U.S. patent application number 12/392237 was filed with the patent office on 2010-07-01 for plasma processing apparatus.
This patent application is currently assigned to HITACHI HIGH-TECHNOLOGIES CORPORATION. Invention is credited to Kazuyuki Hirozane, Takamasa Ichino, Tadamitsu Kanekiyo, Kenetsu Yokogawa.
Application Number | 20100163187 12/392237 |
Document ID | / |
Family ID | 42283459 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100163187 |
Kind Code |
A1 |
Yokogawa; Kenetsu ; et
al. |
July 1, 2010 |
PLASMA PROCESSING APPARATUS
Abstract
A plasma processing apparatus includes a vacuum chamber, a
sample table that places the sample in the vacuum chamber, and a
gas supply unit faced to the sample table and having a gas supply
surface with a diameter larger than that of the sample, wherein gas
injection holes each having identical diameter are provided
concentrically on the gas supply surface, a hole number density of
the gas injection holes present in an outer diameter position of
the sample or in an outside of the outer diameter position is made
higher than that of the gas injection holes present inside the
outer diameter position of the sample, and a diameter of the gas
injection holes present in the outer diameter position of the
sample or in the outside from the outer diameter position is larger
than that of the gas injection holes present inside the diameter of
the sample.
Inventors: |
Yokogawa; Kenetsu;
(Tsurugashima, JP) ; Ichino; Takamasa; (Kudamatsu,
JP) ; Hirozane; Kazuyuki; (Kudamatsu, JP) ;
Kanekiyo; Tadamitsu; (Kudamatsu, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
HITACHI HIGH-TECHNOLOGIES
CORPORATION
|
Family ID: |
42283459 |
Appl. No.: |
12/392237 |
Filed: |
February 25, 2009 |
Current U.S.
Class: |
156/345.34 |
Current CPC
Class: |
H01J 37/3244 20130101;
H01L 21/67069 20130101; H01J 37/32091 20130101 |
Class at
Publication: |
156/345.34 |
International
Class: |
C23F 1/08 20060101
C23F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2008 |
JP |
2008-331822 |
Claims
1. A plasma processing apparatus for applying a surface processing
to a sample, comprising: a vacuum chamber; a sample table that
places the sample in the vacuum chamber, and a gas supply unit
faced to the sample table and having a gas supply surface with a
diameter larger than that of the sample, wherein gas injection
holes each having identical diameter are provided concentrically on
the gas supply surface of the gas supply unit, and a hole number
density of the gas injection holes present in an outer diameter
position of the sample or in an outside of the outer diameter
position is made higher than that of the gas injection holes
present inside the outer diameter position of the sample.
2. The apparatus according to claim 1 wherein the hole number
density of the gas injection holes present in an outer diameter
position of the sample or in an outside of the outer diameter
position is present in a range from 1.5 to 4.0 times that of the
gas injection holes present inside the outer diameter position of
the sample.
3. The apparatus according to claim 1 wherein the gas injection
holes present in the outer diameter position of the sample or in
the outside of the outer diameter position are present in a range
of 1.0 to 1.1 times the diameter of the sample.
4. The apparatus according to claim 1 wherein an aspect ratio (D/L)
is equal to or greater than 2, where the diameter of sample is D,
and a distance from the sample to the gas supply surface is L.
5. A plasma processing apparatus for applying a surface processing
to a sample, comprising: a vacuum chamber; a sample table that
places the sample in the vacuum chamber; and a gas supply unit
faced to the sample table and having a gas supply surface with a
diameter larger than that of the sample, wherein gas injection
holes are provided concentrically on the gas supply surface of the
gas supply unit, and a diameter of the gas injection holes present
in an outer diameter position of the sample or in an outside from
the outer diameter position is larger than that of the gas
injection holes present inside from the outer diameter position of
the sample.
6. The apparatus according to claim 5 wherein a diameter of the gas
injection holes present in the outer diameter position of the
sample or in an outside of the outer diameter position is present
in a range of 1.1 to 1.5 times that of the gas injection holes
present inside the outer diameter position of the sample.
