130101; H01J 37/3244
20130101; H01J 37/32449 20130101 |
Class at
Publication: |
118/715 ;
156/345.33 |
International
Class: |
H01L 21/306 20060101
H01L021/306; C23C 16/00 20060101 C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2003 |
JP |
2003-127201 |
Jun 25, 2003 |
JP |
2003-180865 |
Claims
1. A processing gas introducing mechanism, provided between a
plasma generation unit and a chamber accommodating therein a
substrate to be processed of a plasma processing apparatus, for
introducing a processing gas into a processing space formed by the
plasma generation unit and the chamber, comprising: a gas
introducing base disposed on the chamber to support the plasma
generation unit, the gas introducing base having therein a gas
introducing path for introducing the processing gas into the
processing space, and, in a central portion thereof, a hole part
forming one portion of the processing space; and a near ring-shaped
gas introducing plate equipped in the hole part of the gas
introducing base such that it can be detached therefrom, the gas
introducing plate having plural gas discharge holes communicating
with the processing space to discharge thereinto the processing gas
from the gas introducing path.
2. The processing gas introducing mechanism of claim 1, wherein the
plural gas discharge holes are formed in a line along an inner
periphery of the gas introducing plate.
3. The processing gas introducing mechanism of claim 1, wherein the
gas introducing path formed in the gas introducing base has a first
gas flow path into which a processing gas is introduced; an annular
or a semicircular second gas flow path communicating with the first
gas flow path; a number of third gas flow paths extending towards
the processing space from the second gas flow path; and a fourth
gas flow path communicating with the third gas flow paths and the
gas discharge holes formed in the gas introducing plate.
4. The processing gas introducing mechanism of claim 3, wherein the
fourth gas flow path is formed between the gas introducing base and
the gas introducing plate.
5. The processing gas introducing mechanism of claim 1, wherein a
step portion is formed in an inner peripheral portion of the gas
introducing base; another step portion is formed in an outer
peripheral portion of the gas introducing plate; and the gas
introducing plate is attached to the gas introducing base by
matching said two step portions together.
6. The processing gas introducing mechanism of claim 1, wherein the
processing gas introducing mechanism is installed such that it can
be detached from the chamber together with the plasma generation
unit.
7. A plasma processing apparatus, comprising: a plasma generation
unit for producing a plasma; a chamber accommodating therein a
substrate to be processed; and a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber, wherein the processing gas introducing mechanism
includes: a gas introducing base disposed on the chamber to support
the plasma generation unit, the gas introducing base having therein
a gas introducing path for introducing the processing gas into the
processing space, and, in a central portion thereof, a hole part
forming one portion of the processing space; and a near ring-shaped
gas introducing plate equipped in the hole part of the gas
introducing base such that it can be detached therefrom, the gas
introducing plate having plural gas discharge holes communicating
with the processing space to discharge thereinto the processing gas
from the gas introducing path.
8. The plasma processing apparatus of claim 7, wherein the plural
gas discharge holes are formed equi-spacedly along an inner
periphery of the gas introducing plate.
9. The plasma processing apparatus of claim 7, wherein the gas
introducing path formed in the gas introducing base of the
processing gas introducing mechanism has a first gas flow path into
which a processing gas is introduced; an annular or a semicircular
second gas flow path communicating with the first gas flow path; a
number of third gas flow paths extending towards the processing
space from the second gas flow path; and a fourth gas flow path
communicating with the third gas flow paths and the gas discharge
holes formed in the gas introducing plate.
10. The plasma processing apparatus of claim 9, wherein the fourth
gas flow path is formed between the gas introducing base and the
gas introducing plate.
11. The plasma processing apparatus of claim 7, wherein a step
portion is formed in an inner peripheral portion of the gas
introducing base; another step portion is formed in an outer
peripheral portion of the gas introducing plate; and the gas
introducing plate is attached to the gas introducing base by
matching said two step portions together.
12. The plasma processing apparatus of claim 7, further comprising
an attaching and detaching mechanism for attaching the processing
gas introducing mechanism and the plasma generation unit to the
chamber and detaching them therefrom.
13. The plasma processing apparatus of claim 7, wherein the plasma
generation unit has: a dielectric wall; an antenna provided at an
outer side of the dielectric wall; and a high frequency power
supply for supplying a high frequency power to the antenna, wherein
a high frequency power is supplied to the antenna to generate an
inductively coupled plasma in the processing space through the
dielectric wall.
14. The plasma processing apparatus of claim 13, wherein the
dielectric wall is a bell jar, and the antenna is a coil wound in
an outer periphery of the bell jar.
15. A plasma processing apparatus, comprising: a plasma generation
unit for producing a plasma; a chamber accommodating therein a
substrate to be processed; a processing gas introducing mechanism,
provided between the plasma generation unit and the chamber and
disposed in the chamber to support the plasma generation unit, for
introducing a processing gas for producing a plasma into a
processing space formed by the plasma generation unit and the
chamber; and an attaching and detaching mechanism for attaching the
processing gas introducing mechanism and the plasma generation unit
to the chamber and detaching them therefrom.
16. The plasma processing apparatus of claim 15, wherein the
attaching and detaching mechanism includes a hinge mechanism for
rotating as a unit the processing gas introducing mechanism and the
plasma generation unit.
17. The plasma processing apparatus of claim 16, wherein the
attaching and detaching mechanism includes a damper mechanism for
applying a lifting force to the processing gas introducing
mechanism and the plasma generation unit in a rotation direction
thereof when the processing gas introducing mechanism and the
plasma generation unit are rotated as a unit to be detached.
18. The plasma processing apparatus of claim 15, wherein the
attaching and detaching mechanism includes a handle unit for
performing attaching and detaching operations on the processing gas
introducing mechanism and the plasma generation unit.
19. The plasma processing apparatus of claim 15, wherein the plasma
generation unit has: a dielectric wall; an antenna provided at an
outer side of the dielectric wall; and a high frequency power
supply for supplying a high frequency power to the antenna, wherein
a high frequency power is supplied to the antenna to generate an
inductively coupled plasma in the processing space through the
dielectric wall.
20. The plasma processing apparatus of claim 19, wherein the
dielectric wall is a bell jar, and the antenna is a coil wound in
an outer periphery of the bell jar.
21. The plasma processing apparatus of claim 15, wherein the
processing gas introducing mechanism includes: a gas introducing
base disposed on the chamber to support the plasma generation unit,
the gas introducing base having therein a gas introducing path for
introducing the processing gas into the processing space, and, in a
central portion thereof, a hole part forming one portion of the
processing space; and a near ring-shaped gas introducing plate
equipped in the hole part of the gas introducing base such that it
can be detached therefrom, the gas introducing plate having plural
gas discharge holes communicating with the processing space to
discharge thereinto the processing gas from the gas introducing
path.
22. A plasma processing apparatus for performing a plasma
processing on a substrate to be processed, the apparatus
comprising: a chamber accommodating therein the substrate to be
processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; and a mounting table for mounting thereon the
substrate to be processed provided in the chamber, wherein, given
that an inner diameter of the bell jar is D and an inside
measurement of height in a central portion of the bell jar is H, a
flatness K defined by a ratio D/H is in the range of
1.60.about.9.25.
23. The plasma processing apparatus of claim 22, wherein the bell
jar has a cylindrical sidewall portion and a ceiling wall portion
provided thereon, and the antenna is wound in the cylindrical
sidewall portion.
24. The plasma processing apparatus of claim 22, wherein the number
of windings of the antenna is four times or less.
25. The plasma processing apparatus of claim 22, further comprising
a mask, made of a dielectric material, for covering the mounting
table, wherein the mask has a first region where the substrate to
be processed is mounted and a second region around the first
region, and the first and the second region are configured to have
a same height.
26. The plasma processing apparatus of claim 25, wherein, in the
second region, there are provided plural projections for
positioning the substrate to be processed at a position of the
first region.
27. The plasma processing apparatus of claim 25, wherein, in the
first region, there are installed a number of pin holes through
which elevating pins for elevating the substrate to be processed
from the mounting table penetrate; and groove patterns
communicating with the pin holes.
28. The plasma processing apparatus of claim 22, wherein the
processing-gas introducing mechanism includes: a gas introducing
base disposed on the chamber to support the bell jar, the gas
introducing base having therein a gas introducing path for
introducing the processing gas into the processing space, and, in a
central portion thereof, a hole part forming one portion of the
processing space; and a near ring-shaped gas introducing plate
equipped in the hole part of the gas introducing base such that it
can be detached therefrom, the gas introducing plate having plural
gas discharge holes communicated with the processing space to
discharge thereinto the processing gas from the gas introducing
path.
29. The plasma processing apparatus of claim 22, further comprising
an attaching and detaching mechanism for attaching the processing
gas introducing mechanism and the plasma generation unit to the
chamber and detaching them therefrom.
30. The plasma processing apparatus of claim 22, wherein the bell
jar is of a multi-radius domed shape formed of a ceiling wall
portion whose radius R1 is in the range of 1600 mm.about.2200 mm; a
cylindrical sidewall portion; and a corner portion, having a radius
R2 of 20 mm.about.40 mm, for connecting the ceiling wall portion
with the sidewall portion.
