U.S. patent application number 13/415753 was filed with the patent office on 2012-06-28 for dual zone gas injection nozzle.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Philip A. Bottini, Roger Curtis, Wei Liu, Hanh D. Nguyen, Son T. Nguyen, Johanes S. Swenberg.
Application Number | 20120164845 13/415753 |
Document ID | / |
Family ID | 40787298 |
Filed Date | 2012-06-28 |
United States Patent
Application |
20120164845 |
Kind Code |
A1 |
Liu; Wei ; et al. |
June 28, 2012 |
DUAL ZONE GAS INJECTION NOZZLE
Abstract
The present invention generally provides apparatus and method
for processing a substrate. Particularly, the present invention
provides apparatus and methods to obtain a desired distribution of
a process gas. One embodiment of the present invention provides an
apparatus for processing a substrate comprising an injection nozzle
having a first fluid path including a first inlet configured to
receive a fluid input, and a plurality of first injection ports
connected with the first inlet, wherein the plurality of first
injection ports are configured to direct a fluid from the first
inlet towards a first region of a process volume, and a second
fluid path including a second inlet configured to receive a fluid
input, and a plurality of second injection ports connected with the
second inlet, wherein the second injection ports are configured to
direct a fluid from the second inlet towards a second region of the
process volume.
Inventors: |
Liu; Wei; (San Jose, CA)
; Swenberg; Johanes S.; (Los Gatos, CA) ; Nguyen;
Hanh D.; (San Jose, CA) ; Nguyen; Son T.; (San
Jose, CA) ; Curtis; Roger; (Stockton, CA) ;
Bottini; Philip A.; (Santa Clara, CA) |
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
40787298 |
Appl. No.: |
13/415753 |
Filed: |
March 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11960166 |
Dec 19, 2007 |
8137463 |
|
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13415753 |
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Current U.S.
Class: |
438/777 ;
257/E21.293; 257/E21.331; 438/798 |
Current CPC
Class: |
H01J 37/32449 20130101;
H01J 37/3244 20130101 |
Class at
Publication: |
438/777 ;
438/798; 257/E21.293; 257/E21.331 |
International
Class: |
H01L 21/318 20060101
H01L021/318; H01L 21/263 20060101 H01L021/263 |
Claims
1. A method for processing a substrate, comprising: positioning a
substrate in a process volume within a chamber; and flowing a
processing gas to the process volume through an injection assembly,
wherein the flowing a processing gas comprises: flowing a first
portion of the processing gas to a first region of the process
volume through a plurality of first injection ports; flowing a
second portion of the processing gas to a second region of the
process volume through a plurality of second injection ports; and
adjusting a ratio of the first portion and the second portion to
achieve a desired distribution of the processing gas within the
process volume.
2. The method of claim 1, further comprising generating a plasma of
the processing gas within the process volume.
3. The method of claim 1, wherein the flowing a processing gas
further comprises using a controllable splitter to split the
processing gas into the first portion and the second portion.
4. The method of claim 1, wherein the injection assembly is
disposed above a center of the substrate being processed, the
plurality of first injection ports are directed perpendicularly to
the substrate near the center, and the plurality of second
injection ports are directed parallel to the substrate in a radial
manner.
5. The method of claim 1, wherein the flowing a processing gas
further comprises adjusting a total flow of the processing gas to
achieve the desired distribution of the processing gas.
6. The method of claim 1, wherein the plurality of first injection
ports flow the processing gas in a direction perpendicular to the
plurality of second injection ports.
7. The method of claim 1, wherein each of injection ports of the
plurality of first injection ports are directed parallel to one
another.
8. The method of claim 1, wherein the chamber is a plasma
chamber.
9. The method of claim 8, further comprising performing a
nitridation process on the substrate.
10. The method of claim 9, further comprising applying RF power to
a coil assembly positioned within the chamber while flowing the
processing gas through the injection assembly.
11. A method for processing a substrate, comprising: positioning a
substrate in a process volume within a chamber; flowing a
processing gas to the process volume through an injection assembly,
wherein the flowing a processing gas comprises: flowing a first
portion of the processing gas to a first region of the process
volume through a plurality of first injection ports; flowing a
second portion of the processing gas to a second region of the
process volume through a plurality of second injection ports; and
adjusting a ratio of the first portion and second portion to
achieve a desired distribution of the processing gas within the
process volume; and applying RF power to a coil assembly positioned
within the chamber to ionize the first portion of the processing
gas and the second portion of the processing gas.
