U.S. patent application number 15/658911 was filed with the patent office on 2019-01-31 for showerhead tilt mechanism.
This patent application is currently assigned to LAM RESEARCH CORPORATION. The applicant listed for this patent is LAM RESEARCH CORPORATION. Invention is credited to Dave Kamp, Bin Luo, Damien Slevin, Timothy Scott Thomas.
Application Number | 20190032214 15/658911 |
Document ID | / |
Family ID | 65032046 |
Filed Date | 2019-01-31 |
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United States Patent
Application |
20190032214 |
Kind Code |
A1 |
Luo; Bin ; et al. |
January 31, 2019 |
SHOWERHEAD TILT MECHANISM
Abstract
A showerhead tilt adjustment mechanism is provided which
supports a showerhead module in a top plate of a semiconductor
substrate processing apparatus, the showerhead tilt adjustment
mechanism including a differential screw which provides coarse and
fine adjustments to adjust gap/tilt/planarization of a faceplate of
the showerhead module with respect to an upper surface of a
substrate pedestal module adjacent the faceplate in the
semiconductor substrate processing apparatus.
Inventors: |
Luo; Bin; (Beaverton,
OR) ; Thomas; Timothy Scott; (Wilsonville, OR)
; Slevin; Damien; (Salem, OR) ; Kamp; Dave;
(Wilsonville, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LAM RESEARCH CORPORATION |
Fremont |
CA |
US |
|
|
Assignee: |
LAM RESEARCH CORPORATION
Fremont
CA
|
Family ID: |
65032046 |
Appl. No.: |
15/658911 |
Filed: |
July 25, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/4409 20130101;
C23C 16/458 20130101; H01L 21/02274 20130101; C23C 16/505 20130101;
C23C 16/50 20130101; C23C 16/45565 20130101 |
International
Class: |
C23C 16/455 20060101
C23C016/455; C23C 16/458 20060101 C23C016/458; C23C 16/50 20060101
C23C016/50 |
Claims
1. A semiconductor substrate processing apparatus for processing
semiconductor substrates comprising: a chemical isolation chamber
in which individual semiconductor substrates are processed, the
chemical isolation chamber including a top plate forming an upper
wall of the chemical isolation chamber; a process gas source in
fluid communication with the chemical isolation chamber for
supplying at least one process gas into the chemical isolation
chamber; a showerhead module which delivers the process gas from
the process gas source to a processing zone of the processing
apparatus wherein the individual semiconductor substrates are
processed, the showerhead module including a base attached to a
lower end of a stem wherein a faceplate having gas passages
therethrough forms a lower surface of the base and the stem extends
through a vertically extending bore in the top plate; a substrate
pedestal module configured to support the semiconductor substrate
in the processing zone below the faceplate during processing of the
substrate; a bellows assembly supporting the showerhead module, the
bellows assembly including a collar, a bellows and a leveling
plate, the collar having a central opening aligned with the bore in
the top plate, the bellows surrounding the central opening in the
collar and having a lower end attached to an upper surface of the
collar and an upper end attached to a lower surface of the leveling
plate, the leveling plate having a central opening aligned with the
bore in the top plate; at least one showerhead tilt adjustment
mechanism operable to adjust tilting of the faceplate of the
showerhead module with respect to an upper surface of the substrate
pedestal module adjacent the faceplate, wherein the showerhead tilt
adjustment mechanism comprises a lock screw, a hollow screw, a lock
plate, and a lock nut, the hollow screw having a first threaded
section on an outer surface thereof and a second threaded section
on the outer surface, the first threaded section having a thread
pitch which is different than a thread pitch of the second threaded
section, the first threaded section engaged with an internally
threaded bore of the leveling plate, the second threaded section
engaged with an internal thread of the locking nut, the lock screw
having a lower external threaded section engaged with a threaded
bore in the collar and an upper screw head engaging a shoulder of
an upper socket in the hollow screw, and the lock plate movable
from a first position at which the lock nut rotates with the hollow
screw to a second position at which the lock nut cannot rotate, the
showerhead tilt adjustment mechanism providing coarse adjustment
when the lock plate is in the first position and fine adjustment
when the lock plate is in the second position.
2. The semiconductor substrate processing apparatus of claim 1,
wherein the at least one showerhead tilt adjustment mechanism
comprises three showerhead tilt adjustment mechanisms spaced
outwardly of the bellows at locations 120.degree. apart.
3. The semiconductor substrate processing apparatus of claim 1,
wherein the lock plate is movable in a radial direction between the
first and second positions.
4. The semiconductor substrate processing apparatus of claim 1,
wherein the leveling plate includes an upwardly extending tubular
section wherein an inner surface of the tubular section includes
the threaded bore.
5. The semiconductor substrate processing apparatus of claim 1,
wherein the lock plate includes a handle at an outer end thereof
extending outwardly of the collar, a wide slot at an inner end
thereof which can engage the lock nut, and a narrow slot extending
outward from the wide slot, and a lock plate screw extending
through the narrow slot and threaded into the collar, the lock
plate screw having a screw head which can be tightened against the
lock plate to prevent movement of the lock plate.