31. A plasma processing apparatus for performing a plasma
processing on a substrate to be processed, the apparatus
comprising: a chamber accommodating therein' the substrate to be
processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; and a mounting table for mounting thereon the
substrate to be processed provided in the chamber, wherein, given
that an inner diameter of the bell jar is D and a distance from a
ceiling portion of a central portion of the bell jar to the
mounting table is H1, a flatness K1 defined by a ratio D/H1 is in
the range of 0.90.about.3.85.
32. The plasma processing apparatus of claim 31, wherein the bell
jar has a cylindrical sidewall portion and a ceiling wall portion
provided thereon, and the antenna is wound in-the cylindrical
sidewall portion.
33. The plasma processing apparatus of claim 31, wherein the number
of windings of the antenna is four times or less.
34. The plasma processing apparatus of claim 31, further comprising
a mask, made of a dielectric material, for covering the mounting
table, wherein the mask has a first region where the substrate to
be processed is mounted and a second region around the first
region, and the first and the second region are configured to have
a same height.
35. The plasma processing apparatus of claim 34, wherein, in the
second region, there are provided plural projections for
positioning the substrate to be processed at a position of the
first region.
36. The plasma processing apparatus of claim 34, wherein, in the
first region, there are installed a number of pin holes through
which elevating pins for elevating the substrate to be processed
from the mounting table penetrate; and groove patterns
communicating with the pin holes.
37. The plasma processing apparatus of claim 31, wherein the bell
jar is of a multi-radius domed shape formed of a ceiling wall
portion whose radius R1 is in the range of 1600 mm.about.2200 mm; a
cylindrical sidewall portion; and a corner portion, having a radius
R2 of 20 mm.about.40 mm, for connecting the ceiling wall portion
with the sidewall portion.
38. A plasma processing apparatus for performing a plasma
processing on a substrate to be processed, the apparatus
comprising: a chamber accommodating therein the substrate to be
processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; a mounting table for mounting thereon the substrate to
be processed provided in the chamber; and a mask, made of a
dielectric material, for covering the mounting table and mounting
thereon the substrate to be processed, and wherein the mask has a
first region where the substrate to be processed is mounted and a
second region around the first region, and the first and the second
region are configured to have a same height.
39. The plasma processing apparatus of claim 38, wherein, in the
second region, there are provided plural projections for
positioning the substrate to be processed at a position of the
first region.
40. The plasma processing apparatus of claim 38, wherein, in the
first region, there are installed a number of pin holes through
which elevating pins for elevating the substrate to be processed
from the mounting table penetrate; and groove patterns
communicating with the pin holes.
41. The plasma processing apparatus of claim 38, wherein, given
that an inner diameter of the bell jar is D and an inside
measurement of height in a central portion of the bell jar is H, a
flatness K defined by a ratio D/H is in the range of
1.60.about.9.25.
42. The plasma processing apparatus of claim 38, wherein, given
that an inner diameter of the bell jar is D and a distance from a
ceiling portion of a central portion of the bell jar to the
mounting table is H1, a flatness K1 defined by a ratio D/H1 is in
the range of 0.90.about.3.85.
43. The plasma processing apparatus of claim 38, wherein the bell
jar is of a multi-radius domed shape formed of a ceiling wall
portion whose radius R1 is in the range of 1600 mm.about.2200 mm; a
cylindrical sidewall portion; and a corner portion, having a radius
R2 of 20 mm.about.40 mm, for connecting the ceiling wall portion
with the sidewall portion.
Description
This application is a Continuation Application of PCT International
Application No. PCT/JP04/006165 filed on Apr. 28, 2004, which
designated the United States.
FIELD OF THE INVENTION
[0001] The present invention relates to a processing gas
introducing mechanism for introducing a processing gas for use in a
substrate processing, and a plasma processing apparatus for
performing a plasma processing on a substrate by introducing a
processing gas.
BACKGROUND OF THE INVENTION
[0002] In a semiconductor manufacturing processing, e.g., a Ti film
is formed on a bottom portion of a contact hole formed in a silicon
wafer as an object to be processed; a TiSi is formed by an
interdiffusion between Ti and Si of a substrate; a barrier layer
such as a TiN or the like is formed on the TiSi; an Al layer, a W
layer, a Cu layer and the like are formed on the barrier layer; and
thus, holes are filled and wirings are fabricated. Conventionally,
for performing a series of processings as described above, there
has been employed a metal film forming system of, e.g., a cluster
tool type having plural chambers. In such a metal film forming
system, there is performed, prior to a film forming processing, a
processing for removing a native oxide film, an etching damage
layer and the like, which are formed on the silicon wafer, in order
to obtain a fine contact. As for a device removing such a native
oxide film, it has been known that an inductively coupled plasma is
formed by using a hydrogen gas and an argon gas (Japanese Patent
Laid-open Application No. H04-336426).
[0003] Further, as for a device performing a processing by forming
an inductively coupled plasma, such a configuration has been known
that a bell jar made of a dielectric material is provided at an
upper portion of a chamber in which a semiconductor wafer as an
object to be processed is disposed; and a coil inductor connected
to an RF power supply is wound in an outer periphery of the bell
jar to generate an inductively coupled plasma (Japanese Patent
Laid-open Application No. H10-258227, H10-116826, H11-67746 and
2002-237486).
[0004] This kind of inductively coupled plasma processing
apparatus, a portion of which is shown in FIG. 1, can be configured
such that a plasma generation unit 400 including a bell jar 401, a
coil 403, an RF power supply (not shown) and the like, is fixed to
a chamber 201 accommodating therein an object to be processed by
using a screw through a gas introducing ring 408 for introducing a
processing gas.
[0005] To be specific, the bell jar 401 is fixed at the gas
introducing ring 408 by using a screw component 410 by a bell jar
clamping element 409. At this time, between the bell jar clamping
element 409, the gas introducing ring 408 and the bell jar 401,
there is inserted an annular buffer 409a made of a resin such as
PTFE (polytetrafluoroethylene) or the like, to protect the bell jar
401.
[0006] The gas introducing ring 408 supporting the bell jar 401 is
configured to be supported by a lid base 407, wherein the lid base
407 is mounted on the chamber 201.
[0007] Seal members 413 and 414 such as, e.g., O-ring or the like,
are inserted into spaces formed between the bell jar 401 and the
gas introducing ring 408, and between the lid base 407 and the
chamber 201, to keep an airtightness therebetween.
[0008] For example, a processing gas such as an Ar gas, an H.sub.2
gas or the like is configured to be introduced into a processing
space 402 from a gas channel 408b and a gas hole 408a communicating
with the gas channel 408b. The processing gas introduced as
mentioned above is plasma-excited to perform a plasma processing on
a semiconductor wafer as a substrate to be processed.
[0009] In this case, scattered materials due to the plasma
processing, e.g., a sputter etching, are adhered to a side of the
gas introducing ring 408 or the lid base 407 to thereby become
deposits. If the deposits are getting thicker, they are peeled off
from a place where they have been adhered, to thereby become
foreign materials. As a result, such problems as lowering in an
operation rate of the device, lowering in a production yield of a
semiconductor device and the like, are incurred.
[0010] For this reason, a cover shield 411 is configured to be
attached by using a screw 412, to cover the gas introducing ring
408 and the lid base 407 inside the processing space 402. In case
where the scattered materials due to the etching are adhered to the
cover shield 411, the cover shield 411 is replaced by unscrewing
and then tightly screwing back the screw 412, to thereby prevent
foreign materials from being produced due to accumulation of
deposits.
[0011] Further, a hole portion 411a having a diameter larger than
that of a gas hole 408a is provided in the cover shield 411 in
order not to block a diffusion of the processing gas introduced
from the gas hole 408a. Accordingly, the deposits are likely to be
adhered to the vicinity of the gas hole 408a of the gas introducing
ring 408. Thus, the gas introducing ring 408 as well as the cover
shield 411 needs to be replaced when performing a maintenance.
[0012] However, when replacing the cover shield 411, the bell jar
401, the gas introducing ring 408 and the lid base 407 need to be
detached, thereby increasing the time for maintenance, which
becomes problematic. Further, the gas introducing ring 408 has a
complicated configuration wherein the gas channel 408b and the like
are formed, and cost of a component to be replaced is expensive,
thereby increasing the running-cost of the device and lowering a
productivity of the semiconductor device.
[0013] Meanwhile, in such an inductively coupled plasma processing
apparatus, a shape of the processing space applied for the plasma
processing has not been studied in detail and the uniformity in the
plasma processing is not necessarily satisfactory.
[0014] Further, as for a configuration of a susceptor mounting
thereon a wafer inside a vessel, in which a plasma is generated, it
has been widely known that an area for supporting the wafer is cut
to have a recess portion to perform a positioning of the wafer
(Japanese Patent Laid-open Application No. 2002-151412).
[0015] However, even in case of adopting such a configuration of
the susceptor, the uniformity in the plasma processing is not
satisfactory.
SUMMARY OF THE INVENTION
[0016] It is, therefore, a primary object of the present invention
to provide a processing gas introducing mechanism and a plasma
processing apparatus capable of reducing running-cost by cutting
cost of components to be replaced when performing a
maintenance.
[0017] It is another object of the present invention to provide a
plasma processing apparatus capable of easily performing a
maintenance and reducing the time therefor.