7. The apparatus according to claim 5 wherein the gas injection
holes present in the outer diameter position of the sample or in
the outside of the outer diameter position are present in a range
of 1.0 to 1.1 times the diameter of the sample.
8. The apparatus according to claim 5 wherein an aspect ratio (D/L)
is equal to or greater than 2, where the diameter of sample is D,
and a distance from the sample to the gas supply surface is L.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a plasma processing
apparatus to manufacture semiconductor devices, and in particularly
to a dry etching technique to etch semiconductor materials, such as
a silicon, a silicon dioxide film, etc., along a mask pattern shape
formed by a resist material etc.
[0002] The dry etching is a semiconductor micro-fabrication method
in which a processing gas is introduced into a vacuum chamber
having a vacuum decompression unit, the processing gas is turned
into a plasma by an electromagnetic wave to apply it to a sample to
be processed, a surface of the sample other than a mask portion is
etched to obtain a desirable shape. A processing uniformity on an
in-plane sample is affected by a plasma distribution, a temperature
distribution on the in-plane of the sample, a supplied gas
composition and flow rate distribution, etc.
[0003] Particularly, in the case of a parallel plate type plasma
processing apparatus, the processing gas is supplied from a shower
plate disposed so as to face the sample, and a gas supply
distribution of the gas supplied from the shower plate has an
effect on a process speed, a process shape, etc., since a distance
between the sample and the shower plate is relatively short.
[0004] As to using the above-mentioned characteristic,
JP-A-2006-41088 (corresponding to U.S. patent publication Nos.
2006/16559 and 2007/186972) has proposed a plasma processing
apparatus which controls independently the gas composition and flow
rate at a center portion and a periphery portion of the shower
plate, enhancing the in-plane uniformity of the sample, such as a
process shape.
[0005] FIG. 7 shows a shower plate as related art.
[0006] Normally, the shower plate has been designed that a
plurality of gas injection holes 2 are uniformly disposed on a
shower plate gas supply surface 5, such that the gas composition
and flow rate injected from every hole should be uniformed and a
gas supply condition applied per unit area of the sample is also
uniformed, basically.
[0007] Further, the gas supply amount is broadly controlled at the
center portion and periphery portion of the in-plane sample to
cancel an effect caused by a reactive product etc., realizing the
uniformity of the processed shape.
[0008] In the case of a gas supply distribution structure disclosed
in the JP-A-2006-41088, the gas composition and flow rate injected
from every hole are different in the two domains: the center
portion and the periphery portion, but the gas having the same gas
composition and flow rate is injected from the holes present in the
respective domains.
SUMMARY OF THE INVENTION
[0009] There is a tendency for the gas supply amount at the
periphery portion of the sample to relatively go down compared with
the center portion and its vicinity thereof, since the gas
injection holes to be formed on the shower plate are basically
disposed in uniformity.
[0010] Particularly, in the case of a narrow-gap type apparatus,
there sometimes arises a problem to occur a non-uniformity shape at
the periphery portion of the sample by causing the non-uniformity
of gas supply amount.
[0011] FIG. 3 shows a relation of an aspect ratio (D/L) and a
relative molecule flux, where a wafer (sample) diameter is D(300
mm), and a distance from the wafer to the shower plate is L. This
is a result in which a relative amount of the gas molecules reached
to the faced wafer is calculated by one dimension, in the case
where it assumes that the gas molecules injected uniformly from the
gas injection holes of the shower plate are isotropically diffused,
and it also assumes that the shower plate having the gas injection
holes faced to the wafer has the same diameter and the number of
holes per unit area is uniformity.
[0012] As shown in FIG. 3, it is appreciated that the relative
amount of the gas molecules reached to the wafer surface is
relatively deficient at the wafer periphery portion when the aspect
ratio becomes large. That is, it has become clear that the relative
deficiency of the gas supply amount at the edge portion of the
wafer occurs from a condition where the distance between the wafer
and shower plate is equal to or less than 300 mm, where the aspect
ratio is equal to or greater than 1, or the wafer diameter is 300
mm (.phi.300 mm).