6. The semiconductor substrate processing apparatus of claim 1,
wherein the showerhead tilt adjustment mechanism can provide a
coarse gap adjustment of about 0.02 to about 0.04 inch per full
rotation of the hollow screw when the lock plate is in the first
position and a fine gap adjustment of about 0.002 to about 0.004
inch per full rotation of the hollow screw when the lock plate is
in the second position.
7. A showerhead tilt adjustment mechanism configured to provide
coarse and fine gap adjustments of a showerhead module supported in
a top plate of a semiconductor substrate processing apparatus by a
bellows assembly, wherein the showerhead tilt adjustment mechanism
comprises: a lock screw, a hollow screw, a lock plate, and a lock
nut; the hollow screw having a first threaded section on an outer
surface thereof and a second threaded section on the outer surface,
the first threaded section having a thread pitch which is different
than a thread pitch of the second threaded section, the first
threaded section configured to engage with an internally threaded
bore of a leveling plate of the bellows assembly, the second
threaded section engaged with an internal thread of the locking
nut; the lock screw having a lower external threaded section
configured to engage with a threaded bore in a collar of the
bellows assembly and an upper screw head engaging a shoulder of an
upper socket in the hollow screw; and the lock plate movable from a
first position at which the lock nut rotates with the hollow screw
to a second position at which the lock nut cannot rotate, the
showerhead tilt adjustment mechanism providing coarse adjustment
when the lock plate is in the first position and fine adjustment
when the lock plate is in the second position.
8. The showerhead tilt adjustment mechanism of claim 7, wherein the
first and second threaded sections on the hollow screw have the
same orientation.
9. The showerhead tilt adjustment mechanism of claim 7, wherein the
lock plate includes a handle at an outer end thereof, a wide slot
at an inner end thereof which can engage the lock nut, and a narrow
slot extending outward from the wide slot, the narrow slot
configured to receive a lock plate screw threaded into the collar,
the lock plate screw having a screw head which can be tightened
against the lock plate to prevent movement of the lock plate.
10. The showerhead tilt adjustment mechanism of claim 7, wherein
the showerhead tilt adjustment mechanism can provide a coarse gap
adjustment of about 0.02 to about 0.04 inch per full rotation of
the hollow screw when the lock plate is in the first position and a
fine gap adjustment of about 0.002 to about 0.004 inch per full
rotation of the hollow screw when the lock plate is in the second
position.
11. A showerhead module which delivers process gas from a process
gas source to a processing zone of a semiconductor substrate
processing apparatus wherein individual semiconductor substrates
are processed, the showerhead module comprising: a base attached to
a lower end of a stem wherein a faceplate having gas passages
therethrough forms a lower surface of the base and the stem is
configured to extend through a vertically extending bore in a top
plate of the processing apparatus; a bellows assembly supporting
the showerhead module, the bellows assembly including a collar, a
bellows and a leveling plate, the collar having a central opening
aligned with the bore in the top plate, the bellows surrounding the
central opening in the collar and having a lower end attached to an
upper surface of the collar and an upper end attached to a lower
surface of the leveling plate, the leveling plate having a central
opening aligned with the bore in the top plate; at least one
showerhead tilt adjustment mechanism operable to adjust tilting of
the faceplate of the showerhead module, wherein the showerhead tilt
adjustment mechanism comprises a lock screw, a hollow screw, a lock
plate, and a lock nut, the hollow screw having a first threaded
section on an outer surface thereof and a second threaded section
on the outer surface, the first threaded section having a thread
pitch which is different than a thread pitch of the second threaded
section, the first threaded section engaged with an internally
threaded bore of the leveling plate, the second threaded section
engaged with an internal thread of the locking nut, the lock screw
having a lower external threaded section engaged with a threaded
bore in the collar and an upper screw head engaging a shoulder of
an upper socket in the hollow screw, and the lock plate movable
from a first position at which the lock nut rotates with the hollow
screw to a second position at which the lock nut cannot rotate, the
showerhead tilt adjustment mechanism providing coarse adjustment
when the lock plate is in the first position and fine adjustment
when the lock plate is in the second position.
12. The showerhead module of claim 11, wherein the at least one
showerhead tilt adjustment mechanism comprises three showerhead
tilt adjustment mechanisms spaced outwardly of the bellows at
locations 120.degree. apart.
13. The showerhead module of claim 11, wherein the lock plate is
movable in a radial direction between the first and second
positions.
14. The showerhead module of claim 11, wherein the leveling plate
includes an upwardly extending tubular section wherein an inner
surface of the tubular section includes the threaded bore.
15. The showerhead module of claim 11, wherein the lock plate
includes a handle at an outer end thereof extending outwardly of
the collar, a wide slot at an inner end thereof which can engage
the lock nut, and a narrow slot extending outward from the wide
slot, and a lock plate screw extending through the narrow slot and
threaded into the collar, the lock plate screw having a screw head
which can be tightened against the lock plate to prevent movement
of the lock plate.
16. The showerhead module of claim 15, wherein the showerhead tilt
adjustment mechanism can provide a coarse gap adjustment of about
0.02 to about 0.04 inch per full rotation of the hollow screw when
the lock plate is in the first position and a fine gap adjustment
of about 0.002 to about 0.004 inch per full rotation of the hollow
screw when the lock plate is in the second position.