[0018] It is still another object of the present invention to
provide a plasma processing apparatus capable of improving the
in-surface uniformity of an object to be processed in a plasma
processing by using an inductively coupled plasma.
[0019] It is still another object of the present invention to
provide a plasma processing apparatus capable of improving the
in-surface uniformity of an object to be processed, without
increasing cost for design or fabrication, and without losing the
universality of a configuration of a device.
[0020] In accordance with the first aspect of the present
invention, there is provided a processing gas introducing
mechanism, provided between a plasma generation unit and a chamber
accommodating therein a substrate to be processed of a plasma
processing apparatus, for introducing a processing gas into a
processing space formed by the plasma generation unit and the
chamber, including: a gas introducing base disposed on the chamber
to support the plasma generation unit, the gas introducing base
having therein a gas introducing path for introducing the
processing gas into the processing space, and, in a central portion
thereof, a hole part forming one portion of the processing space;
and a near ring-shaped gas introducing plate equipped in the hole
part of the gas introducing base such that it can be detached
therefrom, the gas introducing plate having plural gas discharge
holes communicating with the processing space to discharge
thereinto the processing gas from the gas introducing path.
[0021] In accordance with the second aspect of the present
invention, there is provided a plasma processing apparatus,
including: a plasma generation unit for producing a plasma; a
chamber accommodating therein a substrate to be processed; and a
processing gas introducing mechanism, provided between the plasma
generation unit and the chamber, for introducing a processing gas
for producing a plasma into a processing space formed by the plasma
generation unit and the chamber, wherein the processing gas
introducing mechanism contains: a gas introducing base disposed on
the chamber to support the plasma generation unit, the gas
introducing base having therein a gas introducing path for
introducing the processing gas into the processing space, and, in a
central portion thereof, a hole part forming one portion of the
processing space; and a near ring-shaped gas introducing plate
equipped in the hole part of the gas introducing base such that it
can be detached therefrom, the gas introducing plate having plural
gas discharge holes communicating with the processing space to
discharge thereinto the processing gas from the gas introducing
path.
[0022] In accordance with the third aspect of the present
invention, there is provided a plasma processing apparatus,
including: a plasma generation unit for producing a plasma; a
chamber accommodating therein a substrate to be processed; a
processing gas introducing mechanism, provided between the plasma
generation unit and the chamber and disposed in the chamber to
support the plasma generation unit, for introducing a processing
gas for producing a plasma into a processing space formed by the
plasma generation unit and the chamber; and an attaching and
detaching mechanism for attaching the processing gas introducing
mechanism and the plasma generation unit to the chamber and
detaching them therefrom.
[0023] In accordance with the first and the second aspect of the
present invention, the gas introducing base is configured to be
disposed on the chamber to support the plasma generation unit, to
have therein the gas introducing path for introducing the
processing gas into the processing space, and, in a central portion
thereof, and to have the hole part forming one portion of the
processing space; and the near ring-shaped gas introducing plate
having plural gas discharge holes communicating with the processing
space to discharge thereinto the processing gas from the gas
introducing path is equipped in the hole part of the gas
introducing base such that it can be detached therefrom. Thus, the
configuration of the processing gas introducing mechanism becomes
simplified, and consumables thereof may be replaced easily.
Accordingly, the time for maintenance may be shortened, and an
operating rate of the plasma processing apparatus is increased to
thereby improve the productivity thereof. Further, since the
configuration of the processing gas introducing mechanism becomes
simplified, the production cost thereof may be reduced, and thus,
cost reduction in the configuration of the plasma processing
apparatus may be achieved.
[0024] In accordance with the third aspect of the present
invention, the attaching and detaching mechanism for attaching the
processing gas introducing mechanism and the plasma generation unit
to the chamber and detaching them therefrom is installed, so that
the maintenance may be readily performed and the time therefor may
be shortened.
[0025] In accordance with the fourth aspect of the present
invention, there is provided a plasma processing apparatus for
performing a plasma processing on a substrate to be processed, the
apparatus including: a chamber accommodating therein the substrate
to be processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; and a mounting table for mounting thereon the
substrate to be processed: provided in the chamber, wherein, given
that an inner diameter of the bell jar is D and an inside
measurement of height in a central portion of the bell jar is H, a
flatness K defined by a ratio D/H is in the range of
1.60.about.9.25.
[0026] In accordance with the fifth aspect of the present
invention, there is provided a plasma processing apparatus for
performing a plasma processing on a substrate to be processed, the
apparatus including: a chamber accommodating therein the substrate
to be processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; and a mounting table for mounting thereon the
substrate to be processed provided in the chamber, wherein, given
that an inner diameter of the bell jar is D and a distance from a
ceiling portion of a central portion of the bell jar to the
mounting table is H1, a flatness K1 defined by a ratio D/H1 is in
the range of 0.90.about.3.85.
[0027] The fourth and the fifth aspect of the present invention are
based on the knowledge found by the present inventors that the
height of the bell jar has a significant impact on a variation in
the density distribution of the plasma for the substrate to be
processed in the processing apparatus using the inductively coupled
plasma as mentioned above, and it is effective to optimize the
height of the bell jar to improve the in-surface uniformity in the
plasma processing as described above on the silicon wafer of the
large diameter, particularly.
[0028] In accordance with the fourth aspect of the present
invention, since the flatness K of the bell jar in which a plasma
is produced is set large in the range of 1.60.about.9.25, the
plasma produced in the bell jar above the substrate to be processed
disposed on the mounting table gets wider towards a process surface
of the substrate to be processed, and thus, the density
distribution of the plasma becomes uniform along the process
surface. Accordingly, the in-surface uniformity of the substrate to
be processed in the plasma processing is improved.
[0029] In accordance with the fifth aspect of the present
invention, since the flatness K1 of the bell jar, taking the
distance from the mounting table to the ceiling portion of the bell
jar into consideration, is set large in the range of
0.90.about.3.85, the plasma produced in the bell jar above the
substrate to be processed disposed on the mounting table gets wider
towards a process surface of the substrate to be processed, and
thus, the density distribution of the plasma becomes uniform along
the process surface. Accordingly, the in-surface uniformity of the
substrate to be processed in the plasma processing is improved.
[0030] Further, in the fourth and the fifth aspect, the bell jar is
made flatter while employing the configurations of the conventional
art for other chamber parts, so that it is possible to improve the
in-surface uniformity of the substrate to be processed during the
plasma processing without bring about running-cost increase due to
modification of design for the chamber part or the like, or
lowering of the universality, which is caused by modification of
external connecting configuration of the chamber part or the
like.
[0031] In accordance with the sixth aspect of the present
invention, there is provided a plasma processing apparatus for
performing a plasma processing on a substrate to be processed, the
apparatus including: a chamber accommodating therein the substrate
to be processed; a plasma generation unit, having a bell jar and an
antenna, for producing a plasma inside the bell jar, wherein the
bell jar made of a dielectric material is provided at an upper part
of the chamber to communicate therewith and the antenna is coiled
around an outer side of the bell jar to generate an induced
electric field in the bell jar; a processing gas introducing
mechanism, provided between the plasma generation unit and the
chamber, for introducing a processing gas for producing a plasma
into a processing space formed by the plasma generation unit and
the chamber; a mounting table for mounting thereon the substrate to
be processed provided in the chamber; and a mask, made of a
dielectric material, for covering the mounting table and mounting
thereon the substrate to be processed, and wherein the mask has a
first region where the substrate to be processed is mounted and a
second region around the first region, and the first and the second
region are configured to have a same height.
[0032] The sixth aspect of the present invention is to resolve such
a problem that, in the conventional susceptor, an area for
supporting the wafer is cut to have a recess portion and an
impedance in the outer periphery of the recess portion gets larger
than that of the central portion thereof, so that a bias for
producing a plasma and the like may be affected, and thus, lowering
the in-surface uniformity in the plasma processing. Further, in the
mask of the mounting table where the substrate to be processed is
mounted, since the first region where the substrate to be processed
is mounted and the second region around the first region are
configured to have a same height, impedances in the first and the
second region are uniform during the plasma generation, and density
distributions of the plasma in the peripheral and the central
portions of the substrate to be processed are uniform, to thereby
improve the in-surface uniformity of the substrate to be processed
during the plasma processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The above and other objects and features of the present
invention will become apparent from the following description of
preferred embodiments given in conjunction with the accompanying
drawings, in which:
[0034] FIG. 1 offers a view schematically showing a magnified
portion of a conventional plasma processing apparatus;
[0035] FIG. 2 shows a cross sectional view schematically showing a
plasma processing apparatus in accordance with a first embodiment
of the present invention;
[0036] FIG. 3 explains a cross sectional view showing a magnified
gas introducing mechanism of the plasma processing apparatus in
accordance with the first embodiment of the present invention;
[0037] FIG. 4A sets forth a perspective view showing a gas
introducing base forming the gas introducing mechanism;
[0038] FIG. 4B presents a cross sectional view showing the gas
introducing base;
[0039] FIG. 5A provides a perspective view showing a gas
introducing plate forming the gas introducing mechanism;
[0040] FIG. 5B describes a cross sectional view showing the gas
introducing plate;
[0041] FIG. 6 depicts a cross sectional view showing a magnified
portion of the gas introducing mechanism;
[0042] FIG. 7 describes a cross sectional view showing a modified
example of the gas introducing mechanism;
[0043] FIG. 8 offers a perspective view showing an external
appearance of the plasma processing apparatus in accordance with
the first embodiment of the present invention;
[0044] FIG. 9 shows a cross sectional view showing a plasma
processing apparatus in accordance with a second embodiment of the
present invention;
[0045] FIG. 10A is a view showing a simulation result of a density
distribution of Ar.sup.+ in Ar plasma of the conventional plasma
processing apparatus;
[0046] FIG. 10B provides a view showing a simulation result of a
density distribution of Ar.sup.+ in plasma for the plasma
processing apparatus in accordance with the second embodiment of
the present invention;
[0047] FIG. 11 presents a graph showing an exemplary effect of a
shape of a bell jar for the plasma processing apparatus in
accordance with the second embodiment of the present invention;
[0048] FIG. 12 sets forth a cross sectional view showing a modified
example of the plasma processing apparatus in accordance with the
second embodiment of the present invention;
[0049] FIG. 13 describes a schematic cross sectional view showing a
mounting configuration of the semiconductor wafer for a plasma
processing apparatus in accordance with a third embodiment of the
present invention;
[0050] FIG. 14 offers a cross sectional view showing a magnified
mounting configuration of the semiconductor wafer of FIG. 13;
[0051] FIG. 15 is a plane view showing the mounting configuration
of the semiconductor wafer of FIG. 13; and
[0052] FIG. 16 presents a graph showing a relationship between a
variation in an etching result and a step height of a mounting
portion of the semiconductor wafer in accordance with the third
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0053] Preferred embodiments of the present invention will be
described with reference to the accompanying drawings.
