U.S. patent application number 10/336241 was filed with the patent office on 2004-07-08 for gas nozzle for substrate processing chamber.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Murugesh, Laxman.
Application Number | 20040129210 10/336241 |
Document ID | / |
Family ID | 32680971 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040129210 |
Kind Code |
A1 |
Murugesh, Laxman |
July 8, 2004 |
Gas nozzle for substrate processing chamber
Abstract
A gas delivery nozzle for a substrate fabrication apparatus has
a gas delivery tube. The gas delivery tube encloses a gas channel
having an asymmetrically tapered aperture. The asymmetrically
tapered aperture is defined by (i) a lower lip that projects
upwardly into the gas channel to partially block the gas channel
and (ii) a upper brim that projects downwardly into the gas channel
and overhangs the lower lip.
Inventors: |
Murugesh, Laxman; (San
Ramon, CA) |
Correspondence
Address: |
Applied Materials Inc
Patent Department
P.O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
32680971 |
Appl. No.: |
10/336241 |
Filed: |
January 3, 2003 |
Current U.S.
Class: |
118/715 |
Current CPC
Class: |
C23C 16/45504 20130101;
C23C 16/455 20130101; C23C 16/45563 20130101; H01L 21/67017
20130101 |
Class at
Publication: |
118/715 |
International
Class: |
C23F 001/00 |
Claims
We claim:
1. A gas delivery nozzle for a substrate fabrication apparatus, the
gas delivery nozzle comprising: a gas delivery tube enclosing a gas
channel having an asymmetrically tapered aperture defined by: (i) a
lower lip that projects upwardly into the gas channel to partially
block the gas channel, and (ii) a upper brim that projects
downwardly into the gas channel and overhangs the lower lip.
2. The gas delivery nozzle of claim 1 wherein the lower lip
comprises an external slanted face that is at an angle of at least
about 5.degree. in relation to a central axis of the gas delivery
tube along the gas channel.
3. The gas delivery nozzle of claim 2 wherein the external slanted
face is at an angle of less than 90.degree..
4. The gas delivery nozzle of claim 1 wherein the upper brim
extends beyond the lower lip by at least about 1 mm.
5. The gas delivery nozzle of claim 1 wherein the asymmetrically
tapered aperture comprises a center that is offset below the
central axis of the gas delivery tube.
6. The gas delivery nozzle of claim 1 wherein the lower lip
comprises a protuberance having a crescent shape.
7. A substrate fabrication apparatus comprising: a chamber having a
substrate support to support a substrate in the chamber; a gas
distributor to introduce a process gas into the chamber, the gas
distributor comprising a gas delivery nozzle in the chamber, the
gas delivery nozzle comprising a gas delivery tube that encloses a
gas channel having an asymmetrically tapered aperture, the
asymmetrically tapered aperture defined by: (i) a lower lip that
projects upwardly into the gas channel to partially block the gas
channel, and (ii) a upper brim that projects downwardly into the
gas channel and overhangs the lower lip; a gas energizer to
energize the process gas to process the substrate; and a gas
exhaust to exhaust the process gas from the chamber.
8. The apparatus of claim 7 wherein the lower lip comprises an
external slanted face that is at an angle of at least about
5.degree. in relation to a central axis of the gas delivery tube
along the gas channel.
9. The apparatus of claim 8 wherein the external slanted face is at
an angle of less than 90.degree..
10. The apparatus of claim 7 wherein the upper brim extends beyond
the lower lip by at least about 1 mm.
11. The apparatus of claim 7 wherein the asymmetrically tapered
aperture comprises a center that is offset below the central axis
of the gas delivery tube.
12. The apparatus of claim 7 wherein the lower lip comprises a
protuberance having a crescent shape.