17. A method of controlling in-plane distortion (IPD) due to
showerhead tilt in a semiconductor substrate processing apparatus,
the method comprising: measuring IPD changes across a wafer
processed in a processing chamber of the semiconductor substrate
processing apparatus; adjusting tilt of a showerhead of the
semiconductor substrate processing apparatus using three showerhead
tilt adjustment mechanisms configured to provide coarse and fine
IPD adjustments wherein each of the showerhead tilt adjustment
mechanisms comprises a lock screw, a hollow screw, a lock plate and
a lock nut arranged to vary a gap between a movable part attached
to the showerhead and a fixed part in the processing chamber;
wherein the hollow screw has a first threaded section on an outer
surface thereof and a second threaded section on the outer surface,
the first threaded section having a thread pitch which is different
than a thread pitch of the second threaded section, the first
threaded section engaged with an internally threaded bore of the
movable part, and the second threaded section engaged with an
internal thread of the locking nut; the lock screw has a lower end
threaded into a bore in the fixed part and an upper screw head
engaging a shoulder of an upper socket in the hollow screw; and the
lock plate is movable from a first position at which the lock nut
rotates with the hollow screw to a second position at which the
lock nut cannot rotate, the showerhead tilt adjustment mechanism
providing coarse adjustment when the lock plate is in the first
position and fine adjustment when the lock plate is in the second
position.
18. The method of claim 17, comprising making a coarse adjustment
by positioning the lock plate of one of the showerhead tilt
adjustment mechanisms in the first position and rotating the hollow
screw to a first radial position, and making a fine adjustment by
moving the lock plate to the second position and rotating the
hollow screw to a second radial position at which the IPD is
reduced.
19. The method of claim 18, wherein a slot extends through a wall
of the socket, the method further comprising placing an indicator
cap having an upper alignment mark onto the hollow screw such that
a projection on the indicator cap fits within the slot, recording a
pre-adjustment angle of alignment mark, removing the indicator cap
and making the IPD adjustment, placing the indicator cap on the
hollow screw and recording a post-adjustment angle of the alignment
mark.
20. The method of claim 17, wherein the first and second threaded
sections have the same orientation and each of the showerhead tilt
adjustment mechanisms can provide a coarse gap adjustment of about
0.02 to about 0.04 inch per full rotation of the hollow screw when
the lock plate is in the first position and a fine gap adjustment
of about 0.002 to about 0.004 inch per full rotation of the hollow
screw when the lock plate is in the second position.
Description
FIELD OF INVENTION
[0001] This invention pertains to semiconductor substrate
processing apparatuses used for processing semiconductor
substrates, and may find particular use in performing chemical
vapor depositions of thin films.
BACKGROUND
[0002] Semiconductor substrate processing apparatuses are used to
process semiconductor substrates by techniques including, physical
vapor deposition (PVD), chemical vapor deposition (CVD), plasma
enhanced chemical vapor deposition (PECVD), atomic layer deposition
(ALD), plasma enhanced atomic layer deposition (PEALD), pulsed
deposition layer (PDL), molecular layer deposition (MLD), plasma
enhanced pulsed deposition layer (PEPDL) processing, etching, and
resist removal. One type of semiconductor substrate processing
apparatus used to process semiconductor substrates includes a
reaction chamber containing a showerhead module and a substrate
pedestal module which supports the semiconductor substrate in the
reaction chamber. The showerhead module delivers process gas into
the reactor chamber so that the semiconductor substrate may be
processed. In such chambers installation and removal of the
showerhead module can be time consuming, and further, non-uniform
film deposition (i.e. azimuthal variation) during substrate
processing can occur if a lower surface of the showerhead module is
not parallel to an upper surface of the substrate pedestal
module.
SUMMARY
[0003] Disclosed herein is a semiconductor substrate processing
apparatus for processing semiconductor substrates comprising (a) a
chemical isolation chamber in which individual semiconductor
substrates are processed, the chemical isolation chamber including
a top plate forming an upper wall of the chemical isolation
chamber, (b) a process gas source in fluid communication with the
chemical isolation chamber for supplying at least one process gas
into the chemical isolation chamber, (c) a showerhead module which
delivers the process gas from the process gas source to a
processing zone of the processing apparatus wherein the individual
semiconductor substrates are processed, the showerhead module
including a base attached to a lower end of a stem wherein a
faceplate having gas passages therethrough forms a lower surface of
the base and the stem extends through a vertically extending bore
in the top plate, (d) a substrate pedestal module configured to
support the semiconductor substrate in the processing zone below
the faceplate during processing of the substrate, (e) a bellows
assembly supporting the showerhead module, the bellows assembly
including a collar, a bellows and a leveling plate, the collar
having a central opening aligned with the bore in the top plate,
the bellows surrounding the central opening in the collar and
having a lower end attached to an upper surface of the collar and
an upper end attached to a lower surface of the leveling plate, the
leveling plate having a central opening aligned with the bore in
the top plate, and (f) at least one showerhead tilt adjustment
mechanism operable to adjust tilting of the faceplate of the
showerhead module with respect to an upper surface of the substrate
pedestal module adjacent the faceplate, wherein the showerhead tilt
adjustment mechanism comprises a lock screw, a hollow screw, a lock
plate, and a lock nut, the hollow screw having a first threaded
section on an outer surface thereof and a second threaded section
on the outer surface, the first threaded section having a thread
pitch which is different than a thread pitch of the second threaded
section, the first threaded section engaged with an internally
threaded bore of the leveling plate, the second threaded section
engaged with an internal thread of the locking nut, the lock screw
having a lower external threaded section engaged with a threaded
bore in the collar and an upper screw head engaging a shoulder of
an upper socket in the hollow screw, and the lock plate movable
from a first position at which the lock nut rotates with the hollow
screw to a second position at which the lock nut cannot rotate, the
showerhead tilt adjustment mechanism providing coarse adjustment
when the lock plate is in the first position and fine adjustment
when the lock plate is in the second position.