First Embodiment
[0054] FIG. 2 is a schematic configuration of a plasma processing
apparatus in accordance with a first embodiment of the present
invention. A plasma processing apparatus 100 for performing a
plasma processing on a substrate to be processed is employed, e.g.,
in a processing for plasma-etching to remove an impurity layer
containing an oxide film such as a native oxide or the like, which
is formed on a metal film or a silicon formed on the substrate to
be processed.
[0055] The plasma processing apparatus 100 includes a chamber 10
accommodating therein a semiconductor wafer as a substrate to be
processed; a wafer supporting portion 20 supporting the
semiconductor wafer in the chamber 10; a plasma generation unit 40,
installed to cover the chamber 10, for generating a plasma in a
processing space S where a plasma processing is performed on the
wafer; a gas introducing mechanism 50 for introducing a gas for
producing a plasma into the processing space S; and a gas supply
unit 60 for supplying a gas for producing a plasma into the gas
introducing mechanism 50. Further, though not shown in FIG. 2,
there is also included an attaching and detaching mechanism, as
explained below, for attaching and detaching the gas introducing
mechanism 50 and the plasma generation unit 40.
[0056] The chamber 10 made of a metal material, such as aluminum,
aluminum alloy or the like, has a cylindrical main body 11; and an
exhaust chamber 12 provided at a lower part of the main body 11 and
having a diameter smaller than that of the main body 11. The
exhaust chamber 12 is installed to uniformly exhaust an inside of
the main body 11.
[0057] At an upper part of the chamber 10, there is installed a
bell jar 41 as a constituent of the plasma generation unit 40 in
such a way that it is connected to the chamber 10 to be able to
communicate therewith. The bell jar 41 made of a dielectric
material is of a cylindrical shape, e.g., a domed shape, whose
upper portion is closed. Further, a processing vessel is formed by
the chamber 10 and the bell jar.41, and an inside thereof
corresponds to the processing space S.
[0058] The wafer supporting portion 20 has a susceptor (mounting
table) 21, made of a dielectric material, for horizontally
supporting the semiconductor wafer W as an object to be processed,
wherein the susceptor 21 is disposed to be supported by a
cylindrical supporting member 22 made of a dielectric material.
Further, it can be configured such that a recess portion having a
substantially same shape as that of the wafer W is formed at a top
surface of the susceptor 21 to accommodate therein the wafer W, or
an electrostatic adsorption mechanism may be provided at the top
surface of the susceptor 21 to allow the wafer W to be adsorbed. As
for the dielectric material forming the susceptor 21, ceramic
materials, e.g., AlN and Al.sub.2O.sub.3, may be enumerated, and,
among these, AlN of a high thermal conductivity is preferably
used.
[0059] At an outer periphery of the susceptor 21, there is
installed a vertically movable shadow ring 23 to cover an edge of
the wafer W mounted on the susceptor 21. The shadow ring 23 focuses
a plasma to facilitate to make it uniform. Further, it functions to
protect the susceptor 21 from the plasma.
[0060] A mesh-shaped electrode 24 made of a metal, such as Mo, W or
the like, is horizontally buried into the susceptor 21 at the upper
portion thereof. To the electrode 24, there is connected a high
frequency power supply 25 for attracting ions by applying a high
frequency bias to the wafer, through a matching unit 26.
[0061] Further, a heater 28 is buried into the susceptor 21 to be
disposed below the electrode 24 and can heat the wafer W to keep it
at a predetermined temperature by feeding a power to the heater 28
from a heater source 29. Still further, feeder lines extending to
the electrode 24 and the heater 28 are inserted into the supporting
member 22.
[0062] Three wafer elevating pins 31 (only two of them are shown)
for supporting and lifting up and down the wafer W are inserted
into the susceptor 21; and they are installed such that they can be
popped out from or popped into the top surface of the susceptor 21.
These wafer elevating pins 31 are fixed at a supporting plate 32
and elevated through the supporting plate 32 by using an elevation
mechanism 33 such as an air cylinder or the like.
[0063] Inside the main body 11 of the chamber 10, there is
installed attachably and detachably a near cylindrical chamber
shield 34 for preventing by-products and the like, which are
produced during the plasma etching, from being adhered to an inner
wall of the main body 11 along therewith. The chamber shield 34 is
made of a Ti material (Ti or Ti alloy). As for a shield material,
an Al material may be used, but particles may be generated during
the processing in case of using it. Therefore, a Ti material is
preferably used, since it has a high adhesivity to deposits and is
able to significantly reduce generation of particles. Further, a
shield main body of the Al material coated with Ti may be used.
Still further, in a surface of the chamber shield 34, there may be
formed fine prominences and depressions by using a blast processing
or the like to improve the adhesivity to the deposits. The chamber
shield 34 is fixed at a bottom wall of the main body 11 of the
chamber 10 by using bolts 35 in some places (two places in the
drawing); and it is detached from the main body 11 of the chamber
10 by pulling out the bolts 35. Accordingly, a maintenance of the
chamber 10 may be readily performed.
[0064] At a sidewall of the chamber 10, there is formed an opening
36, which is opened or closed by using a gate valve 37. While the
gate valve 37 is opened, the semiconductor wafer W is transferred
between a neighboring load-lock chamber (not shown) and the chamber
10.
[0065] The exhaust chamber 12 of the chamber 10 is provided to be
downwardly protruded to cover a circular hole formed in the center
of the bottom wall of the main body 11. A gas exhaust line 38 is
connected to a side of the exhaust chamber 12, and a gas exhaust
unit 39 is connected thereto. Further, by operating the gas exhaust
unit 39, insides of the chamber 10 and the bell jar 41 can be
uniformly depressurized to a predetermined vacuum level.
[0066] The plasma generation unit 40 has the aforementioned bell
jar 41; a coil 43 as an antenna unit, which is wound in an outer
side of the bell jar 41; a high frequency power supply 44 supplying
a high frequency power to the coil 43; and a shield vessel 46
covering the bell jar 41 and the coil 43 to shield ultraviolet and
electromagnetic waves of plasma.
[0067] The bell jar 41 made of a dielectric material such as
ceramic material, e.g., quartz, AlN or the like, has a cylindrical
sidewall portion 41a and a domed ceiling wall portion 41b disposed
thereon. The coil 43 is wound by the predetermined number of
windings in a substantially horizontal direction in the outer side
of the side wall portion 41a forming a cylinder of the bell jar 41,
with 5 10 mm pitch between coils, and preferably, 8 mm pitch. The
coil 43 is supported and fixed by using an insulating material,
e.g., a fluorine resin or the like. In the drawing, the number of
windings of the coil 43 is seven times.
[0068] The high frequency power supply 44 is connected to the coil
43 through a matching unit 45.
[0069] The high frequency power supply 44 generates a high
frequency power of a frequency, e.g., 300 kHz 60 MHz, and
preferably, 450 kHz.about.13.56 MHz. By supplying a high frequency
power to the coil 43 from the high frequency power supply 44, an
inductive electromagnetic field is generated in the processing
space S inside the bell jar 41 through the side wall portion 41a
thereof, which is made of a dielectric material.
[0070] The gas introducing mechanism 50 is provided between the
chamber 10 and the bell jar 41, for supporting the bell jar 41, and
includes a gas introducing base 48 mounted on the chamber 10; a gas
introducing plate 49 equipped inside the gas introducing base 48;
and a bell jar clamping element 47 for fixing the bell jar 41 to
the gas introducing base 48. Further, it is configured such that a
processing gas from the gas supply mechanism 60 is to be discharged
to the processing space S through a gas introducing path 48e formed
in the gas introducing base 48 and gas discharge openings 49a
formed in the gas introducing plate 49 that will be explained
later.