12. The method of claim 11, wherein the injection ports of the
plurality of first injection ports are directed parallel to one
another.
13. The method of claim 11, wherein the flowing a processing gas
further comprises using a controllable splitter to split the
processing gas into the first portion and the second portion.
14. The method of claim 11, wherein the injection assembly is
disposed above a center of the substrate being processed, the
plurality of first injection ports are directed perpendicularly to
the substrate near the center, and the plurality of second
injection ports are directed parallel to the substrate in a radial
manner.
15. The method of claim 11, wherein the flowing a processing gas
further comprises adjusting a total flow of the processing gas to
achieve the desired distribution of the processing gas.
16. The method of claim 11, wherein each of injection ports of the
plurality of first injection ports are directed parallel to one
another.
17. A method for performing a plasma nitridation process on a
substrate, comprising: positioning a substrate having a silicon
dioxide gate dielectric thereon in a process volume within a
chamber; and flowing nitrogen gas to the process volume through an
injection assembly, wherein the flowing a nitrogen gas comprises:
flowing a first portion of the nitrogen gas to a first region of
the process volume through a plurality of first injection ports;
flowing a second portion of the nitrogen gas to a second region of
the process volume through a plurality of second injection ports;
and adjusting a ratio of the first portion and second portion to
achieve a desired distribution of the processing gas within the
process volume; ionizing the first portion of the nitrogen gas and
the second portion of the nitrogen gas; and diffusing the ionized
nitrogen gas into the silicon dioxide gate dielectric film.
18. The method of claim 17, wherein the flowing a nitrogen gas
further comprises adjusting a total flow of the nitrogen gas to
achieve the desired distribution of the nitrogen gas.
19. The method of claim 17, wherein each of injection ports of the
plurality of first injection ports are directed parallel to one
another.
20. The method of claim 17, wherein the injection assembly is
disposed above a center of the substrate being processed, the
plurality of first injection ports are directed perpendicularly to
the substrate near the center, and the plurality of second
injection ports are directed parallel to the substrate in a radial
manner.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of co-pending
U.S. patent application Ser. No. 11/960,166, filed Dec. 19, 2007,
which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
method and apparatus for processing a semiconductor substrate. More
particularly, embodiments of the present invention provide method
and apparatus for processing a semiconductor substrate using
inductively coupled plasma technology with improved uniformity.
[0004] 2. Description of the Related Art
[0005] Plasma reactors used to fabricate semiconductor
microelectronic circuits can employ RF (radio frequency)
inductively coupled fields to maintain a plasma formed from a
processing gas. Conventional inductively coupled plasma reactors
generally includes a vacuum chamber having a side wall and a
ceiling, a workpiece support pedestal within the chamber and
generally facing the ceiling, a gas inlet capable of supplying a
process gas into the chamber, and one or more coil antennas
overlying the ceiling. The one or more coil antennas are generally
wound about an axis of symmetry generally perpendicular to the
ceiling. A RF plasma source power supply is connected across each
of the coil antennas. Sometimes, the reactor may include an inner
coil antenna overlying the ceiling and surrounded by an outer coil
antenna.
[0006] Typically, a high frequency RF source power signal is
applied to the one or more coil antennas near the reactor chamber
ceiling. A substrate disposed on a pedestal within the chamber has
a bias RF signal applied to it. The power of the signal applied to
the coil antenna primarily determines the plasma ion density within
the chamber, while the power of the bias signal applied to the
substrate determines the ion energy at the wafer surface.
[0007] Typically with "inner" and "outer" coil antennas, the coils
are distributed radially or horizontally (rather than being
confined to a discrete radius) so that their radial location is
diffused accordingly. The radial distribution of plasma ion
distribution is changed by changing the relative apportionment of
applied RF power between the inner and outer antennas. However, it
becomes more difficult to maintain a uniform plasma ion density
across the entire wafer surface as wafers become larger and device
feature become smaller.
[0008] FIG. 1 schematically illustrates a non-uniformity problem
encountered by typical inductively coupled plasma reactors. FIG. 1
is a result showing nitrogen dosages across a substrate after
nitridation processes preformed in a typical inductively coupled
plasma reactor. The nitridation processes is performed to silicon
dioxide gate dielectric film formed on a substrate. The substrate
is positioned in a vacuum chamber capable of generating inductively
coupled plasma. Nitrogen gas is flown to the plasma chamber and a
plasma is struck while the flow continues. The nitrogen radicals
and/or nitrogen ions in the nitrogen plasma then diffuse and/or
bombard into the silicon dioxide gate dielectric film.