[0004] The at least one showerhead tilt adjustment mechanism
preferably comprises three showerhead tilt adjustment mechanisms
spaced outwardly of the bellows at locations 120.degree. apart. The
lock plate can be movable in a radial direction between the first
and second positions and/or the leveling plate can include an
upwardly extending tubular section wherein an inner surface of the
tubular section includes the threaded bore. The lock plate can
include a handle at an outer end thereof extending outwardly of the
collar, a wide slot at an inner end thereof which can engage the
lock nut, and a narrow slot extending outward from the wide slot,
and a lock plate screw extending through the narrow slot and
threaded into the collar, the lock plate screw having a screw head
which can be tightened against the lock plate to prevent movement
of the lock plate. In a preferred embodiment, the showerhead tilt
adjustment mechanism can provide a coarse gap adjustment of about
0.02 to about 0.04 inch per full rotation of the hollow screw when
the lock plate is in the first position and a fine gap adjustment
of about 0.002 to about 0.004 inch per full rotation of the hollow
screw when the lock plate is in the second position.
[0005] In an embodiment, a method of controlling in-plane
distortion (IPD) due to showerhead tilt in a semiconductor
substrate processing apparatus comprises (a) measuring IPD changes
across a wafer processed in a processing chamber of the
semiconductor substrate processing apparatus, (b) adjusting tilt of
a showerhead of the semiconductor substrate processing apparatus
using three showerhead tilt adjustment mechanisms configured to
provide coarse and fine IPD adjustments wherein each of the
showerhead tilt adjustment mechanisms comprises a lock screw, a
hollow screw, a lock plate and a lock nut arranged to vary a gap
between a movable part attached to the showerhead and a fixed part
in the processing chamber, (c) wherein the hollow screw has a first
threaded section on an outer surface thereof and a second threaded
section on the outer surface, the first threaded section having a
thread pitch which is different than a thread pitch of the second
threaded section, the first threaded section engaged with an
internally threaded bore of the movable part, and the second
threaded section engaged with an internal thread of the locking
nut, (d) the lock screw has a lower end threaded into a bore in the
fixed part and an upper screw head engaging a shoulder of an upper
socket in the hollow screw; and (e) the lock plate is movable from
a first position at which the lock nut rotates with the hollow
screw to a second position at which the lock nut cannot rotate, the
showerhead tilt adjustment mechanism providing coarse adjustment
when the lock plate is in the first position and fine adjustment
when the lock plate is in the second position. In making a coarse
adjustment, the lock plate of one of the showerhead tilt adjustment
mechanisms can be placed in the first position and the hollow screw
can be rotated to a first radial position. In making a fine
adjustment, the lock plate can be moved to the second position and
the hollow screw can be rotated to a second radial position at
which the IPD is reduced. The upper socket of the hollow screw can
include a slot extending through a wall of the socket and the
method can further comprise placing an indicator cap having an
upper alignment mark onto the hollow screw such that a projection
on the indicator cap fits within the slot, recording a
pre-adjustment angle of alignment mark, removing the indicator cap
and making the IPD adjustment, placing the indicator cap on the
hollow screw and recording a post-adjustment angle of the alignment
mark. By using first and second threaded sections having the same
orientation, each of the showerhead tilt adjustment mechanisms can
provide a coarse gap adjustment of about 0.02 to about 0.04 inch
per full rotation of the hollow screw when the lock plate is in the
first position and a fine gap adjustment of about 0.002 to about
0.004 inch per full rotation of the hollow screw when the lock
plate is in the second position.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0006] FIG. 1 illustrates a schematic diagram showing an overview
of a chemical deposition apparatus in accordance with embodiments
disclosed herein.
[0007] FIG. 2 illustrates a block diagram depicting various
apparatus components arranged for implementing embodiments
disclosed herein wherein plasma can be utilized to enhance
deposition and/or surface reactions between reacting species during
the generation of thin films.
[0008] FIG. 3A illustrates a cross-section and FIG. 3B illustrates
a top view of a showerhead module arranged in accordance with
embodiments disclosed herein.
[0009] FIGS. 4A-D illustrate gap tuning arrangements wherein FIGS.
4A-B show how coarse tuning is carried out with the lock plate not
engaged with a lock nut and FIGS. 4C-D show how fine tuning is
carried out with the lock plate engaged with the lock nut in
accordance with embodiments disclosed herein.
[0010] FIG. 5 illustrates how an indicator cap fits on the hollow
adjustment screw in accordance with an embodiment disclosed
herein.