[0071] The gas supply mechanism 60 has an Ar gas supply source 61
and an H.sub.2 gas supply source 62, to which gas lines 63 and 64
are connected, respectively, wherein the gas lines 63 and 64 are
connected to a gas line 65. Further, the gases are guided to the
gas introducing mechanism 50 through the gas line 65. In the gas
lines 63 and 64, there are installed mass flow controllers 66, and
opening/closing valves 67 having therebetween the mass flow
controllers 66.
[0072] The Ar gas and the H.sub.2 gas as a processing gas, which
have been supplied to the gas introducing mechanism 50 through the
gas line 65 of the gas supply mechanism 60, as mentioned above, are
discharged to the processing space S through the gas introducing
path 48e of the gas introducing mechanism 50 and the gas discharge
holes 49a formed in the gas introducing plate 49; and they turn
into a plasma by the inductive electromagnetic field generated in
the processing space S as described above, to thereby form an
inductively coupled plasma.
[0073] In the following, a configuration of the gas introducing
mechanism 50 will be explained in detail.
[0074] As in a magnified view shown in FIG. 3, at the gas
introducing base 48, there is formed a first gas flow path 48a
coupled to a gas introducing path 11b formed at a wall portion of
the main body 11 of the chamber 10, wherein the first gas flow path
48a is coupled to a second gas flow path 48b formed in a
substantially annular or semicircular shape inside the gas
introducing base 48. Further, plural third gas flow paths 48c are
formed equi-spacedly or diagonally toward the inner side from the
second gas flow path 48b. Meanwhile, a near annular fourth gas flow
path 48d is formed between the gas introducing base 48 and the gas
introducing plate 49 such that the gas can be diffused uniformly,
and the third gas flow paths 48c are connected thereto. Further,
these first through fourth gas flow paths 48a, 48b, 48c and 48d are
configured to communicate with each other to form a gas introducing
path 48e.
[0075] The processing gas introduced from the gas line 65 is
diffused uniformly in the second gas flow path 48b formed in a
substantially annular or semicircular shape from the first gas flow
path 48a formed at the gas introducing base 48, through the gas
introducing path 11b. Further, the processing gas reaches the
fourth gas flow path 48d of a substantially annular shape through
the plural third gas flow paths 48c, which communicate with the
second gas flow path 48b to be extended towards the processing
space S.
[0076] Meanwhile, as mentioned above, in the gas introducing plate
49, there are equi-spacedly formed a number of gas discharge holes
49a communicating with the fourth gas flow path 48d and the
processing space S; and the processing gas is discharged to the
processing space S through the gas discharge holes 49a from the
fourth gas flow path 48d. Further, in the vicinity of a connection
part of the gas introducing path 11b and the first gas flow path
48a, there are installed seal rings 52 to keep an airtightness of a
path, through which the processing gas is supplied.
[0077] Further, the gas introducing base 48 is configured to be
mounted on the main body 11 of the chamber 10 while supporting the
bell jar 41, as described above. At this time, between the gas
introducing base 48 and the bell jar 41, and between the gas
introducing base 48 and the, main body 11 of the chamber 10, there
are intervened respective seal members 53 and 54, e.g., O-ring or
the like, to keep an airtightness of the processing space S.
[0078] The bell jar 41 is supported by the gas introducing base 48,
and an end portion thereof is fixed thereto by using the bell jar
clamping element 47. Further, the bell jar clamping element 47 is
clamped by using a screw 55 on the gas introducing base 48. Between
the bell jar clamping element 47 and the gas introducing base 48
and the bell jar 41, there is intervened with a buffer 47a made of
PTFE or the like. It is intended to prevent the bell jar 41 made of
a dielectric material, e.g., quartz, A.sub.2O.sub.3, AlN or the
like, from being damaged due to collision with the bell jar
clamping element 47 or the gas introducing base 48 made of a metal
material, e.g., Al or the like. Further, the gas introducing base
48 and the gas introducing plate 49 are clamped with each other by
using screws 56.
[0079] In the following, the gas introducing base 48 and the gas
introducing plate 49 forming the aforementioned processing gas
introducing mechanism 50 will be discussed in detail.
[0080] FIGS. 4A and 4B present the gas introducing base 48: wherein
FIG. 4A is a perspective view thereof; and FIG. 4B is a cross
sectional view taken along A-A line of FIG. 4A. The gas introducing
base 48 made of a metal material, e.g., Al or the like, is
configured to have a substantially circular hole 48f in the center
thereof, as shown in FIG. 4A, wherein the hole 48f forms one
portion of the processing space S when the gas introducing base 48
is attached to the plasma processing apparatus 100. In the gas
introducing base 48, as shown in the cross section of FIG. 4B,
there are formed the above-described first through third gas flow
paths 48a, 48b and 48c; and the third gas flow paths 48c
communicate with a space 48d'. In an inner peripheral surface of
the gas introducing base 48, there is formed a step portion, which
matches that of the gas introducing plate 49. Further, when the gas
introducing plate 49 is attached to the gas introducing base 48, a
fourth gas flow path 48d is formed in a part corresponding to the
space 48d'.
[0081] FIGS. 5A and 5B present the gas introducing plate 49:
wherein FIG. 5A is a perspective view thereof; and FIG. 5B is a
cross sectional view taken along B-B line of FIG. 5A.
[0082] The gas introducing plate 49 of a substantially circular
shape is made of a metal material, e.g., Ti, Al or the like, or a
coated material wherein an Al basic material is coated with Ti by
using a spraying or the like. The gas introducing plate 49 has a
cylindrical main body 49b having a step portion, and a flange part
49c formed at an outer peripheral portion of a bottom portion
thereof; and a number of gas discharge holes 49a are provided along
a circumferential surface of the main body 49b. Further, in the
flange part 49c, there are formed plural fixing holes, into which
the aforementioned screws 56 are inserted to fix the flange part
49c to the gas introducing base 48.
[0083] FIG. 6 describes a state in which the gas introducing base
48 is matched with the gas introducing plate 49 to be fixed thereto
by using the screws 56. As shown in this drawing, the gas
introducing base 48 is fixed together with the gas introducing
plate 49 by using the screws 56 in the state in which the step
portion of the gas introducing base 48 is coincided with that of
the gas introducing plate 49 to be matched thereto. Further, at
this time, the fourth gas flow path 48d is formed therebetween, so
that the gas is discharged from the gas discharge holes 49a
communicating with the fourth gas flow path 48d. The gas
introducing plate 49 is configured to be easily attached to the gas
introducing base 48 or detached therefrom by using the screws
56.
[0084] As described in FIG. 7, a gas discharge hole 49a' may be of,
e.g., a cone or a trumpet shape whose width gets wider towards the
processing space S from the fourth gas flow path 48d. In this way,
the processing gas can be supplied efficiently and uniformly into
the large processing space S.
[0085] In the following, attaching and detaching mechanisms of the
aforementioned gas introducing mechanism 50 and the plasma
generation unit 40 will now be explained with reference to FIG. 8
showing an external appearance of the plasma processing apparatus
100.
[0086] As described in FIG. 8, the attaching and detaching
mechanism 70 has a pair of first hinge components 72 equipped by
using the screws 72c at one side of the gas introducing plate 48,
which defines an outer periphery of the gas introducing mechanism
50; and a second hinge component 73 provided between the pair of
first hinge components 72 and fixed to the main body 11 of the
chamber 10 by using the screws 73c. In the central portions of the
hinge components 72 and 73, there are provided respective bearing
72a and 73a, through which a shaft 71 is inserted. In this way, the
gas introducing mechanism 50 and the plasma generation unit 40 are
upwardly rotated to be detached from the chamber 10 by using the
shaft 71 as a center of rotation, from the state where the gas
introducing mechanism 50 having a rectangular external appearance
is attached to the main body 11 of the chamber 10, wherein the main
body 11 is of an identical rectangular shape. Namely, the gas
introducing mechanism 50 and the plasma generation unit 40 are
configured to be readily attached to the chamber 10 and detached
therefrom by the attaching and detaching mechanism 70, so that a
maintenance can be readily performed while the gas introducing
mechanism 50 and the plasma generation unit 40 are upwardly
rotated.
[0087] Further, the attaching and detaching mechanism 70 has a
damper 75. One end of the damper 75 is fixed to the gas introducing
plate 48 by using a fixing member 75a, and the other end thereof is
fixed to the main body 11 of the chamber 10.
[0088] The damper 75 having therein, e.g., Hydraulic equipment, is
configured to be extensible and contractible, and to apply a
lifting force along a height direction, i.e., a rotation direction,
when the gas introducing mechanism 50 and the plasma generation
unit 40 are upwardly rotated. For the same reason, it is possible
to reduce the force required for supporting the gas introducing
mechanism 50 and the plasma generation unit 40, when they are
rotated upward. Further, a handle 74 is provided at the gas
introducing base 48 by using screws 74a to be gripped by the
operator, when the plasma generation unit 40 being attached or
detached.
[0089] In the following, a processing operation by using the plasma
processing apparatus 100 as configured above will be discussed.
[0090] First, the gate valve 37 is opened to load the wafer W into
the chamber 10 by using a transfer arm (not shown), and the wafer
elevating pins 31 protruded from the susceptor 21 receive thereon
the wafer W. Subsequently, the wafer elevating pins 31 are lowered
to allow the wafer W to be mounted on the top surface of the
susceptor 21; and the shadow rings 23 are lowered.