[0009] FIG. 1 is a diameter scan chart showing nitrogen dosage
(Ndose) along a diameter of a 300 mm substrate after nitridation
performed in an inductively coupled plasma reactor. The diameter
scan chart of FIG. 1 has an "M" shape illustrating a low dosage
near the center of the substrate. The center drop of the M shape is
mainly affected by the gas supply near the center region.
[0010] Therefore, there is a need for apparatus and method for
processing a semiconductor substrate using inductively coupled
plasma technology with improved uniformity.
SUMMARY OF THE INVENTION
[0011] The present invention generally provides apparatus and
method for processing a substrate. Particularly, the present
invention provides apparatus and methods to obtain a desired
distribution of a process gas in inductive plasma reactor.
[0012] One embodiment of the present invention provides an
apparatus for processing a substrate comprising a chamber body
defining a process volume, and an injection nozzle assembly at
least partially disposed in the process volume, the injection
nozzle assembly having a first fluid path including a first inlet
configured to receive a fluid input, and a plurality of first
injection ports connected with the first inlet, wherein the
plurality of first injection ports are configured to direct a fluid
from the first inlet towards a first region of the process volume,
and a second fluid path including a second inlet configured to
receive a fluid input, and a plurality of second injection ports
connected with the second inlet, wherein the second injection ports
are configured to direct a fluid from the second inlet towards a
second region of the process volume.
[0013] Another embodiment of the present invention provides an
apparatus for processing a substrate comprising a chamber body
defining a process volume, a substrate pedestal disposed in the
process volume, and a gas supply assembly in fluid communication
with the process volume, wherein the gas supply assembly comprises
a nozzle disposed substantially above a center of the substrate
pedestal, wherein the nozzle has a plurality of first injection
ports configured to direct a processing gas to a central region on
above the substrate pedestal, and a plurality of second injection
ports configured to direct the processing gas to an edge region
above the substrate pedestal, and a flow control unit configured to
adjust a ratio of the processing gas flown to the plurality of
first injection ports and the processing gas flown to the plurality
of second injection ports.
[0014] Yet another embodiment of the present invention provides a
method for processing a substrate comprising providing a process
chamber defining a process volume, positioning the substrate in the
process volume, and flowing a processing gas to the process volume
through an injection assembly, wherein flowing the processing gas
comprises flowing a first portion of the processing gas to a first
region of the process volume through a plurality of first injection
ports, flowing a second portion of the processing gas to a second
region of the process volume through a plurality of second
injection ports, and adjusting a ratio of the first portion and
second portion to achieve a desired distribution of the processing
gas within the process volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0016] FIG. 1 (prior art) schematically illustrates a
non-uniformity problem encountered by typical inductively coupled
plasma reactors.
[0017] FIG. 2 schematically illustrates a sectional side view of a
plasma reactor in accordance with one embodiment of the present
invention.
[0018] FIG. 3 schematically illustrates a partial sectional side
view of a plasma reactor having an injection assembly in accordance
with one embodiment of the present invention.
[0019] FIG. 4A schematically illustrates a sectional top view of a
nozzle in accordance with one embodiment of the present
invention.
[0020] FIG. 4B schematically illustrates a sectional side view of
the nozzle of FIG. 4A.
[0021] FIGS. 5A-5C are charts showing results of a nitridation
process using a plasma reactor having an injection assembly in
accordance with one embodiment of the present invention.
[0022] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0023] The present invention generally provides apparatus and
methods for processing a semiconductor substrate using inductively
coupled plasma. Embodiments of the present invention provide
inductively coupled plasma reactors having features that provide
improved uniformity. Particularly, the inductively coupled plasma
reactors of the present invention comprises an gas supply assembly
having independently adjustable gas injection ports.
[0024] FIG. 2 schematically illustrates a sectional side view of a
plasma reactor 100 in accordance with one embodiment of the present
invention. The plasma reactor 100 generally comprises a reactor
chamber 101 and an antenna assembly 102 positioned above the
reactor chamber 101. The antenna assembly 102 is configured to
generate inductively coupled plasma in the reactor chamber 101.