[0011] FIG. 6 illustrates an indicator cap which mounts on a hollow
adjustment screw for indicating an angle of rotation after a gap
adjustment.
DETAILED DESCRIPTION
[0012] In the following detailed description, numerous specific
embodiments are set forth in order to provide a thorough
understanding of the apparatus and methods disclosed herein.
However, as will be apparent to those skilled in the art, the
present embodiments may be practiced without these specific details
or by using alternate elements or processes. In other instances,
well-known processes, procedures, and/or components have not been
described in detail so as not to unnecessarily obscure aspects of
embodiments disclosed herein. As used herein in connection with
numerical values the term "about" refers to .+-.10%.
[0013] As indicated, present embodiments provide semiconductor
substrate processing apparatuses such as deposition apparatuses (or
in an alternate embodiment an etching apparatus) and associated
methods for conducting a chemical vapor deposition such as a plasma
enhanced chemical vapor deposition. The apparatus and methods are
particularly applicable for use in conjunction with semiconductor
fabrication based dielectric deposition processes or metal
deposition processes which require separation of self-limiting
deposition steps in a multi-step deposition process (e.g., atomic
layer deposition (ALD), plasma enhanced atomic layer deposition
(PEALD), plasma enhanced chemical vapor deposition (PECVD), pulsed
deposition layer (PDL), molecular layer deposition (MLD), or plasma
enhanced pulsed deposition layer (PEPDL) processing), however they
are not so limited. Exemplary embodiments of methods of processing
a semiconductor substrate can be found in commonly-assigned U.S.
Published Patent Application Nos. 2013/0230987, 2013/0005140,
2013/0319329, and U.S. Pat. Nos. 8,580,697, 8,431,033, and
8,557,712, which are hereby incorporated by reference in their
entirety.
[0014] The aforementioned processes can suffer from some drawbacks
associated with non-uniform process gas delivery to an upper
surface of a wafer or semiconductor substrate receiving deposited
films from process gas such as a process gas precursor or reactant.
For example, a non-uniform precursor distribution on the upper
surface of the semiconductor substrate can form if a lower surface
of a showerhead module which delivers process gas to the
semiconductor substrate is not parallel to an upper surface of a
substrate pedestal module which supports the semiconductor
substrate. Several properties of film on wafer are impacted by the
gap/leveling between showerhead and pedestal, i.e. IPD, NU %,
Stress, etc. The sensitivity between these properties and the
gap/leveling are different for different process. And sometimes,
the normal resolution is not workable. To address this problem, an
improved leveling process is described herein wherein extra fine
resolution of a gap adjustment can be provided in a film deposition
apparatus.
[0015] There are generally two main types of CVD showerhead
modules: the chandelier type and the flush mount type. The
chandelier showerhead modules have a stem attached to a top plate
of the reaction chamber on one end and a faceplate on the other
end, resembling a chandelier. A part of the stem may protrude above
the top plate to enable connection of gas lines and connection to a
radio frequency ("RF") power circuit. Flush mount showerhead
modules are integrated into the top of a chamber and do not have a
stem. Although the examples shown herein are of a chandelier type
showerhead, the showerhead module is not limited to that type of
showerhead.
[0016] Showerhead module leveling (planarization) is typically
performed after a wet clean procedure that involves cooling and
venting a reaction chamber (chemical isolation chamber) of the
apparatus one or multiple times. The cooling and venting may be
required to access the interior of the chamber to adjust the
spacing between the showerhead and the substrate pedestal module as
well as the planarization of a lower surface of the showerhead with
respect to an upper surface of the pedestal module. A conventional
technique involves placing metallic foil balls in the chamber to
measure the gap between the showerhead module and the substrate
pedestal module and then adjusting a number of standoffs, usually
three or more, between a backing plate of the showerhead module and
the top plate of the reaction chamber based on the measurements.
The standoffs can only be adjusted by opening the top plate after
venting and cooling the chamber. Multiple measuring and adjusting
cycles may be performed before the showerhead module is considered
level. Because the showerhead cannot be leveled through external
manipulation, the process can be very time-consuming, up to about
20 hours.
[0017] In an embodiment, a gap adjustment is performed with screws
having differential threads. In this application, a screw and two
nuts are used. The screw has two threads with a different but close
pitch. Each nut has one pitch that matches the screw. With two
pairs of threads, the final pitch is the difference/sum of the two
pitches of the two pairs of threads. When the two threads are in
the same orientation, they can provide fine resolution. On the
other hand, when the two threads are in opposite orientation, they
can provide extra course resolution. By fixing both nuts, abnormal
resolution can be obtained, and by fixing only one nut and leaving
the other one free to rotate, normal resolution is available. Thus,
using the differential threads, the showerhead to wafer/pedestal
gap and other gaps can be adjusted with much finer/coarser
resolution compared with the normal gap tuning method. And with
this method, the gap can also be adjusted with the normal
resolution. In this way, the gap can be tuned more precisely or
faster. Thus, the showerhead to wafer/pedestal gap can be tuned
more precisely, which has a large impact on IPD/NU %/etc. of film
on wafers.