[0091] Thereafter, the gate valve 37 is closed to exhaust insides
of the chamber 10 and the bell jar 41 by using the gas exhaust unit
39 to keep them at a predetermined depressurized state. In such a
depressurized state, the Ar gas and the H.sub.2 gas supplied from
the gas supply mechanism 60 are discharged to the processing space
S through the gas introducing mechanism 50. At the same time, high
frequency powers are supplied to the electrode 24 inside the
susceptor 21 and the coil 43 from the high frequency power supplies
25 and 44, respectively, so that an electric field is generated in
the processing space S and the gas introduced into the bell jar 41
is excited to ignite the plasma.
[0092] After the ignition of the plasma, an induced current flows
through the bell jar 41 to generate the plasma continuously, and a
native oxide film formed on the wafer W, e.g., a silicon oxide
formed on a silicon or a metal oxide film formed on a metal film,
is etched to be removed by the plasma. At this time, a bias is
applied to the susceptor 21 from the high frequency power supply
25, and the wafer W is kept at a predetermined temperature by the
heater 28.
[0093] The conditions may be set such that a pressure of the
processing space S is 0.1.about.13.3 Pa, and preferably,
0.1.about.2.7 Pa; a temperature of the wafer is
100.about.500.degree. C.; a flow, rate of Ar gas is
0.001.about.0.03 mL/min and that of H.sub.2 is 0.about.0.06 L/min,
and preferably, 0.about.0.03 L/min; a frequency of the high
frequency power supply 44 for producing a plasma is 300
kHz.about.60 MHz, and preferably, 450 kHz.about.13.56 MHz; and a
power is 500.about.3000 W, and a power of the high frequency power
supply 25 is 0.about.1000 W (-20.about.-200 V as a bias potential).
At this time, a plasma density is 0.7.about.10.times.10.sup.10
atoms/cm.sup.3, and preferably, 1.about.6.times.10.sup.10
atoms/cm.sup.3. Under such conditions, the processing is performed
for about 30 seconds, so that, e.g., a silicon oxide film
(SiO.sub.2) is removed by about 10 nm.
[0094] As mentioned above, by removing an impurity layer containing
oxides such as a native oxide film and the like, it is possible to
achieve such effects that adhesivity of a film to be formed is
improved and an electrical resistance value is reduced.
[0095] In this case, the gas introducing mechanism 50 for
discharging the processing gas also functions to introduce the
processing gas into the processing space S by being mounted on the
main body 11 of the chamber 10 while keeping an airtightness, as
well as to support the bell jar 41, as described above. Therefore,
the number of components in the plasma processing apparatus is
reduced to simplify the configuration, so that cost reduction in
the plasma processing apparatus may be achieved.
[0096] Further, in case when performing the sputter etching as the
plasma processing on the semiconductor wafer W as mentioned, if
scattered materials are deposited to members around the
semiconductor wafer W due to the sputtering, particulates such as
fine particles may be generated to thereby lower the production
yield of the semiconductor device. For example, the scattered
materials are likely to be deposited to the members around the
semiconductor wafer W, specifically, the part where deposits are
accumulated, e.g., around the gas discharge holes 49a.
[0097] Therefore, in the present embodiment, the gas introducing
plate 49 is configured to be attached to the gas introducing base
48 by using the screws 56 and detached therefrom. Accordingly, the
gas introducing plate 49 may be readily replaced, and the time for
maintenance may be shortened. Further, since the gas introducing
plate 49 has a simple configuration and is formed of cheap
components, the cost for maintenance may be kept low.
[0098] Further, as described above, the gas introducing mechanism
50 and the plasma generation unit 40 can be readily attached and
detached by the attaching and detaching mechanism 70. Therefore, in
case when the plasma processings are repeatedly performed, and
thus, maintenance needs to be performed, the time for maintenance
of the plasma processing apparatus 100 may be shortened and an
operation rate thereof can be improved. Further, productivity of
the semiconductor device may be improved.
[0099] To be specific, in case where the maintenance is performed
on the chamber 10 when replacing the bell jar 41 or an operation
such as wet-cleaning or the like is performed, the plasma
generation unit 40 needs to be detached therefrom. At this time,
the plasma generation unit 40 and the gas introducing mechanism 50
may be simultaneously rotated to be detached together, as mentioned
above, and the maintenance operation therefor may be performed in a
short time.
[0100] Further, since the gas introducing mechanism 50 and the
plasma generation unit 40 can be readily attached and detached as
mentioned above, an operation for replacing the gas introducing
plate 49 of the gas introducing mechanism may be performed readily
in a short time by detaching the gas introducing mechanism 50 and
the plasma generation unit 40 from the chamber 10.
[0101] Still further, the attaching and detaching mechanism 70 has
the damper 75 exerting the lifting force to the plasma generation
unit 40 in its opening direction, so that it is possible to reduce
the force required for supporting the plasma generation unit 40
when it being rotated. Therefore, the maintenance operation gets
easier, and efficiency thereof is improved.
Second Embodiment
[0102] In the following, a second embodiment of the present
invention will be discussed.
[0103] FIG. 9 is a schematic view of a configuration of a plasma
processing apparatus in accordance with the second embodiment of
the present invention. The plasma processing apparatus 100', like
as the plasma processing apparatus 100 of the first embodiment, is
applied to a process for plasma-etching to remove an impurity layer
containing an oxide film, e.g., a native oxide film or the like,
formed on a metal film or a silicon formed on a substrate to be
processed. Further, the plasma processing apparatus 100' has a
chamber 10' accommodating therein a semiconductor wafer as a
substrate to be processed; a wafer supporting portion 20'
supporting the semiconductor wafer inside the chamber 10'; a plasma
generation unit 40', installed to cover the chamber 10', for
producing a plasma in a processing space S where a plasma
processing is performed on a wafer; a gas introducing mechanism 50'
introducing into the processing space S a gas for producing a
plasma; and a gas supply mechanism 60' supplying the gas for
producing a plasma to the gas introducing mechanism 50'.
[0104] Among these, since the chamber 10', the wafer supporting
portion 20' and neighboring members thereof are configured to be
completely identical to those of the first embodiment, identical
reference numerals will be used for the corresponding parts having
substantially same functions and configurations of FIG. 2, and
explanations thereof will be omitted.
[0105] The plasma generation unit 40' has a bell jar 141; a coil
143 as an antenna member, which is wound in an outer side of the
bell jar 141; a high frequency power supply 144 supplying a high
frequency power to the coil 143; and a conductive member 147 as a
facing electrode provided on a ceiling wall of the bell jar
141.
[0106] The bell jar 141 made of a dielectric material such as a
ceramic material, e.g., quartz, A.sub.2O.sub.3, AlN or the like, is
of a multi-radius domed shape, which has a cylindrical side wall
portion 141a; a domed ceiling wall portion 141b (radius R1=1600
mm.about.2200 mm) formed thereon; and a curved corner portion 141c
(radius R2=20 mm.about.40 mm) connecting the side wall portion 141a
with the ceiling wall portion 141b. At an outer side of the side
wall portion 141a forming a cylinder of the bell jar 141, the coil
143 is wound with a predetermined number of windings in the
substantially horizontal direction at 5.about.10 mm pitch between
coils, and preferably, 8 mm pitch; and it is supported to be fixed
by using an insulating material, e.g., a fluorine resin or the
like. In the drawing, the number of windings of the coil 143 is
four times. The high frequency power supply 144 is connected to the
coil 143 through a matching unit 145. The high frequency power
supply 144 has a frequency in the range of 300 kHz.about.60 MHz,
and preferably, 450 kHz.about.13.56 MHz. Further, a high frequency
power is supplied from the high frequency power supply 144 to the
coil 143 to generate an inductive electromagnetic field in the
processing space S inside the bell jar 141 through the side wall
portion 141a thereof, which is made of a dielectric material.
[0107] The gas introducing mechanism 50' has a ring-shaped gas
introducing member 130 provided between the chamber 10' and the
bell jar 141. The gas introducing member 130 made of a conductive
material such as Al or the like is grounded. A number of gas
discharge holes 131 are formed in the gas introducing member 130
along the inner peripheral surface thereof. Further, inside the gas
introducing member 130, there is provided an annular gas flow path
132, into which an Ar gas, an H.sub.2 gas and the like are supplied
from the gas supply mechanism 60', as explained below; and thus,
these gases are discharged through the gas flow path 132 to the
processing space S through the gas discharge holes 131. The gas
discharge holes 131 are formed horizontally to supply the
processing gas into the bell jar 141. Further, the gas discharge
holes 131 may be formed to be tilted upward, to thereby supply the
processing gas towards the central portion of the bell jar 141.
[0108] The gas supply mechanism 60' for introducing a gas for
plasma processing into the processing space S has a gas supply
source, an opening/closing valve and a mass flow controller for
controlling a flow rate (all of them not, shown), e.g., like the
gas supply mechanism 60 shown in FIG. 2; and it supplies a
predetermined gas to the gas introducing member 130 through a gas
line 161. Further, valves and mass flow controllers of the
respective lines are controlled by using a controller (not
shown).