Description
BACKGROUND
[0001] In the fabrication of electronic circuits, such as
integrated circuits and displays, materials such as semiconductor,
dielectric and conductor materials are deposited and patterned on a
substrate 5. Some of these materials are deposited by chemical
vapor deposition (CVD) or physical vapor deposition (PVD)
processes, and others may be formed by oxidation or nitridation of
substrate materials. For example, in chemical vapor deposition
processes, a deposition gas is introduced into a chamber 20 and
energized by heat and/or RF energy to deposit a film on the
substrate. In physical vapor deposition, a target is sputtered to
deposit a layer of the target material on the substrate 5. In
etching processes, a patterned mask, comprising a photoresist or
hard mask material, is formed on the substrate surface 15 by
lithography and subsequent etching, and portions of the substrate
surface 15 that are exposed between the mask features are etched by
an energized gas, such as a halogen or oxygen containing gas. Such
deposition and etching processes, and additional planarization
processes, are conducted in a sequence to process the substrate 5
to fabricate integrated circuits and other electronic devices.
[0002] In one type of conventional process chamber, a gas delivery
tube 10 is used to introduce process gas from a gas supply into the
chamber 20, as illustrated in FIG. 1 (Prior Art). The gas delivery
tube 10 typically comprises a gas outlet 25 in the chamber 20 that
injects the process gas 40 (which may be a single gas or a premixed
mixture of gases) into a process zone of the chamber 20. The gas
delivery tube 10, passes through the sidewall 30 of the chamber 20
and injects gas laterally into the chamber 20 from a gas outlet 25
located at a periphery of the substrate 5. However, as shown in the
figure, a portion of the injected gas 40 travels to a ceiling 35 of
the chamber 20 and forms undesirable deposits 18 on the ceiling
surface. These deposits 18 have to be cleaned by shutting down the
chamber 20 and manually scraping off the deposits or using plasma
cleaning gas processes, both of which increase chamber down time,
which is undesirable in circuit fabrication.
[0003] The laterally injected process gas may also fail to reach
the central portion of the substrate 5 in the same concentration
levels as that reaching the edge of the substrate 5. The gas
delivery tube 10 ejects the process gas 40 in an angular density
distribution that often does not cover the substrate surface 15
with sufficient uniformity. This can result in little or no
deposition at the center of the substrate surface 15. Thus, a
second gas delivery tube 45 is sometimes provided above the center
of the substrate 5 to direct process gas 40 towards the central
substrate portion. However, the additional gas delivery tube 45
increases the costs of the chamber 20 because the ceiling 35 to
pass the gas delivery tube 45 therethrough, especially when the
ceiling 35 that has to be drilled through is made of a ceramic
material. Also, the gas delivery tubes 10, 45 can block the line of
sight of interferometric endpoint detection systems (not shown)
located above the chamber ceiling 35. Additionally, the overhead
gas delivery tube 45 may interfere with the transmission of RF
energy that may be applied from an induction antenna 50 above the
ceiling 35.
[0004] Thus, it is desirable to have a gas delivery tube that
minimizes deposition on the ceiling surface of the chamber 20,
provides good uniformity of deposition across the substrate surface
15, and does not excessively increase the cost of fabricating the
chamber 20.
SUMMARY
[0005] A gas delivery nozzle for a substrate fabrication apparatus
comprises a gas delivery tube. The gas delivery tube encloses a gas
channel having an asymmetrically tapered aperture. The
asymmetrically tapered aperture is defined by (i) a lower lip that
projects upwardly into the gas channel to partially block the gas
channel and (ii) a upper brim that projects downwardly into the gas
channel and overhangs the lower lip.
[0006] A substrate fabrication apparatus comprises a chamber having
a substrate support to support a substrate in the chamber. A gas
distributor introduces a process gas into the chamber. The gas
distributor comprises a gas delivery nozzle in the chamber, the gas
delivery nozzle comprising a gas delivery tube that encloses a gas
channel having an asymmetrically tapered aperture. The
asymmetrically tapered aperture is defined by (i) a lower lip that
projects upwardly into the gas channel to partially block the gas
channel and (ii) a upper brim that projects downwardly into the gas
channel and overhangs the lower lip. A gas energizer energizes the
process gas to process the substrate. A gas exhaust exhausts the
process gas from the chamber.