[0025] The reactor chamber 101 has a process volume 103 defined by
a cylindrical side wall 105 and a flat ceiling 110. A substrate
support pedestal 115 is disposed within the reactor chamber 101,
oriented in facing relationship to the flat ceiling 110 and
centered on the chamber axis of symmetry. The substrate support
pedestal 115 is configured to support a substrate 106 thereon. The
substrate support pedestal 115 comprises a supporting body 117
configured to receive and support the substrate 106 during process.
In one embodiment, the substrate support pedestal 115 has an edge
surface 118 circumscribing the substrate 106. The relative height
between the edge surface 118 and the substrate 106 is configured to
adjust processing results near the edge of the substrate 106.
[0026] A plurality of supporting pins 116 are movably disposed on
the substrate support pedestal 115 and are configured to facilitate
substrate transporting. A vacuum pump 120 cooperates with a vacuum
port 121 of the reactor chamber 101. A slit valve port 104 is
formed on the cylindrical side wall 105 allowing transporting of
substrates in and out of the process volume 103.
[0027] A process gas supply 125 furnishes process gas into the
process volume 103 through a gas inlet 130. The gas inlet 130 may
be centered on the flat ceiling 110 and has a plurality of gas
injection ports directing gas to different regions of the process
volume 103. In one embodiment, the gas inlet 130 may be configured
to supply individually adjustable flow of process gas to different
regions of the process volume 103 to achieve desired distribution
of process gas within the process volume 103.
[0028] The antenna assembly 102 comprises a cylindrical side wall
126 disposed on the flat ceiling 110 of the reactor chamber. A coil
mounting plate 127 is movably disposed on the side wall 126. The
side wall 126, the coil mounting plate 127, and the flat ceiling
110 generally define a coil volume 135. A plurality of coil hangers
132 extend from the coil mounting plate 127 in the coil volume 135.
The plurality of coil hangers 132 are configured to position one or
more coil antennas in the coil volume 135.
[0029] In one embodiment, an inner coil 131 and an outer coil 129
are arranged in the coil volume 135 to maintain a uniform plasma
ion density across the entire substrate surface during process. In
one embodiment, the inner coil 131 has a diameter of about 5 inches
and the outer coil 129 has a diameter of about 20 inches. Detailed
description of different designs of coil antennas may be found in
U.S. Pat. No. 6,685,798, entitled "Plasma Reactor Having a
Symmetric Parallel Conductor Coil Antenna", which is incorporated
herein by reference.
[0030] Each of the inner coil 131 and the outer coil 129 may be a
solenoidal multi-conductor interleaved coil antenna that defines a
vertical right circular cylinder or imaginary cylindrical surface
or locus whose axis of symmetry substantially coincides with that
of the reactor chamber 101. It is desirable to have axis of the
inner coil 131 and outer coil 129 to coincide with the axis of the
axis of symmetry of the substrate 106 to be processed in the
reactor chamber 101. However, the alignment among the inner coil
131, the outer coil 129, the reactor chamber 101, and the substrate
106 is susceptible to errors causing skews. The coil mounting plate
127 is movably positioned on the side walls 126 so that the inner
coil 131 and the outer coil 129 may be tilted relative to the
reactor chamber 101, together or independently. In one embodiment,
the coil mounting plate 127 may be adjusted rotating a tilt ring
128 positioned between the coil mounting plate 127 and the side
wall 126. The tilt ring 128 has a variable thickness which enables
a tilted mounting of the coil mounting plate 127.
[0031] The plasma reactor 100 further comprises a power assembly
134 configured to provide power supply to the inner coil 131 and
the outer coil 129. The power assembly 134 generally comprises RF
power supplies and matching networks. In one embodiment, the power
assembly 134 may be positioned above the coil mounting plate
127.
[0032] More detailed description of the plasma reactor 100 may be
found in U.S. patent application Ser. No. 11/960,111 (Attorney
Docket No. 12087), filed Dec. 19, 2007, entitled "Apparatus and
Method for Processing a Substrate Using Inductively Coupled Plasma
Technology", which is incorporated herein by reference.
[0033] FIG. 3 schematically illustrates a partial sectional side
view of a plasma reactor 400 having an injection assembly in
accordance with one embodiment of the present invention.
[0034] The plasma reactor 400 may be similar to the plasma reactor
100 of FIG. 2. The plasma reactor 400 has a process volume 403
defined by a sidewall 401, a supporting pedestal 402, and a lid
405. In one embodiment, a supporting ring 404 may be coupled
between the sidewall 401 and the lid 405. In one embodiment, the
process volume 403 may be substantially cylindrical and configured
to process circular substrates therein.