[0109] As a gas for plasma processing, there are illustrated Ar, Ne
and He that may be individually employed. Further, any of Ar, Ne
and He may be used together with H.sub.2, and any of them may be
used together with NF.sub.3. Among these, as described in FIG. 2,
it is preferable that Ar is used individually, or together with
H.sub.2. The gas for plasma processing is properly selected based
on a target to be etched.
[0110] The conductive member 147 serves as a facing electrode, and
at the same time, functions to pressurize the bell jar 141; and it
is made of aluminum, whose surfaces are anodized, aluminum,
stainless steel, titan and the like.
[0111] In the following, the bell jar 141 will now be explained in
detail.
[0112] In the present embodiment, a flatness of the bell jar 141 is
regulated to increase the in-surface uniformity in the etching by
improving the uniformity in the plasma.
[0113] Namely, the flatness K (=D/H), which is defined as a ratio
D/H between an inner diameter D of the side wall portion 141a of
the bell jar 141 and a height H of the central portion of the domed
ceiling wall portion 141b, is configured to be in the range of
1.60.about.9.25.
[0114] If the flatness K is smaller than 1.60, the in-surface
uniformity cannot be improved. Further, if the flatness K is
greater than 9.25, winding of the coil 143 required for producing a
plasma becomes difficult in practice.
[0115] Further, the flatness K1 (=D/H1), which is defined as a
ratio D/H1 between the inner diameter D of the cylindrical side
wall portion 141a of the bell jar 141 and a height H1 from the top
surface of the susceptor 21 in a central portion of the domed
ceiling wall portion 141b, is configured to be in the range of
0.90.about.3.85.
[0116] Under such a flatness condition, the number of windings of
the coil 143 may be consequently ten times or less, preferably
7.about.2 times, and more preferably, 4.about.2 times.
[0117] With respect to the bell jar 141, values of the height H of
the central portion of the domed ceiling wall portion 141b, the
height H1 from the top surface of the susceptor 21 in the central
portion of the domed ceiling wall portion 141b and the inner
diameter D of the cylindrical side wall portion 141a are, e.g.,
H=98 mm, H1=209 mm and D=450 mm, respectively. At this time, the
flatnesses K and K1 are 4.59 and 2.15, respectively.
[0118] Further, an example of dimensional relationships between
other parts is as described below. Given that an inside measurement
of height with respect to the domed portion of the bell jar 141 is
H2; a height in the cylindrical portion of the bell jar 141 is H3
(i.e., H=H2+H3); a thickness of the gas introducing member 130 is
H4; a height from the top surface of the susceptor 21 to a top
surface of the opening in the chamber 10' (a mounting surface of
the gas introducing member 130) is H5; and a height from the top
surface of the susceptor 21 to a top surface of the gas introducing
member 130 is H6, respective dimensional values and ratios thereof
are as described below.
[0119] Namely, a ratio K2 is H/H6, i.e., about 0.55.about.1.50. A
ratio K3 is H2/H3, i.e., 2.1 or less, preferably 0.85 or less, and
more preferably, 0.67 or less.
[0120] Further, a ratio K4 is H2/(H3+H6), i.e., below 0.75,
preferably 0.65 or less, and more preferably, about 0.55 or
less.
[0121] Still further, in case where H2 is about 29.about.74 mm,
H6+H3 is about 97.about.220 mm. In case where H3 is about 35 mm or
greater, H5+H4 is about 62.about.120 mm. In case where H2 is about
29 mm, if H3 is about 35.about.100 mm, H5 is about 0.about.72 mm,
and preferably, about 22.about.72 mm.
[0122] In case of employing such a bell jar 141 formed by the
ratios as mentioned above, a high plasma density area in an outer
peripheral portion inside the bell jar 141 is shifted towards the
wafer W, so that an area having uniformized plasma density can be
expanded. Accordingly, a plasma is uniformly generated in a part
where the wafer W is present, so that an etching uniformity gets
improved. For the same reason, it is effective for a wafer
(substrate) of a large diameter, particularly.
[0123] In the following, a processing operation by the plasma
processing apparatus 100' as configured above will be
discussed.
[0124] First, the gate valve 37 is opened to load the wafer W into
the chamber 10' by using a transfer arm (not shown), and the wafer
elevating pins 31 protruded from the susceptor 21 receive thereon
the wafer W. Subsequently, the wafer elevating pins 31 are lowered
to allow the wafer W to be mounted on the susceptor 21, and the
shadow rings 23 are lowered.
[0125] Thereafter, the gate valve 37 is closed to exhaust insides
of the chamber 10' and the bell jar 141 by using the gas exhaust
unit 39 to be kept at a predetermined depressurized state. In such
a depressurized state, a predetermined gas, e.g., an Ar gas,
supplied from the gas supply mechanism 60' is discharged to the
bell jar 141 from the gas discharge holes 131 of the gas
introducing member 130. At the same time, high frequency powers of,
e.g., 0.about.1000 W and 500.about.3000 W are supplied into the
electrode 24 inside the susceptor 21 and the coil 143 from the high
frequency power supply 25 for bias and the high frequency power
supply 144 for producing a plasma, respectively. Accordingly, an
electric field is generated between the coil 143 and the conductive
member 147, and the gas introduced into the bell jar 141 is excited
to ignite the plasma. After the ignition of the plasma, an induced
current flows through the bell jar 141 to generate the plasma
continuously, and a native oxide film formed on the wafer W, e.g.,
a silicon oxide formed on the silicon or a metal oxide film formed
on the metal film, is etched to be removed by the plasma. At this
time, a bias is applied to the susceptor 21 by the high frequency
power supply 25, and the wafer W is kept at a predetermined
temperature by the heater 28. The temperature is
20.about.800.degree. C., and preferably, 20.about.200.degree.
C.
[0126] At this time, a plasma density is
0.7.about.10.times.10.sup.10 atoms/cm.sup.3, and preferably,
1.about.6.times.10.sup.10 atoms/cm.sup.3. By performing a
processing for about 30 seconds by using such a plasma, a silicon
oxide film (SiO.sub.2) is removed by, e.g., about 10 nm.
[0127] As described above, by removing the impurity layer
containing oxides such as a native oxide film and the like,
adhesivity of a film to be formed may be improved, and an
electrical resistance value may be reduced.
[0128] Herein, in case of the present embodiment, the flatness K of
the bell jar 141 is set to 1.60.about.9.25, or the flatness K1 is
set to 0.90.about.3.85, as described above, so that the plasma
formed in the bell jar 141 spreads uniformly over the whole surface
of the wafer W. Further, since the high plasma density area in the
outer peripheral portion inside the bell jar 141 is shifted towards
the wafer W, an etching processing is performed uniformly on the
whole surface of the wafer W, and thus, the in-surface uniformity
in the etching is improved. In this case, by regulating R1 and R2
as 1600 mm.about.2200 mm and 20 mm.about.40 mm, respectively, and
particularly, making R1 large, a cross sectional shape of the bell
jar 141 becomes of a near rectangular flat shape and the plasma is
formed in the bell jar 141 to spread more uniformly over the whole
surface of the wafer W. Therefore, the etching processing is
performed uniformly on the whole surface of the wafer W by using
the plasma, so that the in-surface uniformity in the etching is
improved.
[0129] FIG. 10A shows a simulation result of an Ar.sup.+ density
distribution of Ar plasma in the bell jar, in case of the
conventional bell jar having a high height (the height H is 137 mm,
the inner diameter D is 450 mm and the number of windings of the
coil is ten times); and FIG. 10B shows a simulation result of an
Ar.sup.+ density distribution in the plasma with respect to the
bell jar 141 (the height H is 98 mm, the inner diameter D is 450 mm
and the number of windings of the coil is four times) of the
present embodiment.
[0130] These simulation results support the fact that the Ar.sup.+
density distribution spreads uniformly in the plane direction of
the wafer W and the in-surface uniformity in the etching of the
wafer W by the plasma is improved in case of the present embodiment
having more flat shape shown in FIG. 10B, as compared to the
conventional art of FIG. 10A.
[0131] Namely, for improving the etching uniformity, it is required
to uniformly generate the plasma (Ar.sup.+ ion density) in the top
surface area of the wafer. Therefore, it is preferable that the
wafer W is completely immersed in the area where the Ar.sup.+ ion
density is uniformly formed, in order to form the area having the
uniformized plasma.
[0132] Consequently, if the bell jar 141 is configured to be
expanded laterally, the plasma gets spread wider. But, the
apparatus becomes large, the plasma density is reduced, and more
power is required. Thus, an increase in the cost of the apparatus
is incurred.
[0133] In case of the present embodiment, since the flatnesses K
and K1 of the bell jar 141, the ratios K2.about.K4, and the height
H1 from the top surface of the mounting table to the ceiling
portion of the bell jar 141 are optimized, the plasma density may
be kept even at low cost and the uniformity may be improved without
scaling up the apparatus or increase in power consumption.
[0134] FIG. 11 shows an example of a relationship between the
height H1 from the top surface of the mounting table to the ceiling
portion of the bell jar 141 and the etching uniformity. As
illustrated in FIG. 11, the etching uniformity is substantially
constant until H1 becomes 210 mm, but it significantly decreases if
H1 becomes higher than 250 mm. Accordingly, in case of the present
embodiment, H1 is set to 209 mm as an example, as mentioned above,
so that good etching uniformity is obtained.