DRAWINGS
[0007] FIG. 1 (Prior Art) is a partial sectional side view of
conventional gas delivery tubes in a process chamber, showing an
undesirable gas flow pattern provided by the gas delivery tubes;
and
[0008] FIG. 2 is a partial sectional side view of a gas delivery
tube according to the present invention in an embodiment of a
process chamber of a substrate fabrication apparatus, showing the
desirable gas flow pattern provided by the gas delivery tube.
DESCRIPTION
[0009] A substrate processing chamber 140 of a substrate
fabrication apparatus 200 comprises an improved gas delivery nozzle
110 to uniformly and efficiently distribute process gas 102 across
a substrate 145 while minimizing formation of excessive residue
deposits on the ceiling 150 of the chamber 140, as illustrated in
FIG. 2. The exemplary embodiment of the substrate fabrication
apparatus 200 illustrated in the figure, comprises a substrate
support 142 to support the substrate in the chamber 140. A gas
distributor 226 comprises a process gas supply 210 that is provided
to supply the process gas 102 for the processing of the substrate
145 into the chamber 140. A flow valve 220 adjusts the flow of
process gas from the gas supply 210 into the chamber 140. A gas
energizer 228 comprises an antenna 230 or electrode that applies a
fluctuating electromagnetic field to the process gas 102 to
energize the process gas and thereby process the substrate 145. An
energizer power supply 240 supplies an alternating current to the
antenna 230 or electrode to generate the fluctuating
electromagnetic field, and a controller 250 is provided to regulate
the flow of the process gas into chamber 140 and to control
energizing of the process gas 102. A gas exhaust (not seen)
exhausts the process gas from the chamber 140.
[0010] The gas delivery nozzle 110 may be positioned to the side of
the substrate 145 to aim the process gas flow across and over the
surface 155 of the substrate 145. The gas delivery nozzle 110
extends from the sidewall 180 to direct the process gas laterally
toward the substrate 145.
[0011] The gas delivery nozzle 110 comprises a gas delivery tube
165 that encloses a gas channel 120 through which the process gas
102 is passed. The gas channel 120 terminates in an asymmetrically
tapered aperture 130, as shown in the figure. The gas delivery tube
165 has a central axis 125, and an asymmetrically tapered aperture
130 is provided at the end of the tube 165 to define an opening
that is offset from, and radially asymmetric about, the central
axis 125 of the gas delivery tube 165. The asymmetrically tapered
aperture 130 ejects the process gas asymmetrically away from the
ceiling 150 of the chamber 140, and toward the substrate surface
155, in a spray pattern that reduces deposition of material on the
ceiling or etching of the ceiling 150 and also improves uniformity
of gas distribution over the substrate surface 155.
[0012] The asymmetrically tapered aperture 130 comprises a lower
lip 170 that projects upwardly into the gas channel 120 to
partially block the gas channel 120. For example, the lower lip 170
may comprise a protuberance that extends from the tube wall and
into the gas channel. The protuberance can have a crescent shape
that defines the bottom edge of the tapered aperture 130. The lower
lip 170 upwardly guides lower laminae 121 of the gas stream,
increasing the velocity, and decreasing the pressure, of these
lower laminae 121 to guide the gas stream away from the chamber
ceiling 150, as shown in the figure. The upper and lower laminae
122, 121 of the gas flow in the gas channel 120 are forced through
the main portion of the channel at substantially uniform pressure
and velocity. As the lower laminae 121 approach the asymmetrically
tapered aperture 130, they are obstructed and guided upwardly by
the lower lip 170. The lower lip 170 may be a uniformly sloped
protuberance, as shown in the figure, or alternatively the
protuberance may be curved to more gradually alter the velocity of
the obstructed process gas 102.