[0013] As to a solution method for the problem indicated on FIG. 3,
it is possible to be thought of a method such that a domain of the
gas injection holes formed on the shower plate is expanded in
relation to the diameter of sample.
[0014] FIG. 4 shows a relation between a gas injection domain
diameter and the relative molecule flux.
[0015] This is a result of the case where the wafer diameter is 300
mm, the gas injection holes are disposed uniformly on the shower
plate, and the distance L between the wafer and shower plate is 24
mm (aspect ratio D/L=12.5).
[0016] As shown in FIG. 4, for a purpose of obtaining a sufficient
gas supply uniformity in this method that expands the diameter of
the gas injection hole domain, it has become clear that the gas
injection hole domain diameter requires about 1.5 times the wafer
diameter D, that is, the gas injection hole domain diameter is set
substantially to equal to or greater than 450 mm (.phi.450 mm).
[0017] In fact, since the expansion of the gas injection domain
diameter incurs a large size apparatus caused by a large-sized
shower plate and the shower plate is normally exchanged regularly
as a consumable supply, the cost of the consumable supply increases
by causing the large size, as a problem, and the expansion is not
helpful to practically solve the problem.
[0018] An object of the invention is to solve the gas supply
deficiency occurred at the periphery portion of the sample when the
gas is supplied from the shower plate, and to provide a plasma
processing apparatus capable of enhancing the in-plane uniformity
of processing accuracy on the sample.
[0019] Particularly, the invention is to provide a plasma
processing apparatus having both enhancement of the in-plane
uniformity of the sample in the processing characteristic and cost
reduction of the consumable supply by restraining the expansion of
the shower plate diameter in minimum and improving the gas supply
uniformity to the in-plane sample.
[0020] According to one aspect of the invention to solve the
problem, a plasma processing apparatus for applying a surface
processing to a sample, includes a vacuum chamber, a sample table
to place the sample in the vacuum chamber, and a gas supply unit
faced to the sample table and having a gas supply surface with a
diameter larger than that of the sample, in which gas injection
holes each having identical diameter are provided concentrically on
the gas supply surface of the gas supply unit, and a hole number
density of the gas injection holes present in an outer diameter
position of the sample or in an outside of the outer diameter
position is made higher than that of the gas injection holes
present inside the outer diameter position of the sample.
[0021] According to another aspect of the invention, a plasma
processing apparatus for applying a surface processing to a sample,
includes a vacuum chamber, a sample table to place the sample in
the vacuum chamber, and a gas supply unit faced to the sample table
and having a gas supply surface with a diameter larger than that of
the sample, in which gas injection holes are provided
concentrically on the gas supply surface of the gas supply unit,
and a diameter of the gas injection holes present in an outer
diameter position of the sample or in an outside from the outer
diameter position is larger than that of the gas injection holes
present inside from the outer diameter position of the sample.
[0022] According to the invention, a uniformed gas supply
distribution is given to the entire surface of the sample without
making the apparatus large and also making the shower plate large
as a change part, realizing the uniformity of processing rate and
processing shape of the sample.