[0018] In accordance with an embodiment, differential threads are
used to adjust the showerhead to wafer/pedestal gap. In this way,
extra fine/coarse resolution can be provided. In the showerhead
module, an extra nut can be added without changing the mounting
plate and thereby provide a more retrofitable/cost saving tilt
adjustment arrangement. As an example, when the two threads on the
screw are in the same orientation, extra fine resolution is
available, and when they are in the opposite orientations, extra
coarse resolution is available. In another arrangement, final
resolution can be modified by changing the resolution of the two
threads. Due to space constraints in working on the tool, a tiny
wrench can be used to handle the extra nut and thus avoid the need
for a specially designed wrench/tool. The tiny wrench can be fixed
with an available screw in the existing assembly and avoid the need
to manually handle the wrench during tuning. If desired, the wrench
can be movable (wrench lock the extra nut or free the extra nut),
so the tuning can be changed between abnormal resolution and normal
resolution. As a visual aid during tilt adjustment, a mark on the
wrench can be used to indicate of its position, i.e., locking or
free position. Also, a cap with compass mark can be used to mate
with the screw head in a single orientation. This cap is removable
and before and after each tuning, a mark can be made on the cap
relative to a certain orientation. Then, the angle between the two
marks before and after the tuning can be measured to determine a
turned angle. In this way, no auto gapping system ("AGS") wafer
measurement is required for this application which can save a great
amount of time. A discussion of AGS wafer measurements can be found
in commonly-assigned U.S. Published Patent Application No.
2015/0225854, the disclosure of which is hereby incorporated by
reference.
[0019] Disclosed herein is a showerhead module coupled to a
showerhead tilt adjustment mechanism, which is designed to be
leveled from outside of the reaction chamber, between process steps
on the same wafer. In processes where two or more different film
materials are deposited sequentially, dynamically adjusting
showerhead tilt corrects for azimuthal variation without breaking
vacuum. The showerhead tilt adjustment mechanism includes the
differential screw tuning arrangement described above.
[0020] also described herein is a method of controlling in-plane
distortion (IPD) due to showerhead tilt in a semiconductor
substrate processing apparatus. The method includes measuring IPD
changes across a wafer processed in a processing chamber of the
semiconductor substrate processing apparatus and adjusting tilt of
a showerhead of the semiconductor substrate processing apparatus
using three showerhead tilt adjustment mechanisms having the
differential screw tuning arrangement described above which provide
coarse and fine IPD adjustments.
[0021] FIG. 1 is a schematic diagram showing an overview of a
semiconductor substrate processing apparatus 201 for chemical vapor
deposition in accordance with embodiments disclosed herein. A
semiconductor substrate 13 such as a wafer sits on top of a movable
pedestal module 223 that can be raised or lowered relative to a
showerhead module 211, which may also be moved vertically. Reactant
material gases are introduced into a processing zone 318 of the
chamber via gas line 203 wherein the process gas flow is controlled
by a mass flow controller 229. Note that the apparatus may be
modified to have one or more gas lines, depending on the number of
reactant gases used. The chamber is evacuated through vacuum lines
235 that are connected to a vacuum source 209. The vacuum source
may be a vacuum pump.
[0022] Embodiments disclosed herein can be implemented in a plasma
enhanced chemical deposition apparatus (i.e. plasma-enhanced
chemical vapor deposition (PECVD) apparatus, plasma-enhanced atomic
layer deposition (PEALD) apparatus, or plasma-enhanced pulsed
deposition layer (PEPDL) apparatus). FIG. 2 provides a simple block
diagram depicting various apparatus components arranged for
implementing embodiments disclosed herein wherein plasma is
utilized to enhance deposition. As shown, a processing zone 318
serves to contain the plasma generated by a capacitively coupled
plasma system including a showerhead module 211 working in
conjunction with a substrate pedestal module 223, wherein the
substrate pedestal module 223 is heated. RF source(s), such as at
least one high-frequency (HF) RF generator 204, connected to a
matching network 206, and an optional low-frequency (LF) RF
generator 202 are connected to the showerhead module 211. In an
alternative embodiment, the HF generator 204 can be connected to
the substrate pedestal module 223. The power and frequency supplied
by matching network 206 is sufficient to generate a plasma from the
process gas/vapor. In an embodiment both the HF generator and the
LF generator are used, and in an alternate embodiment, just the HF
generator is used. In a typical process, the HF generator is
operated at frequencies of about 2-100 MHz; in a preferred
embodiment at 13.56 MHz or 27 MHz. The LF generator is operated at
about 50 kHz to 2 MHz; in a preferred embodiment at about 350 to
600 kHz. The process parameters may be scaled based on the chamber
volume, substrate size, and other factors. Similarly, the flow
rates of process gas may depend on the free volume of the vacuum
chamber (reaction chamber) or processing zone.
[0023] Within the chamber, the substrate pedestal module 223
supports a substrate 13 on which materials such as thin films may
be deposited. The substrate pedestal module 223 can include a fork
or lift pins to hold and transfer the substrate during and between
the deposition and/or plasma treatment reactions. In an embodiment,
the substrate 13 may be configured to rest on a surface of the
substrate pedestal module 223, however in alternate embodiments the
substrate pedestal module 223 may include an electrostatic chuck, a
mechanical chuck, or a vacuum chuck for holding the substrate 13 on
the surface of the substrate pedestal module 223. The substrate
pedestal module 223 can be coupled with a heater block 220 for
heating substrate 13 to a desired temperature. Substrate 13 is
maintained at a temperature of about 25.degree. C. to 500.degree.