[0013] The asymmetrically tapered aperture 130 further comprises an
upper brim 175 that projects downwardly into the gas channel 120
and overhangs the lower lip 170. For example, in one embodiment the
upper brim extends beyond the lower lip by at least about 1 mm. As
the upper and lower laminae 122, 121 approach the ejection point,
the lower laminae 121 impinge on the upper laminae 122 from below
with high velocity, causing the process gas to be redirected into
the projecting upper brim 175 overhanging the lower lip 170 at high
velocity. The projecting upper brim 175 causes the process gas to
be reflected downwardly, away from the chamber ceiling 150 and
towards the substrate surface 155, thus reducing problematic
deposition onto, or etching of, the chamber ceiling 150. The upper
brim can also comprise a protuberance that extends downwardly from
the tube wall into the volume of the gas channel 120. The
protuberance can comprise a gentle hump with a raised portion in
the middle and depressions in the side. This causes the upper
laminae 122 to be directed downwardly toward the periphery of the
substrate. As a result of the combination of the upper laminae,
which more efficiently cover the substrate periphery, and the lower
laminae, which more efficiently cover the central portion of the
substrate, the gas delivery nozzle 110 generates a more uniform
distribution of process gas across the substrate surface.
[0014] The asymmetric design of the tapered outlet 130 also allows
the tapered outlet 130 to direct the process gas substantially
towards the substrate surface 165 with a desirable angular density
distribution to cover the substrate surface 165 substantially
uniformly. As the process gas exits the asymmetrically tapered
aperture 130, the lower lip 170 asymmetrically obstructs the flow
of the process gas, inwardly redirecting the lower laminae in the
outer region of the gas flow to increase the gas density in the
center of the gas flow stream, as shown in FIG. 2. The
asymmetrically tapered aperture 130 also imparts an asymmetry to
the density distribution of the gas flow stream, which compensates
for the asymmetrical positioning of the gas delivery nozzle 110 to
one side of the substrate 145. The asymmetrically tapered aperture
130 concentrates the gas that is projected toward the central
region 185 above the center of the substrate surface 155, resulting
in improved exposure of the central portion of the substrate
surface 155, and thus substantially uniform coverage of the
substrate 145. In one embodiment, the asymmetrically tapered
aperture 130 is shaped to deliver the majority of the process gas
below the central axis 125 of the gas delivery tube 165. In
contrast, the conventional gas nozzles, as illustrated in FIG. 1
(Prior Art), cause the process gas to bloom outwardly and
substantially symmetrically upon ejection, resulting in a centrally
deficient portion of the stream that insufficiently exposes the
central portion of the substrate surface 155. The improved gas
delivery nozzle 110 ejects the process gas from the nozzle 115
toward the substrate 145 in a spray pattern that is radially
asymmetric about the central axis 125 of the gas delivery nozzle
110, preventing the process gas from detrimentally and wastefully
streaming towards the ceiling 150 of the process chamber 140, and
also improving the uniformity of coverage of the substrate surface
155.
[0015] The lower lip 170 of the asymmetrically tapered aperture 130
can also have a slanted external face 135, as shown in FIG. 2.
After the process gas 102 is ejected from the asymmetrically
tapered aperture 130 and is then decelerated, a region of high
pressure forms in the process gas adjacent to the external slanted
face 135 of the lower lip 170. The pressurized gas in this region
applies a force to the lower lip 170, and the lower lip 170 applies
an equal and opposite force to the gas in the high pressure region
in a direction normal to, and away from, the lower lip 170,
directing the process gas at a downward angle toward the substrate
145. The external slanted face 135 of the lower lip 170 serves as a
springboard for the process gas after the process gas is projected
from the opening 190 of the asymmetrically tapered aperture 130.
For example, the external slanted face 135 of the asymmetrically
tapered aperture 130 may be at an angle of less than 90.degree. in
relation to the central axis 125 to achieve a desirable angular
distribution of mass flow. The external slanted face 135 may even
be at an angle of at least about 5.degree. in relation to the
central axis 125 to achieve a more desirable angular
distribution.
[0016] The gas delivery nozzle 110 is adapted to eject the process
gas from the asymmetrically tapered aperture 130 toward the
substrate 145 in a desirable spray pattern that prevents the
process gas from detrimentally and wastefully streaming towards the
ceiling 150 of the chamber 140, and improves the uniformity of
coverage of the substrate surface 155. This gas nozzle design also
significantly reduces the formation of process deposits on the
ceiling 150 of the chamber 140. As a result, the chamber 140 could
be cleaned less often and operated for longer hours between
cleaning cycles.
* * * * *