U.S. patent application number 12/965804 was filed with the patent office on 2011-06-16 for showerhead assembly for vacuum processing apparatus.
Invention is credited to Wendell Thomas BLONIGAN, Michael Allen Renta.
Application Number | 20110139372 12/965804 |
Document ID | / |
Family ID | 43502633 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110139372 |
Kind Code |
A1 |
BLONIGAN; Wendell Thomas ;
et al. |
June 16, 2011 |
SHOWERHEAD ASSEMBLY FOR VACUUM PROCESSING APPARATUS
Abstract
Vacuum processing chambers having provisions for thermal
expansion and contraction. Specific embodiments provide a plasma
processing chamber having a showerhead that enables thermal
expansion and contraction without imparting structural stress on
the chamber body and without breaking any vacuum seal.
Inventors: |
BLONIGAN; Wendell Thomas;
(Pleasanton, CA) ; Renta; Michael Allen;
(Campbell, CA) |
Family ID: |
43502633 |
Appl. No.: |
12/965804 |
Filed: |
December 10, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61285505 |
Dec 10, 2009 |
|
|
|
Current U.S.
Class: |
156/345.34 ;
118/715; 29/525.02 |
Current CPC
Class: |
H01J 37/32733 20130101;
H01L 21/67754 20130101; H01L 21/67745 20130101; H01L 21/67748
20130101; C23C 16/45565 20130101; Y10T 29/49948 20150115; G06T
7/0004 20130101; H01L 21/67739 20130101; H01L 21/67173
20130101 |
Class at
Publication: |
156/345.34 ;
118/715; 29/525.02 |
International
Class: |
C23F 1/08 20060101
C23F001/08; C23C 16/455 20060101 C23C016/455; B23P 11/00 20060101
B23P011/00 |
Claims
1. A vacuum processing chamber, comprising: a chamber body; a
showerhead assembly coupled to top portion of the chamber body and
comprising: a back plate rigidly attached to the chamber body; a
perforated showerhead plate; a plurality of fastening assemblies
slidingly securing the showerhead plate to the back plate such that
the showerhead plate may slide with respect to the back plate; and,
wherein gas seal is maintained between the showerhead plate and the
back plate.
2. The vacuum processing chamber of claim 1, wherein the perforated
showerhead plate comprises a plurality of oval holes at periphery
thereof, and wherein each one of the plurality of fastening
assemblies is inserted in a respective one of the plurality of oval
holes.
3. The vacuum processing chamber of claim 1, wherein the showerhead
assembly further comprises an o-ring provided between the
showerhead plate and the back plate.
4. The vacuum processing chamber of claim 1, wherein the showerhead
assembly further comprises a spacer provided between the showerhead
plate and the back plate to thereby maintaining a small gap between
the showerhead plate and the back plate.
5. The vacuum processing chamber of claim 1, wherein the showerhead
plate further comprises a circular hole and a bolt passing through
the circular hole and fixedly securing the showerhead plate to the
back plate.
6. The vacuum processing chamber of claim 2, wherein the each of
the plurality of oval holes is oriented such that its long axis
lies along a straight line extending radially from the center of
the showerhead plate and passing through that oval hole.
7. The vacuum processing chamber of claim 6, wherein each of the
fastening assembly comprises a key to enable only one orientation
when the fastening assembly is seated within its respective oval
hole.
8. The vacuum processing chamber of claim 1, wherein each of the
fastening assemblies comprises a ball bearing assembly and a bolt
passing through the ball bearing assembly.
9. The vacuum processing chamber of claim 8, wherein the ball
bearing assembly comprises: an insert having an oval hole therein;
a sliding plate having a plurality of non-circular holes therein; a
plurality of balls, each for a corresponding one of the
non-circular holes; a cover plate having a circular hole
therein.
10. The vacuum processing chamber of claim 9, wherein the insert
further comprises a key to orient the insert inside one of the oval
holes of the showerhead plate.
11. The vacuum processing chamber of claim 9, wherein at least one
of the insert, sliding plate, plurality of balls, and cover plate,
is made of ceramic.
12. The vacuum processing chamber of claim 8, further comprising a
covering plate for covering the fastening assembly.
13. The vacuum processing chamber of claim 1, wherein each of the
fastening assembly comprises: an insert having an oval hole therein
and a sliding surface; a cover plate having a mating surface facing
the sliding surface; and, a bolt passing through the insert and the
cover plate.
14. The vacuum processing chamber of claim 1, wherein each of the
fastening assembly further comprises a sliding plate inserted
between the insert and the cover plate.
15. The vacuum processing chamber of claim 1, wherein the sliding
plate comprises a Teflon plate.
16. A method for securing a showerhead assembly onto a vacuum
processing chamber, comprising: fixedly attaching a back plate to
the vacuum processing chamber; coupling a perforated showerhead
plate to the back plate by using a plurality of fastening
assemblies to slidingly attach the perforated showerhead plate to
the back plate; and, providing a gas seal between the perforated
showerhead plate and the back plate.
17. The method of claim 16, wherein slidingly attaching comprises
bolting the perforated showerhead plate to the back plate via a
ball bearing assembly.
18. The method of claim 17, further comprising inserting a spacer
between the perforated showerhead plate and the back plate.
19. The method of claim 17, further comprising orienting each of
the ball bearing assembly such that it is aligned with an imaginary
line extending radially from the center of the showerhead
plate.
20. The method of claim 16, further comprising fixedly affixing the
showerhead plate to the back plate at one point.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority
from U.S. Provisional Application Ser. No. 61/285,505, filed on
Dec. 10, 2009, the entire content of which is incorporated herein
by reference.
BACKGROUND
[0002] 1. Field
[0003] The invention concerns a vacuum processing apparatus, such
as plasma chambers used for etching or forming thin films on
substrates or other workpieces.
[0004] 2. Related Art
[0005] Manufacturing processes in the fields of semiconductor, flat
panel displays, solar panels, etc., involve processing in vacuum
chambers. For example, vacuum chambers are used for plasma-enhanced
chemical vapor deposition (PECVD), plasma etching and various other
processes for forming thin films on substrates (workpieces) and
etching structures on the substrates. In such chambers, various
gases are flowed into the chamber, either via injectors or via a
showerhead. For uniform plasma processing in large chambers, a
showerhead is preferable over injectors. The showerhead would
generally cover substantially the entire ceiling of the chamber, so
that even amount of gas is injected everywhere within the
chamber.
[0006] As gas is flowed into the chamber, plasma is ignited and
sustained using radio frequency or microwave energy. This heats up
the chamber. Also, for many processes active heaters are used to
heat the substrates, which further add to heating of the chamber.
Of course, when the processed substrates are removed from the
chamber and fresh ones are introduced into the chamber, the chamber
cools down until plasma is ignited again. These changes in
temperatures cause various parts of the chamber to expand and
contract. Parts made of different material would expand and
contract at different rates. Also, large parts in large chamber
would expand considerably. This is especially true for showerheads
of large processing chambers, such as those used for fabrication of
flat panel displays or solar cell.
SUMMARY
[0007] The following summary of the invention is included in order
to provide a basic understanding of some aspects and features of
the invention. This summary is not an extensive overview of the
invention and as such it is not intended to particularly identify
key or critical elements of the invention or to delineate the scope
of the invention. Its sole purpose is to present some concepts of
the invention in a simplified form as a prelude to the more
detailed description that is presented below.
[0008] Embodiments of the invention provide vacuum processing
chambers having provisions for thermal expansion and contraction.
Specific embodiments of the invention provide a plasma processing
chamber having a showerhead that enables thermal expansion and
contraction without imparting structural stress on the chamber body
and without breaking any gas seal.
[0009] According to an embodiment of the invention, a plasma
chamber is provided wherein the showerhead assembly anchors the
showerhead at one point, while allowing sliding of the shower at
other points in order to allow for thermal expansion and
contraction. According to another embodiment, no anchoring is
provided, and the showerhead may slide in all directions while
maintaining gas seal.
[0010] According to an embodiment of the invention, a vacuum
processing chamber is provided, comprising: a chamber body; a
showerhead assembly coupled to top portion of the chamber body and
comprising: a back plate rigidly attached to the chamber body; a
perforated showerhead plate having a plurality of oval holes; and,
a plurality of fastening assemblies that slidingly attach the
showerhead plate to the back plate to thereby allow sliding of the
showerhead plate relative to the back plate while gas seal is
maintained between the showerhead plate and the back plate.
According to one embodiment, at least one bolt rigidly attaches the
showerhead plate to the back plate.
[0011] According to an embodiment of the invention, a method for
securing a showerhead assembly onto a vacuum processing chamber is
provided, comprising: fixedly attaching a back plate to the vacuum
processing chamber; coupling a perforated showerhead plate to the
back plate by using a plurality of fastening assemblies to
slidingly attach the perforated showerhead plate to the back plate;
and, providing a gas seal between the perforated showerhead plate
and the back plate. According to one embodiment, the method further
comprises fixedly attaching at least one location of the perforated
showerhead plate to the back plate.
[0012] Other aspects and features of the invention will become
apparent from the description of various embodiments described
herein, and which come within the scope and spirit of the invention
as claimed in the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
[0013] The accompanying drawings, which are incorporated in and
constitute a part of this specification, exemplify the embodiments
of the present invention and, together with the description, serve
to explain and illustrate principles of the invention. The drawings
are intended to illustrate major features of the exemplary
embodiments in a diagrammatic manner. The drawings are not intended
to depict every feature of actual embodiments nor relative
dimensions of the depicted elements, and are not drawn to
scale.
[0014] FIG. 1 is a schematic illustrating major elements of a
plasma processing chamber implementing an embodiment of the
invention.
[0015] FIG. 2 is a cross section illustrating one example of
anchoring one side of the showerhead, according to an embodiment of
the invention.
[0016] FIG. 3 is a cross section illustrating one example of
floating one side of the showerhead, according to an embodiment of
the invention.
[0017] FIG. 4 is an explosive view illustrating a floating
mechanism according to an embodiment of the invention.
[0018] FIG. 5 is an isometric view of the assembled floating
attachment.
[0019] FIG. 6 is a lower elevation of the cover plate 176, showing
its underside.
[0020] FIG. 7 illustrates a sliding fastening mechanism according
to another embodiment of the invention.
[0021] FIGS. 8A and 8B are bottom elevation view of the back plate
and the showerhead plate according to an embodiment of the
invention.
DETAILED DESCRIPTION
[0022] FIG. 1 is a schematic illustrating major elements of a
plasma processing chamber 100 implementing an embodiment of the
invention. The chamber 100 includes a chamber body 102, generally
made of metal, such as aluminum, stainless steel, etc. A pedestal
105 is provided for holding one or more substrates. The pedestal
105 may support a susceptor, a chuck, and/or a heater. The pedestal
may be attached to a lift mechanism 115, so that it is lowered to
the illustrated position for substrates loading via the valve 110,
and then lifted up for processing. At its top, the chamber has a
showerhead assembly that includes a showerhead plate 120 attached
to a back plate 125. The back plate 125 is secured hermetically to
the chamber body 102. Gas is supplied to the showerhead from source
130, via conduit 135. The showerhead plate 120 has many
perforations that allow the gas to disperse into the chamber.
[0023] FIG. 2 is a cross section illustrating one example of
anchoring one location of the showerhead plate 120 to the back
plate 125, according to an embodiment of the invention. According
to an embodiment of the invention, at least one point of the shower
plate 120 is anchored to the back plate 125, such that it is sealed
to the back plate 125 to avoid gas leaks, and such that it cannot
move relative to the back plate 125 at that point. This point may
be, for example, one of the corners or the center of the showerhead
plate. The illustration of FIG. 2 shows the example of anchoring at
one corner of the showerhead plate.
[0024] FIG. 3, on the other hand, shows example of the sliding
fastening assemblies used to slidingly attach the showerhead to the
backplate, according to an embodiment of the invention. That is, in
this embodiment, at least the diametrically opposing side of the
showerhead plate 120 is attached to the back plate 125 in a
floating manner, such that it is sealed to the back plate 125, but
can slide with respect to the back plate 125 at that location. In
this manner, expansion and contraction of the showerhead plate 120
is enabled, as it is free to slide with respect to the back plate
125, while still keeping the seal to it to avoid processing gas
escaping from between the showerhead plate and the back plate.
[0025] As shown in FIGS. 2 and 3, an o-ring 140 is provided between
the showerhead plate 120 and back plate 125, so as to provide gas
seal between the showerhead plate 120 and the back plate 125. A
Teflon block or spacer 145 is also provided between the showerhead
plate 120 and the back plate 125, such that it maintains a small
gap between the showerhead plate 120 and the back plate 125,
enabling sliding motion therebetween. In FIG. 2, the showerhead
plate 120 is securely bolted to the back plate 125 using bolt 150
and washer 155. A cover 160 is provided to cover the bolt 150.
[0026] FIG. 3 illustrate the sliding fastening assembly that is
used to attach the showerhead plate 120 to the back plate 125 in a
manner providing gas seal but allowing sliding of the showerhead
plate 120 for thermal expansion and contraction. While in FIG. 2 a
hole 152 having a diameter just sufficient to accommodate the bolt
150 is drilled in the showerhead plate, for the sliding fastening
assembly illustrated in FIG. 3 the hole 154 is of oval shape and
includes a step 156. An insert 170 is inserted into the hole 154,
such that it is seated against the step 156. The insert may be made
of ceramic or other material.
[0027] FIG. 4 is an exploded view of the sliding fastening
mechanism according to one embodiment of the invention. As shown in
FIG. 4, the insert 170 has a hole 172 that is of slightly larger
diameter than the diameter of the bolt 150 and is oval in shape.
Also, as shown in FIG. 4, the insert 170 includes a key 171, so
that it can be inserted into hole 154 in only one orientation, such
that the long axis of the oval hole 172 is in the direction of
expansion of the showerhead plate 120 at that location.
[0028] A sliding plate 173 is provided over the insert 170. The
sliding plate 173 has four oval holes 174, which are also oriented
in the direction of sliding. In each of the holes, a ball 175 is
inserted. Each ball 175 can ride freely inside its respective oval
hole 174. A cover plate 176 is provided over the assembly of the
sliding plate 173 and balls 175. It can be appreciated that the
insert 170, sliding plate 173, balls 175 and cover plate 176,
essentially form a "linear" ball bearing arrangement. Two optional
washers 177, 178 are provided over the cover plate 176, and a bolt
150 tightens the entire assembly onto the back plate 125. As can be
understood, under proper tightening of the bold 150, the showerhead
plate 120 can be sealed to the backplate 150, but also be able to
expand by sliding with respect to the backplate 125. When this
occurs, the assembly of showerhead plate 120 and insert 170 "ride"
on balls 175, since the hole 172 provided in the insert 170 is oval
in the direction of expansion motion. In this embodiment, all of
the parts, except for the bolt 150, are made of ceramic, but other
materials may be used for the various parts, such as aluminum,
anodized aluminum, Teflon, etc.
[0029] FIG. 5 illustrates the entire sliding fastening arrangement
with bolt 150 inserted thorough the washers 177/178, the cover
plate 176, the sliding plate 173, and the insert 170. This entire
assembly is inserted into the hole 154, shown in FIG. 3, and the
bolt is tightened so as to form a seal with o-ring 140, but allow
sliding of the showerhead plate 120, assisted by the Teflon
block.
[0030] FIG. 6 is a lower elevation of the cover plate 176, showing
its underside. As shown in FIG. 6, according to one embodiment,
four races are provided on the bottom face of the cover plate, such
that the balls 175 can freely roll in one linear direction dictated
by the race.
[0031] FIG. 7 illustrate a sliding fastening mechanism according to
another embodiment of the invention. The sliding fastening
mechanism according to this embodiment is similar to that shown in
FIGS. 3 and 4, except that balls 175 are eliminated and the sliding
is enables by simple friction. According to one embodiment, cover
176 "rides" on insert 170 and sliding there-between occurs at
interface 175'. According to another embodiment, the surfaces of
the cover 176 and insert 170 which form interface 175' are treated
to provide reduce friction and avoid or reduce particle generation
caused by the sliding. This can be done by, for example, by coating
the surfaces with, e.g., Teflon, anodization, etc. According to yet
another embodiment, a disk made of smooth material, such as Teflon,
is provided at the interface 175'.
[0032] According to another embodiment, the showerhead plate is not
fixedly attached to the back plate. Rather, a plurality of sliding
fastening assemblies are used to attach the showerhead plate to the
back plate, so that it is free to expand in all directions.
However, the plurality of sliding fastening assemblies are oriented
such that the center of the showerhead plate remains at the same
location regardless of expansion or contraction of the showerhead
plate. This is illustrated in FIGS. 8A and 8B.
[0033] FIGS. 8A and 8B are bottom elevation views of the back plate
125 (shown in broken line) and the showerhead plate 120 according
to an embodiment of the invention. The broken-line arrows
illustrate straight-line directions from the center of the
showerhead plate, extending radially and passing through the center
of each point where a fastening assembly is provided. As
illustrated, each of the oval holes 154 of the fastening assembly
is oriented such that its long axis lies along the straight line
extending radially from the center of the showerhead plate. As
explained above, each of the inserts 170 includes a key, such that
when it is inserted into a hole 154 it assumes an orientation so
that the long axis of its oval hole 172 is also oriented along the
straight line extending radially from the center of the showerhead
plate. In this manner, at each point where a fastening assembly is
provided, the showerhead can slide only along the direction of the
straight line extending radially from the center of the showerhead
plate and passes through that point. Consequently, it can be
understood that the showerhead can expand and contract in all
directions by sliding or riding on the fastening assemblies, but
because of the orientation of the fastening assemblies the center
of the showerhead remains at the same location regardless of the
expansion and contraction of the showerhead plate. That is, the
orientations of the fastening mechanisms prevent any rotation or
translation of the showerhead plate, other than radial expansion
and contraction.
[0034] FIG. 8A illustrate the showerhead plate in its expanded
position. As shown, the showerhead plate has expanded such that the
bolts 150 are on the inner-radial side of the oval holes 154.
Conversely, in FIG. 8B, illustrating the contracting position, the
bolts 150 are shown at the outer-radial side of the oval holes
154.
[0035] While the invention has been described with reference to
particular embodiments thereof, it is not limited to those
embodiments. Specifically, various variations and modifications may
be implemented by those of ordinary skill in the art without
departing from the invention's spirit and scope, as defined by the
appended claims. Additionally, all of the above-cited prior art
references are incorporated herein by reference.
* * * * *