C. or greater depending on the material to be deposited.
[0024] In certain embodiments, a system controller 228 is employed
to control process conditions during deposition, post deposition
treatments, and/or other process operations. The controller 228
will typically include one or more memory devices and one or more
processors. The processor may include a CPU or computer, analog
and/or digital input/output connections, stepper motor controller
boards, etc.
[0025] In certain embodiments, the controller 228 controls all of
the activities of the apparatus. The system controller 228 executes
system control software including sets of instructions for
controlling the timing of the processing operations, frequency and
power of operations of the LF generator 202 and the HF generator
204, flow rates and temperatures of precursors and inert gases and
their relative mixing, temperature of the heater block 220 and
showerhead module 211, pressure of the chamber, tilt of the
showerhead, and other parameters of a particular process. Other
computer programs stored on memory devices associated with the
controller may be employed in some embodiments.
[0026] Typically there will be a user interface associated with
controller 228. The user interface may include a display screen,
graphical software displays of the apparatus and/or process
conditions, and user input devices such as pointing devices,
keyboards, touch screens, microphones, etc.
[0027] A non-transitory computer machine-readable medium can
comprise program instructions for control of the apparatus. The
computer program code for controlling the processing operations can
be written in any conventional computer readable programming
language: for example, assembly language, C, C++, Pascal, Fortran
or others. Compiled object code or script is executed by the
processor to perform the tasks identified in the program.
[0028] The controller parameters relate to process conditions such
as, for example, timing of the processing steps, flow rates and
temperatures of precursors and inert gases, temperature of the
wafer, pressure of the chamber, tilt of the showerhead, and other
parameters of a particular process. These parameters are provided
to the user in the form of a recipe, and may be entered utilizing
the user interface.
[0029] Signals for monitoring the process may be provided by analog
and/or digital input connections of the system controller. The
signals for controlling the process are output on the analog and
digital output connections of the apparatus.
[0030] The system software may be designed or configured in many
different ways. For example, various chamber component subroutines
or control objects may be written to control operation of the
chamber components necessary to carry out deposition processes.
Examples of programs or sections of programs for this purpose
include substrate timing of the processing steps code, flow rates
and temperatures of precursors and inert gases code, and a code for
pressure of the chamber.
[0031] The showerhead module 211 is preferably temperature
controlled and the pedestal is preferably RF powered. An exemplary
embodiment of a temperature controlled RF powered showerhead module
can be found in commonly-assigned U.S. Published Patent Application
No. 2013/0316094 which is hereby incorporated by reference in its
entirety.
[0032] According to embodiments disclosed herein, the showerhead
module preferably includes a showerhead tilt adjustment mechanism
for manually adjusting tilt, angle, gap and planarization of the
showerhead module. As illustrated in FIGS. 3A and 3B, a showerhead
module 211 preferably includes a stem 305, a base 315 which
includes a backing plate 317 and a faceplate 316 as well as the
showerhead tilt adjustment mechanism 400 for adjusting the
planarization of the showerhead module 211. The planarization of
the showerhead module 211 can also be coarsely adjusted by
tightening or loosening three adjustment screws 405 located
120.degree. apart. Adjustment screws 405 comprise a coarse thread
and a fine thread that can be used to manually adjust the
showerhead module 211 in tilt and in axial position. The adjustment
screws 405 mate with lock nuts and threaded bores in a leveling
plate as explained in more detail below.
[0033] In one embodiment, planarization of the faceplate 316 of the
showerhead module 211 can be adjusted using three tilt adjustment
mechanisms as part of a showerhead adjustment mechanism to manually
provide three degrees of freedom: an axial translation and two
directions of tilt. With reference to FIGS. 3A and 3B, the
showerhead module 211 is supported by a bellows assembly 500 which
includes a collar 502, bellows 504 and leveling plate 506. A
cooling plate 508 can be attached to the leveling plate 506.
[0034] As illustrated in FIG. 3A, the showerhead module 211 is
preferably supported in a top plate 330 of the chemical isolation
chamber (i.e. reaction chamber). The top plate 330 preferably
supports the collar 502 in a stepped bore. A horizontal upper
surface of the top plate 330 preferably has openings, such as
threaded openings, wherein corresponding openings, for receiving
fasteners 512, in the collar 502 include at least three fasteners
512 which attach the collar 502 to the top plate 330. The collar
502 supports the remainder of showerhead tilt adjustment mechanism
400 in the top plate 330. The showerhead tilt adjustment mechanism
400 is electrically grounded by the top plate 330.
[0035] An O-ring 514 forms an airtight seal (i.e. a hermetic seal)
between the leveling plate 506 and the cooling plate 508 supported
above the collar 502 by three adjustment screws 405 wherein the
three adjustment screws 405 are also operable to coarsely adjust
the planarization of the cooling plate 508 with respect to the
collar 502. As explained in more detail below, an upper end of each
adjustment screw 405 is threaded into a threaded bore of the
leveling plate 506 and a lower end of each respective adjustment
screw 405 is threaded into a lock nut 516 which is free to rotate
with the adjustment screw 405 when not engaged with lock plate 518
or the lock nut 516 can be locked by engagement with the lock plate
518 so as not to rotate when the adjustment screw 405 is rotated.