[0023] The other objects, features and advantages of the invention
will become apparent from the following description of the
embodiments of the invention taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a section view of a plasma processing apparatus in
the invention;
[0025] FIG. 2 is a schematic view of a shower plate in a first
embodiment of the invention;
[0026] FIG. 3 is an explanatory diagram of a relative molecule flux
distribution on a wafer surface in a condition obtained from a
ratio (D/L) where a wafer diameter D and a distance L between the
wafer and the shower plate;
[0027] FIG. 4 is a diagram showing an effect of a gas injection
domain diameter in relation to the wafer diameter;
[0028] FIG. 5 is a diagram for explaining an advantage of the
invention;
[0029] FIG. 6 is a diagram for explaining an advantage of the
invention;
[0030] FIG. 7 is a schematic view of a related shower plate;
[0031] FIG. 8 is a diagram showing the relative molecule flux on
the wafer surface when a gas-injection-hole number density is made
increased at 280 mm (.phi.280 mm) and its vicinity of the shower
plate;
[0032] FIG. 9 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 290 mm (.phi.290 mm) and its vicinity of the
shower plate;
[0033] FIG. 10 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 300 mm (.phi.300 mm) and its vicinity of the
shower plate;
[0034] FIG. 11 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 320 mm (.phi.320 mm) and its vicinity of the
shower plate;
[0035] FIG. 12 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 330 mm (.phi.330 mm) and its vicinity of the
shower plate;
[0036] FIG. 13 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 340 mm (.phi.340 mm) and its vicinity of the
shower plate;
[0037] FIG. 14 is a diagram showing the relative molecule flux on
the wafer surface when the gas-injection-hole number density is
made increased at 360 mm (.phi.360 mm) and its vicinity of the
shower plate; and
[0038] FIG. 15 is a schematic view of the shower plate in a second
embodiment of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0039] Hereinafter, embodiments of the invention will be described
with reference to the drawings.
Embodiment 1
[0040] A first embodiment of the invention will be described with
use of FIG. 1 and FIG. 2.
[0041] FIG. 1 is shows a section view of a plasma processing
apparatus in one embodiment of the invention. The plasma processing
apparatus includes an electrostatic chucking function built-in
electrode (sample table) 15 for placing a sample 7 in a vacuum
chamber 24 and a shower plate (gas supply unit) 1 faced to the
sample table 15. In this way, a 200 MHz high-frequency power is
supplied from a discharge-use high-frequency power source 13 to a
conductor-type antenna 12 incorporated with a plate 8 and a
dispersion plate 11 to turn a gas supplied from the shower plate 1
into a plasma in a discharge space 14. Further, a 4 MHz
high-frequency voltage is applied to the sample 7 from a
high-frequency power source 16 via the electrostatic chucking
function built-in electrode 15 to accelerate ions in the plasma and
to be incident to the surface of the sample 7. The 4 MHz
high-frequency voltage is also applied independently to the antenna
12 from a high-frequency power source 17 by superimposing with a
discharge-use 200 MHz high-frequency power, so that an ion energy
in the plasma incident to the surface of shower plate 1 is
controlled independently from a plasma generation and a bias
condition of the sample. The antenna 12 and electrostatic chucking
function built-in electrode 15 are also controlled respectively in
temperature by insulation type liquid cooling circulating functions
21, 22.
[0042] The shower plate 1 is formed by silicon. The plate 8 is
disposed on an upper stage of the shower plate 1, and the plate 8
has holes matched with the same position of gas injection holes 2
formed on the shower plate 1 and slightly larger than the gas
injection holes 2 in diameter. The dispersion plate 11 is further
disposed on the upper stage of the plate 8, and the dispersion
plate 11 forms a gas dispersion layer 10 to disperse the gas
supplied from a gas supply portion 9. The gas supply portion 9 is
provided independently for an inside domain and an outside domain
of the sample 7, and a flow rate and a gas composition can be
controlled independently at the inside and outside domains of the
sample 7. The inside domain and outside domain are also divided by
a barrier in such that a form domain area of the respective gas
injection holes 2 in the inside and outside domains is
substantially equal. In the case of this embodiment, the apparatus
will be described with two domains: the inside domain and outside
domain, and the domain may not be divided, but also divided into
more than three domains. In addition, reference numerals 18, 19 and
20 denote an automatic matching device, 6 denotes a shower plate
fixing screw hole, 23 denotes a silicon-made focus ring, 25 denotes
an insulation material, and 27 denotes an earth plate.
[0043] In the case of FIG. 1, a silicon wafer of 300 mm in diameter
is used for the sample. The gas injection holes 2 formed on the
shower plate 1 are formed within a range of 314 mm (.phi.314 mm) in
diameter, the inside of which is the inside domain of 200 mm
(.phi.200 mm), and the outside of which is the outside domain. The
gas dispersion layer 10 is also formed independently for the inside
and outside domains such that the gas is dispersed uniformly in the
respective inside and outside domains.
[0044] FIG. 2 shows a layout of the gas injection holes 2 on the
surface of shower plate 1, in which a diameter of the gas injection
hole 2 is 0.5 mm, and a thickness of the domain where the gas
injection holes 2 are formed on the shower plate 1 is 10 mm. The
diameter of the gas injection holes 2 formed on a shower plate gas
supply surface 5 is all the same. The gas injection holes 2 are
also formed in concentricity and in an equal interval (10 mm pitch)
from a shower plate center 3. The number of gas injection holes
formed on the circumferences is substantially proportional to the
circumference from the center to the periphery and its vicinity.
Therefore, the number of gas injection holes per unit area on the
shower plate 1 is substantially the same in the layout, from the
center to the periphery and its vicinity. The diameter of shower
plate gas supply surface 5 is made larger than that of the sample
7.
[0045] In the case of the constitution in FIG. 2, the total number
of gas injection holes of the outside domain in the periphery
domain is about twice that of the inside domain. Therefore, the gas
is flown into the outside domain by the flow rate having about
twice that of the inside domain, so that the gas flow rate injected
from every gas injection hole becomes equal at both the inside and
outside domains.
[0046] According to the above-mentioned constitution, the gas
injected from the gas injection holes 2 is substantially the same
in the flow rate and gas composition at the inside and outside
domains of the sample 7. A gas condition (flow rate and
composition) distribution produced by supplying the gas to the
surface of the sample 7 depends on a density of number of the gas
injection holes 2. In the case of this embodiment, the apparatus
will be described with a case where the gas flow rate injected from
every gas injection hole 2 is equal. However, it is not necessarily
to make the gas flow rate equal, injected from every gas injection
hole 2, since an oxygen flow rate is sometimes changed at the
inside and outside domains, for example, for a purpose of
correcting a deposition distribution caused by a reactive
product.
[0047] In the case of this embodiment, as to a position
corresponding to an edge portion of the sample 7, a hole number
density per unit length on two outermost circumferences formed with
the gas injection holes 2 is set to about twice that of the other
circumferences. A pitch between the gas injection holes 2 formed on
the other circumferences is 10 mm, while the pitch between the
holes 2 formed on the two outermost circumferences is 7 mm.
[0048] In consequence, the hole number density of the gas injection
holes 2 facing to the edge portion of the sample 7 increases by
about 2.85 times (density (twice) of circumferential
direction.times.density (10 mm/7 mm) of diametrical direction),
compared with the other domains.
[0049] That is, a uniformity gas supply is carried out at the
inside domain of the sample 7 since the gas injection holes 2 are
disposed on the inside domain with an equal density, however, a
large volume gas, much more than the other domains, is supplied to
the edge portion of the sample 7 at the outside domain since the
density of the gas injection holes 2 formed on the edge portion of
the sample 7 is high.
[0050] FIG. 5 shows a calculation result of the relative molecule
flux at the wafer edge portion in the case of the shower plate in
the invention and the shower plate as related art.
[0051] FIG. 5 shows the case where a wafer diameter D is 300 mm
(.phi.300 mm) and a distance L between the wafer and the shower
plate is 24 mm (aspect ratio D/L=12.5).
[0052] As shown in FIG. 5, it can be confirmed that a gas supply
amount deficiency is made up for the wafer edge portion and its
vicinity to supply uniformly the gas to the entire wafer surface,
in the case of the shower plate 1 of the invention. On the other
hand, the gas supply amount is relatively short at the wafer edge
portion and its vicinity, compared with the center portion of the
wafer, in the case of the related shower plate. This is assumed
that an exhaust velocity becomes fast at a long circumference wafer
edge portion, compared with the center portion of the wafer, when
the gas supplied from the shower plate 1 is exhausted from the
periphery of the wafer. The gas injected from the periphery portion
reaches to a center domain as isotropically diffused, however, it
is assumed that there is no gas supply from the outside other than
the outermost circumference formed with the gas injection holes
2.
[0053] In this way, by using the shower plate 1 in the invention,
it is possible that the gas is supplied uniformly, therefore, it
has become clear that the shower plate 1 is useful to make an
etching characteristic uniformed.
[0054] Particularly, as used with a narrow-gap type opposite
electrode structure, in the case of an etching mechanism (a silicon
dioxide film etching by using a phlorocabon-based gas etc.) of
which the etching characteristic depends largely on the supplied
gas flow rate rather than a gas pressure, a difference of an
etching rate and etching shape can be restrained within the
in-plane wafer.
[0055] FIG. 6 shows an etching rate distribution of a TEOS film in
the case of the shower plate 1 in the invention and the shower
plate as related art.
[0056] In the case of using the shower plate 1 of the invention,
the gas flow rate of the outside domain is set to about twice that
of the inside domain, that is, an inside flow rate is set to Ar=500
sccm, C.sub.4F.sub.8=15 sccm, O.sub.2=15 sccm, and an outside flow
rate is set to Ar=1000 sccm, C.sub.4F.sub.8=30 sccm, O.sub.2=30
sccm, in accordance with a gas injection hole number ratio (about
twice), since the gas supply amount injected from every gas
injection hole 2 is made equal for all of the holes 2 formed on the
inside and outside domains.
[0057] On the other hand, in the case of using the related shower
plate, the same gas flow rate is supplied to both the inside and
outside domains, that is, the inside and outside flow rates are of
an Ar/C.sub.4F.sub.8/O.sub.2 mixed gas containing Ar=500 sccm,
C4F8=15 sccm, O2=15 sccm, since the number of the gas injection
holes at the inside domain is substantially equal to that of the
outside domain.
[0058] As shown in FIG. 6, in the case of using the related shower
plate, the etching rate at the wafer edge portion is lowered, and
an etching rate uniformity is as much as 8%. In the case of using
the shower plate 1 of the invention, no effect is given to the
etching rate at a wafer center domain, the etching rate at the
wafer edge portion is increased, and the etching rate uniformity is
improved to as much as 3%.
[0059] In the case of the invention, it is possible to select an
optimal gas supply distribution in response to processing objects
and processing conditions, by changing the gas-injection-hole
number density so as to adapt the etching characteristic.
[0060] Next, the following description will be concerned with an
optimization for the gas-injection-hole number density and an
optimization for the domain on which the gas-injection-hole number
density is made increased.
[0061] FIG. 8 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 280 mm (.phi.280 mm) and its
vicinity of the shower plate 1.
[0062] FIG. 9 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 290 mm (.phi.290 mm) and its
vicinity of the shower plate 1.
[0063] FIG. 10 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 300 mm (.phi.300 mm) and its
vicinity of the shower plate 1.
[0064] FIG. 11 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 320 mm (.phi.320 mm) and its
vicinity of the shower plate 1.
[0065] FIG. 12 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 330 mm (.phi.330 mm) and its
vicinity of the shower plate 1.
[0066] FIG. 13 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 340 mm (.phi.340 mm) and its
vicinity of the shower plate 1.
[0067] FIG. 14 shows a calculation result of the relative molecule
flux on the wafer surface in the case where the gas-injection-hole
number density is increased at 360 mm (.phi.360 mm) and its
vicinity of the shower plate 1.
[0068] As shown in FIG. 8 and FIG. 9, the gas-injection-hole number
density is increased to thereby increase the gas supply amount at
the wafer edge portion in the inside domain inside the wafer
diameter or the wafer outer diameter position. This causes the gas
supply amount to increase the inside, but it has become clear that
the gas supply distribution is slightly improved.
[0069] On the other hand, as shown in FIG. 10 to FIG. 14, the
gas-injection-hole number density is increased to increase the gas
supply amount at the wafer edge portion in the domain of the wafer
diameter, that is, the wafer outer diameter position, or the domain
outside the wafer outer diameter position. It has become clear that
the uniformity gas supply distribution is obtained in the wafer
domain.
[0070] However, as shown in FIG. 13 and FIG. 14, in the case where
the gas injection hole is added to the domain at 340 mm (.phi.340
mm) or more, it is necessary to also increase the gas supply amount
since a necessary increased number caused by the additional
position gas-injection-hole number density becomes equal to or
greater than 4 times. Therefore, the apparatus is subject to an
increase of gas consumed amount and an increase of the strain on
the exhaust performance.
[0071] In consequence, as shown in FIG. 10 to FIG. 12, it is
desirable to increase the gas-injection-hole number density in a
range of about 300 mm (.phi.300 mm) to 330 mm (.phi.330 mm), that
is, as much as 1.0 to 1.1 times the wafer diameter.
[0072] Further, the increase of the gas-injection-hole number
density varies in response to the processing objects and processing
conditions. However, the gas-injection-hole number density
increases in the range of 1.5 to 4 times to thereby optimize the
uniformity of the etching characteristic, and the gas consumed
amount can be restrained.
Embodiment 2
[0073] A second embodiment of the invention will be described with
use of FIG. 15.
[0074] FIG. 15 is a schematic diagram showing a shower plate 1 in
the second embodiment of the invention.
[0075] In the case of this embodiment, each diameter of gas
injection holes 27 faced to the wafer edge portion and formed on
the periphery portion of the shower plate 1 is 1.3 times that of
the other gas injection holes 2, that is, the hole diameter at the
periphery portion is 0.65 mm while the other hole diameter is set
to 0.5 mm, and the gas-injection-hole number density is set to
uniformity. In the case of the first embodiment, the gas supply
amount to the wafer edge portion is adjusted by the
gas-injection-hole number density of the gas injection holes 4 each
having the same diameter and formed at the periphery portion of the
shower plate 1. In the case of the second embodiment, the gas
supply amount is adjusted by the hole diameter.
[0076] A conductance at a time when the gas passes through the gas
injection holes 2 of the shower plate 1 increases in proportion to
the 3 to 4 power of the hole diameter (3 power in the case of
molecule flow, and the 4 power in the case of viscous flow).
Practically, the conductance becomes a middle value (the 3.5 power
in a middle flow) between the molecule flow and the viscous
flow.
[0077] Therefore, it is possible to obtain the same effect as
increased the gas-injection-hole number density by expanding the
hole diameter, even in the same gas-injection-hole number
density.
[0078] In the case of the second embodiment, the gas-injection-hole
number density is the same at the periphery portion and the other
portion, and the hole diameter of the periphery portion is 1.3
times that of the other portion, so that the gas supply amount at
the periphery portion can be enhanced by about 2.85 times.
[0079] As with the first embodiment, the expansion amount of the
hole diameter can be changed by the processing objects and
processing conditions. For a purpose of increasing the
gas-injection-hole number density from 1.5 to 4.0 times, that is,
increasing the gas supply amount from 1.5 to 4.0 times, the hole
diameter is set to a range from 1.1 times (1/3.5 power of
1.5=1.123) to 1.5 times (1/3.5 power of 4=1.486), so that the
uniformity of the etching characteristic can be optimized.
[0080] Further, the domain on which the gas injection hole diameter
is expanded can be ranged desirably from 1.0 to about 1.1 times,
which is similar to the first embodiment.
[0081] The invention relates to a semiconductor device
manufacturing apparatus, and in particularly to a plasma etching
apparatus to apply an etching processing to a semiconductor
material masked with a pattern drawn by the lithography technique.
According to the invention, it is possible to enhance the
processing characteristic at the silicon wafer edge portion as a
sample, particularly, the uniformity of the processing rate and
processing shape. From the above-mentioned advantages of the
invention, a non-defective product acquired rate is enhanced for
the silicon wafer edge portion, and a processing yield of the
etching apparatus can be enhanced.
[0082] It should be further understood by those skilled in the art
that although the foregoing description has been made on
embodiments of the invention, the invention is not limited thereto
and various changes and modifications may be made without departing
from the spirit of the invention and the scope of the appended
claims.
* * * * *