[0035] A gas supply assembly 410 is in fluid communication with the
process volume 403 and is at least partially disposed in the
process volume 403. The gas supply assembly is configured to supply
a processing gas from a gas source 416 to the process volume 403.
During process, a substrate 406 is disposed on the supporting
pedestal 402 and exposing a top surface 406a to the processing gas
in process volume 403. The gas supply assembly 410 is configured to
supply the processing gas to the process volume 403 in a desired
distribution, for example, a uniform distribution. In one
embodiment, the gas supply assembly 410 is configured to achieve a
desired distribution by injecting a process gas to at least two
process zones, and adjusting ratio of flow rates among different
process zones.
[0036] The gas supply assembly 410 comprises a nozzle 412 having a
cylindrical shape. The nozzle 412 is partially disposed in the
process volume 403 through an aperture 405a formed near a center of
the lid 405. The nozzle 412 may have a plurality of injection ports
configured to directing gas flow toward different regions of the
process volume 403.
[0037] The nozzle 412 has a plurality of central injection ports
422 configured to direct the process gas toward a central region of
the process volume 403. In one embodiment, the plurality of central
injection ports 422 are channels with openings perpendicular to the
substrate 406 and are configured to inject a flow along directions
shown by arrows 424.
[0038] The nozzle 412 has a plurality of outer injection ports 421
configured to direct the process gas toward an outer region of the
process volume 403. In one embodiment, the plurality of outer
injection ports 421 are channels with openings parallel to the
substrate 406 around the perimeter of the nozzle 412 and are
configured to inject a flow along directions shown by arrows
425.
[0039] The gas supply assembly 410 further comprises a feed plate
411 coupled to the nozzle 412. The feed plate 411 is configured to
receive two or more input flows and direct the input flows to the
nozzle 412.
[0040] FIGS. 4A-4B schematically illustrate sectional views of the
nozzle 412 and the feed plate 411. Referring to FIG. 4A, the feed
plate 411 has two receiving channels 413a, 414a configured to
connect to input flow. The receiving channel 414a opens to an inner
passage 419, which is a recess formed near a center of the feed
plate 411. The receiving channel 413a opens to an outer passage
420. The outer passage 420 is a circular recess surrounding the
inner passage 419.
[0041] Referring to FIG. 4B, when the feed plate 411 is coupled to
the nozzle 412, the inner passage 419 is in fluid communication
with a central recess 423 of the nozzle 412. The central recess 423
is connected to the plurality of central injection ports 422.
Therefore, the feed plate 411 and the nozzle 412 form a passage
that delivers fluid coming from the receiving channel 413a to a
central region of the process volume 403.
[0042] Similarly, the outer passage 420 is in fluid communication
the plurality of outer injection ports 421. Therefore, the feed
plate 411 and the nozzle 412 form a passage that delivers fluid
coming from the receiving channel 414a to an outer region of the
process volume 403.
[0043] In one embodiment, there are eight outer injection ports 421
evenly distributed around the nozzle 412 and seven central
injection ports 422 formed on a bottom of the nozzle 412. However,
other configurations of the injection ports are contemplated
depending on process requirement.
[0044] The nozzle 412 and feed plate 411 may be fabricated from
material suitable for chemistry and temperature requirement of
processes performed in the plasma reactor 400. In one embodiment,
the nozzle 412 may be fabricated from quartz. The lid 405 may also
be fabricated from quartz. In one embodiment, the feed plate 411
may be fabricated from ceramic.
[0045] Referring back to FIG. 3, the nozzle 412 and the feed plate
411 may be secured together by an upper clamp 418 and a lower clamp
417.
[0046] The gas supply assembly 410 further comprises a flow control
unit 415. The flow control unit 415 may have an input line 427
connected to the gas source 416, and two output lines 413, 414
connected to the feed plate 411. The flow control unit 415 may
comprise an adjustable splitter configured to split an incoming
flow from the input line 427 to the outputs 413, 414 at a variable
ratio. The flow control unit 415 may be also control the total flow
rate flown to the process volume 403. In one embodiment, the flow
control unit 415 may split the incoming flow according to a control
signal from a system controller 426 and may adjust a total flow
rate according to control signals from the system controller
426.