[0135] Further, in the present embodiment, the number of windings
of the coil 143 is reduced and the height of the bell jar 141 is
lowered to make the bell jar 141 flatter, but the chamber 10'
employs the configuration of the conventional art. The reason is
that by employing same common designs for the susceptor, the gate
valve and the like in the chamber as the ones used for other
processing apparatus, e.g., such as a film forming apparatus, it is
possible to cut the production cost of the chamber. Further, by
employing a same common external transfer mechanism for
loading/unloading the wafers into/from the chamber and a same
common connection structure to load-lock chambers in multiple
species of processing apparatus, e.g., film forming apparatus and
etching apparatus, that is, by standardizing them, it becomes easy
to form a multi-chamber apparatus by connecting multiple processing
apparatuses together.
[0136] In other words, in accordance with the plasma processing
apparatus of the present embodiment, since the chamber of the
conventional art is employed as it is, it is possible to realize
the improvement of the in-surface uniformity in the plasma
processing on the wafer while suppressing running cost increase as
well as maintaining the universality.
[0137] In the plasma processing apparatus of the present
embodiment, it is preferable that the identical gas introducing
mechanism to that in the first embodiment is employed. A
configuration thereof is shown in FIG. 12. The plasma processing
apparatus shown in the drawing employs the gas introducing
mechanism 50 of the first embodiment, instead of using the gas
introducing mechanism 50' shown in FIG. 9. Other configurations are
the same as in the FIG. 9.
[0138] Further, in the present embodiment, it is preferable to
prepare the same attaching and detaching mechanism as the attaching
and detaching mechanism 70 of the first embodiment.
Third Embodiment
[0139] In the following, a third embodiment of the present
invention will be explained. The third embodiment is characterized
by a mounting configuration of the semiconductor wafer W as a
substrate to be processed.
[0140] FIG. 13 is a schematic cross sectional view showing a
mounting configuration of the semiconductor wafer in the plasma
processing apparatus in accordance with the third embodiment of the
present invention. In the present embodiment, a cap shaped mask
plate 170 is provided on a susceptor 21 attachably and detachably
to form a wafer supporting portion 20''; and the wafer W is
configured to be mounted on a surface of the mask plate 170. Since
the mounting configuration of the semiconductor wafer or
configurations around the chamber are the same as in the second
embodiment, identical reference numerals in FIG. 13 will be used
for the corresponding parts having substantially same functions and
configurations of FIG. 10 in the second embodiment, and
explanations thereof will be simplified.
[0141] The mask plate 170 is made of a dielectric material such as
quartz (SiO.sub.2) or the like. The mask plate 170 is provided to
perform an initialization of the chamber 10' by performing a plasma
processing while the wafer W is not mounted, and to prevent
contaminants from being scattered from the susceptor 21 to the
wafer W. Specifically, it is effective in case when performing an
etching to remove the oxide on the silicon.
[0142] As described in the magnified cross sectional view of FIG.
14, a top surface of the mask plate 170 is configured to be flat
such that a wafer mounting region 170a making a contact with a rear
surface of the wafer W and an outer peripheral region 170b have the
same thickness (height) without having a step portion.
[0143] As an example, in case where a diameter of the wafer W is
300 mm, an outer diameter of the mask plate 170 is, e.g., 352
mm.
[0144] In the susceptor 21 and the mask plate 170, there are
formed, at positions corresponding to the wafer mounting region
170a, through holes 31b and 170c into which three wafer elevating
pins 31 (only two of them are shown) for supporting and elevating
the wafer W are inserted. The wafer elevating pins 31 are
configured to be popped out from or popped into the top surface of
the mask plate 170 via the through holes 31b and 170c.
[0145] As illustrated in FIG. 15, in the peripheral region 170b of
the top surface of the mask plate 170, there are almost
equi-spacedly arranged plural positioning projections 171 (six in
the present embodiment) to surround the outer periphery of the
wafer W along the circumferential direction, to thereby prevent a
position of the wafer W mounted on the wafer mounting region 170a
from being shifted off from each other. As illustrated in FIG. 14,
a diameter of a region, where the positioning projections 171 are
arranged, is set such that a gap G between the outer periphery of
the wafer W disposed at an inner side thereof and the respective
positioning projections 171 is 0.5.about.2 mm, and preferably, 1
mm.
[0146] As for dimensions of each positioning projection 171, the
height may be lower than the thickness of the wafer W, i.e., 0.775
mm or less, preferably 0.7 mm or less, and more preferably
0.05.about.0.3 mm or less; and the diameter is 0.2.about.5 mm. As
an example of the dimensions of each positioning projection 171,
the diameter is 2.4 mm and the height is 0.3 mm. In the surface of
the mask plate 170 having a diameter of 352 mm, an area occupied by
these positioning projections 171 is negligibly small. Namely, the
peripheral region 170b on the surface of the mask plate 170 is flat
and has a substantially same height as the wafer mounting region
170a.
[0147] In the wafer mounting region 170a on the top surface of the
mask plate 170, there are radially provided ventilation grooves 172
from the central portion. One ends of the ventilation grooves 172
communicate with the through holes 170c and 31b into which the
wafer elevating pins 31 are inserted. Further, when the wafer W is
mounted on the wafer mounting region 170a in the mask plate 170, an
atmosphere between the rear surface of the wafer W and the mask
plate 170 is rapidly discharged towards a rear surface of the
susceptor 21 via the ventilation grooves 172 and the through holes
170c and 31b. In this way, the wafer W can be prevented from being
shifted in an unstable movable state. Further, a stable and rapid
mounting operation may be performed.
[0148] Contrary to this, when the wafer W is levitated from the
mask plate 170 by an operation for elevating the wafer elevating
pins 31, an atmosphere of the rear surface of the susceptor 21 is
introduced into the rear surface of the wafer W via the through
holes 31b and 170c and the ventilation grooves 172. Accordingly, it
can be prevented that the rear surface of the wafer W comes to have
a negative pressure to generate an adsorption force, which opposes
the levitation of the wafer W, and thus the rapid levitating
operation of the wafer W may be realized.
[0149] Here, with respect to the mask plate 170 illustrated in
FIGS. 13.about.15, the wafer mounting region 170a making a contact
with the rear surface of the wafer W to be mounted and the outer
peripheral region 170b are configured to be flat with the same
thickness (height) without having a step portion. Therefore, an
impedance distribution inside the top surface of the mask plate 170
(susceptor 21) becomes uniform over the wafer mounting region 170a
and the outer peripheral region 170b when producing a plasma. For
the same reason, the density distribution of the plasma becomes
uniform over the top surface of the wafer mounting region 170a and
the outer peripheral region 170b; a nonuniformity in the
processing, such as a difference between etching rate at central
portion of the wafer W and that at peripheral portion thereof,
caused by a difference in the impedance distribution, can be
solved; and the in-surface uniformity in the plasma processing such
as an etching process can be improved over the whole surface of the
wafer W.
[0150] FIG. 16 is a graph showing a value of a height dimension Ts
(horizontal axis: unit mm) in a corresponding step portion, and a
nonuniformity NU (vertical axis: unit %, it is represented as a
percentage of the number of measurement results, which fall outside
the range of 1 .sigma., against the total measurement results; and
it is getting more uniform as it getting smaller) in an etching
result, in case where a step portion for positioning the wafer W is
formed in the wafer mounting region 170a of the mask plate 170.
[0151] As is clear from FIG. 16, if the value of Ts becomes small,
the nonuniformity NU % in the etching: gets small. Further, it can
be noted that if Ts is zero (it corresponds to a case where the
wafer mounting region 170a and the peripheral region 170b' are flat
without making the step portion), the nonuniformity becomes
minimized, and thus the in-surface uniformity becomes optimal.
[0152] Same as in the present embodiment, in case where the wafer
mounting configuration having the mask plate 170 is applied to the
plasma processing apparatus 100' having the flat bell jar 141 in
accordance with the second embodiment shown in FIG. 10, it is
expected that the in-surface uniformity is further improved due to
a synergy effect that the density distribution of the plasma is
uniform by using the flat bell jar 141.
[0153] Further, even in case where the wafer mounting configuration
having the mask plate 170 of the present embodiment is applied to
the conventional plasma processing apparatus having a bell jar
wherein the number of windings of the coil 143 is seven times or
more and the height thereof is relatively high, an effect of
improving the in-surface uniformity may be obtained.
[0154] Still further, the aforementioned embodiments are merely
intended to clarify the technology of the present invention. The
present invention is not limited to the aforementioned embodiments,
and various changes and modifications may be made without departing
from the spirit and scope of the invention.
[0155] For example, while the aforementioned embodiments describe
the case where the present invention is applied to the apparatus
performing a removal of the native oxide film, the present
invention may be applied to a plasma etching apparatus performing a
contact etching and the like, and further, it can be applied to an
additional plasma etching apparatus. Further, the semiconductor
wafer was explained as an example of an object to be processed, but
it is not limited thereto. The present invention may be employed in
other objects to be processed, e.g., an LCD substrate and the
like.
[0156] Further, it may be within the present invention that the
constituents of the aforementioned embodiments may be properly
combined, or a certain portion thereof may be removed without
departing from the spirit and scope of the invention.
* * * * *