The showerhead stem 305 extends through a central opening in the
collar 502, the bellows 504, and the leveling plate 506 and an
upper end of the stem 305 is attached to the leveling plate 506 so
that the faceplate 316 can be tilted to a desired angle by rotation
of the adjustment screws 405.
[0036] The bellows 504 preferably forms an airtight expandable and
flexible vacuum seal between the collar 502 and the leveling plate
506 wherein the stem 305 extends through the airtight expandable
vacuum seal such that the planarization of the showerhead module
211 can be adjusted without breaking the airtight expandable vacuum
seal. The bellows 504 is preferably welded at an upper end to the
leveling plate 506 and at a lower end to the collar 502.
[0037] The showerhead tilt adjustment mechanism 400 may be attached
to the top plate 330 of a chemical isolation chamber via three or
more fasteners 512. The showerhead tilt adjustment mechanism
preferably includes three differential screw assemblies wherein
each differential screw assembly provides one degree of motion.
Three differential screw assemblies would give three degrees of
motion: two tilts and axial position.
[0038] FIGS. 4A-4D show further details of the showerhead tilt
adjustment mechanism and how the showerhead tilt mechanism can
provide coarse and fine gap adjustments. The adjustment screw 405
includes a first externally threaded section 405a engaged with an
internally threaded section 506a in an upwardly extending tubular
projection 506b on the leveling plate 506 and a second externally
threaded section 405b engaged with internal threads of the lock
screw 516. The first threaded section 405a and the second threaded
section 405b preferably have different thread pitches oriented in
the same direction. The upper end of the adjustment screw 405
includes a socket 405c which can engage a tool such as a hexagonal
screw driver (not shown) and a slot 405d in an upper portion of the
socket 405c is adapted to receive a projection of an indicator cap.
A fastener 520 such as a bolt is located inside the adjustment
screw 405 with a lower end 520a threaded into a threaded hole in
the collar 502 and an enlarged head 520b at the upper end received
inside the socket 405c. the head 520b fills a lower portion of the
socket 405c so that a tool such as a hexagonal screw driver can
engage the remainder of the socket 405c to rotate the adjustment
screw 405 during a gap/tilt adjustment.
[0039] The lock plate 518 includes a handle 518a at one end, a wide
slot 518b at the opposite end, and a narrow slot 518c extending
from the wide slot 518b. The shaft of fastener 512 extends through
the narrow slot 518c and allows the lock plate 518 to slide
radially inwardly to engage the lock nut 516. As shown in FIGS.
4A-4B, when the lock plate 518 is not engaged with the lock nut
516, the lock nut 516 rotates with the adjustment screw 405 to
provide a coarse gap adjustment. As shown in FIGS. 4C-4D, when the
lock plate 518 is engaged with the lock nut 516, the lock nut 516
is prevented from rotating with the adjustment screw 405 to provide
a fine gap adjustment. The lock plate 518 includes a reference mark
518d which provides a visual indication of when the lock plate 518
is not engaged with the lock nut 516 (reference mark 518d is
outside the outer periphery of leveling plate 506 as shown in FIGS.
4A-4B) and when the lock plate 518 is engaged with the lock nut 516
(reference mark 518d is inside the outer periphery of the leveling
plate 506 as shown in FIGS. 4C-4D).
[0040] FIG. 5 shows details of an indicator cap 522 fitted in the
socket 405c of the adjustment screw 405. The indicator cap 522
includes a projection 522a which fits in the slot 405d of the
adjustment screw 405. In making a gap/tilt adjustment, the
indicator cap 522 can be placed on the adjustment screw 405 and its
angular position can be recorded. Then, the indicator cap is
removed and a gap/tilt adjustment is performed by rotating the
adjustment screw 405 with the lock nut 516 not engaged with the
lock plate 518 or with the lock nut 516 engaged with the lock plate
518. When the gap/tilt adjustment is completed, the indicator cap
is placed on the adjustment screw 405 and its angular position is
recorded.
[0041] As shown in FIG. 6, the indicator cap can include a pointer
522b extending upwardly from a circular dial 522c having indicator
circumferentially spaced marks 522d which provide a visual
indication of the angular position of the pointer before and after
a gap/tilt adjustment.
[0042] The adjustment screw 405 may also be used for coarse and
fine adjustment of the showerhead module 211 position. Depending on
the choice of thread pitches, coarse adjustments in the range of
about 0.02 to about 0.04 inch and fine adjustments in the range of
about 0.002 to 0.004 inch per full rotation of the adjustment screw
405 can be achieved. For example, the coarse adjustment can be
0.03125 inch per full rotation of the adjustment screw and the fine
adjustment can be 0.0035 inch per full rotation of the adjustment
screw.
[0043] While the semiconductor substrate processing apparatus
including the baffle arrangement has been described in detail with
reference to specific embodiments thereof, it will be apparent to
those skilled in the art that various changes and modifications can
be made, and equivalents employed, without departing from the scope
of the appended claims.
* * * * *