[0047] During processing, the gas source 416 provides a process gas
to the input line 427 of the flow control unit 415. The flow
control unit 415 then directs the incoming gas to either one or
both of the output lines 413, 414 according to the process
requirements, for example in the form of control signals from the
system controller 426. The process gas from the output lines 413,
414 then enter to passages formed in the feed plate 411 and the
nozzle 412. The process gas is then injected by the nozzle 412 to
different regions of the process volume 403 and to come in contact
with the substrate 406. Typically, the process gas flows from the
center of the process volume 403 where the nozzle 412 is disposed
to an edge of the process volume 403 and exists the process volume
403 with assistance from a pumping system 408.
[0048] The distribution of the process gas in the process volume
403, thus, degrees of exposure of surface areas of the substrate
406 may be controlled using the gas supply assembly 410. At least
three methods may be used individually or combined to achieve a
desired gas distribution. First, direction, number, and dimension
of the injection ports of the nozzle 412 may be adjusted to direct
the process gas towards different regions of the process volume
403. Second, a ratio of the flow rates among different regions may
be adjusted to achieve a desired distribution. Third, a total flow
rate may be adjusted to achieve a desired distribution.
[0049] FIGS. 5A-5C are charts showing results of a nitridation
process using a plasma reactor having an injection assembly in
accordance with one embodiment of the present invention. The
results in FIGS. 5A-5C demonstrate different gas distribution in a
process chamber during a nitridation process as a result of flow
adjustments using a gas supply assembly similar to the gas supply
assembly 410 of FIG. 3.
[0050] The nitridation process is generally performed to silicon
dioxide gate dielectric film formed on a substrate. The substrate
is positioned in the plasma reactor, for example, the plasma
reactor 100 of FIG. 2. Nitrogen gas is flown to the plasma chamber
and a plasma is struck by applying RF power to a coil assembly,
such as the coil assemblies 129, 131 of FIG. 2, while the nitrogen
flows continuously. The plasma ionizes the nitrogen and the ionized
nitrogen then diffuses into the silicon dioxide gate dielectric
film.
[0051] FIG. 5A shows results from four processes of nitrogen dosage
in a nitridation process when the processing gas is only supplied
towards a central region of the process volume. During each
process, the flow control unit 415 directs 100% of the incoming
flow to the output line 414 which leads to the plurality of central
injection ports 422 and all of the process gas enters the process
volume 403 along directions illustrated by arrows 424. While the
flow control unit 415 directs none of the incoming flow to the
output line 413 that leads to the plurality of outer injection
ports 421 and none of the process gas enters the process volume 403
along directions illustrated by arrows 425. The total flow rates
for the four processes are 100 sccm, 300 sccm, 500 sccm, and 700
sccm respectively. The change of flow rates can be accomplished by
using the flow control unit 415 also.
[0052] Results in FIG. 5A show that when the central region of the
substrate has more exposure to the process gas than the edge region
of the substrate when the process gas is supplied from the central
injection ports only. The degree of difference between the central
region and the edge region increases with the total flow rate.
[0053] FIG. 5B shows results from three processes of nitrogen
dosage in a nitridation process when the processing gas is only
supplied towards the edge region of the process volume. During each
process, the flow control unit 415 directs none of the incoming
flow to the output line 414 which leads to the plurality of central
injection ports 422 and none of the process gas enters the process
volume 403 along directions illustrated by arrows 424. While the
flow control unit 415 directs 100% of the incoming flow to the
output line 413 that leads to the plurality of outer injection
ports 421 and all of the process gas enters the process volume 403
along directions illustrated by arrows 425. The total flow rates
for the three processes are 100 sccm, 300 sccm, and 500 sccm
respectively. The change of flow rates can also be accomplished by
using the flow control unit 415.
[0054] Results in FIG. 5B show that the central region of the
substrate has less exposure to the process gas than the edge region
of the substrate when the process gas is supplied from the edge
injection ports only. The degree of difference between the central
region and the edge region increases with the total flow rate.
[0055] FIG. 5C shows results from seven processes of nitrogen
dosage in a nitridation process when the processing gas is supplied
towards both the edge region and the central region of the process
volume. The total flow rates for the seven processes remain at 400
sccm but the ratio of the flow rate changes.
[0056] Results in FIG. 5C show the degree of gas distribution
difference between the central region and the edge region may be
adjustable by adjusting the ratio of flow rates for different
regions.
[0057] FIGS. 5A-5C demonstrate that a desired gas distribution, for
example uniform gas distribution, may be achieved by adjusting
ratios of flow rates for injected gases towards different regions
and the resulting ratios may be different when the total flow rate
changes. Therefore, a desired gas distribution may be achieved by
adjusting ratio, total flow rate, or both.
[0058] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *