U.S. patent application number 11/557037 was filed with the patent office on 2007-03-15 for apparatus and methods for preventing rotational slippage between a vertical shaft and a support structure for a semiconductor wafer holder.
This patent application is currently assigned to ASM AMERICA, INC. Invention is credited to Lewis C. Bernett, Michael W. Halpin, Loren R. Jacobs, Thomas M. Weeks, Eric R. Wood.
Application Number | 20070056150 11/557037 |
Document ID | / |
Family ID | 34808160 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070056150 |
Kind Code |
A1 |
Weeks; Thomas M. ; et
al. |
March 15, 2007 |
APPARATUS AND METHODS FOR PREVENTING ROTATIONAL SLIPPAGE BETWEEN A
VERTICAL SHAFT AND A SUPPORT STRUCTURE FOR A SEMICONDUCTOR WAFER
HOLDER
Abstract
A substrate support assembly positively secures a substrate
holder support to a rotation shaft with respect to rotationally
applied forces. A substrate holder support is configured to have an
opening in a socket into which, when aligned with an indentation in
the rotational shaft to form a passage, a retaining member is
removably inserted to engage both the socket opening and the shaft
indentation. Methods of rotating a substrate while minimizing
rotational slippage of the substrate holder support with respect to
the shaft are also provided.
Inventors: |
Weeks; Thomas M.; (Gilbert,
AZ) ; Bernett; Lewis C.; (Tempe, AZ) ; Jacobs;
Loren R.; (Chandler, AZ) ; Wood; Eric R.;
(Queen Creek, AZ) ; Halpin; Michael W.;
(Scottsdale, AZ) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
ASM AMERICA, INC
Phoenix
AZ
|
Family ID: |
34808160 |
Appl. No.: |
11/557037 |
Filed: |
November 6, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10769549 |
Jan 30, 2004 |
7169234 |
|
|
11557037 |
Nov 6, 2006 |
|
|
|
Current U.S.
Class: |
29/25.01 ;
118/730; 414/935 |
Current CPC
Class: |
H01L 21/68792 20130101;
C23C 16/4584 20130101; H01L 21/68728 20130101 |
Class at
Publication: |
029/025.01 ;
414/935; 118/730 |
International
Class: |
H01L 21/00 20060101
H01L021/00; C23C 16/00 20060101 C23C016/00 |
Claims
1. A support assembly for supporting a substrate holder during
semiconductor substrate processing, comprising: a substrate holder
support configured to support a semiconductor substrate holder, the
substrate holder support having a socket; and a rotational drive
having an end portion with one or more tapered surfaces, the end
portion and the one or more tapered surfaces adapted to be slidably
received within the socket of the substrate holder support, the end
portion and the socket being shaped to precisely fit together so as
to substantially prevent rotational slippage of the rotational
drive with respect to the socket, the rotational drive configured
to support and rotate the substrate holder support during rotation
of the rotational drive.
2. The support assembly of claim 1, further comprising a substrate
holder supported by the substrate holder support.
3. The support assembly of claim 1, wherein the substrate holder
support includes a plurality of support arms extending generally
radially outward and upward from the socket, the support arms
adapted to support a substrate holder.
4. The support assembly of claim 1, wherein the rotational drive
comprises a shaft portion having said one or more tapered
surfaces.
5. A support assembly for supporting a substrate holder during
semiconductor substrate processing, comprising: a substrate holding
structure configured to support a semiconductor substrate during
substrate processing; and a rotational linkage adapted to support
the substrate holding structure; wherein a shaped section of the
substrate holding structure is adapted to be coupled to a
correspondingly shaped section of the rotational linkage so as to
substantially prevent rotational slippage of the substrate holding
structure relative to the rotational linkage, the correspondingly
shaped section of the rotational linkage including one or more
tapered surfaces.
6. The support assembly of claim 5, wherein the substrate holding
structure comprises: a substrate holder adapted to support a
semiconductor substrate during substrate processing; and a
substrate holder support adapted to support the substrate holder
and to be supported by the rotational linkage.
7. The support assembly of claim 5, wherein the shaped section of
the substrate holding structure comprises a socket adapted to
slidably receive the correspondingly shaped section of the
rotational linkage.
8. The support assembly of claim 7, wherein the substrate holding
structure comprises: a substrate holder adapted to support a
substrate during substrate processing; and a substrate holder
support comprising said socket and a plurality of support arms
extending generally radially outward and upward from the socket,
the support arms adapted to support the substrate holder.
9. The support assembly of claim 5, wherein the rotational linkage
comprises a shaft portion having said one or more tapered
surfaces.
10. A method of processing a semiconductor substrate, comprising:
providing a rotational drive having an upwardly terminating end
portion having one or more tapered surfaces; providing a substrate
holder support having a socket adapted to slidably receive the end
portion and the one or more tapered surfaces of the rotational
drive, the end portion and the socket being shaped to precisely fit
together so as to substantially prevent rotational slippage of the
rotational drive with respect to the socket; aligning the socket
with the end portion of the rotational drive; lowering the socket
onto the end portion of the rotational drive so that the end
portion and the socket precisely fit together; supporting a
substrate holder on the substrate holder support; supporting a
semiconductor substrate on the substrate holder; and rotating the
rotational drive so as to rotate the substrate holder support, the
substrate holder, and the substrate.
11. The method of claim 10, wherein providing the substrate holder
support comprises providing a plurality of support arms extending
generally radially outward and upward from the socket, and wherein
supporting the substrate holder on the substrate holder support
comprises supporting the substrate holder on the support arms.
12. The method of claim 10, wherein providing the rotational drive
comprises providing a shaft portion having said one or more tapered
surfaces.
13. A method of processing a semiconductor substrate, comprising:
providing a rotational linkage; providing a substrate holding
structure adapted to support a semiconductor substrate during
substrate processing; engaging a shaped section of the substrate
holding structure with a correspondingly shaped section of the
rotational linkage so that the rotational linkage supports the
substrate holding structure and so that rotational slippage of the
substrate holding structure relative to the rotational linkage is
substantially prevented, the correspondingly shaped section of the
rotational linkage including one or more tapered surfaces;
supporting a semiconductor substrate on the substrate holding
structure; and rotating the rotational linkage so as to rotate the
substrate holding structure and the substrate.
14. The method of claim 13, wherein providing the substrate holding
structure comprises providing a substrate holder and a substrate
holder support, the substrate holder being adapted to support the
substrate during substrate processing, the substrate holder support
being adapted to support the substrate holder, the substrate holder
support including said shaped section engaged with said
correspondingly shaped section of the rotational linkage.
15. The method of claim 13, wherein engaging the shaped section of
the substrate holding structure with the correspondingly shaped
section of the rotational linkage comprises slidably inserting the
correspondingly shaped section of the rotational linkage into a
socket of the substrate holding structure.
16. The method of claim 15, wherein providing the substrate holding
structure comprises: providing a substrate holder adapted to
support the substrate during substrate processing; and supporting
the substrate holder on upper ends of a plurality of support arms
of a substrate holder support, the support arms extending generally
radially outward and upward from the socket.
17. The method of claim 13, wherein providing the rotational
linkage comprises providing a shaft portion having said one or more
tapered surfaces.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of and claims priority to
co-pending U.S. patent application Ser. No. 10/769,549, filed Jan.
30, 2004, the entire disclosure of which is incorporated by
reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention generally relates to the field of substrate
processing and, more particularly, to apparatuses and methods for
preventing relative rotation of a vertical support shaft and a
support structure for a wafer holder.
[0004] 2. Description of the Related Art
[0005] In the processing of substrates, such as semiconductor
wafers, a substrate or wafer holder is generally employed inside a
reaction chamber to both evenly support a wafer and to ensure even
heat distribution across the surface of the wafer. If the wafer
holder helps to attract radiant energy, it is called a susceptor.
The susceptor or wafer holder is supported by an underlying support
(e.g., a quartz "spider") having a socket which is configured to
mate with a portion of an elongated rotation shaft. In one common
configuration, the shaft is rotationally linked to a motor, which
effectuates the rotation of the support. In turn, the wafer holder
supported by the rotating wafer holder support is also rotated, as
is the wafer resting upon the wafer holder. During wafer processing
(e.g., chemical vapor deposition, physical vapor deposition,
etching, etc.) it is desirable for the wafer to be evenly rotated.
Even small deviations in the speed of rotation or "wobble" can
result in uneven processing of the wafer surface, which is
generally undesirable.
[0006] In the past, wafer holders have been designed for 200 mm
wafers. Currently, larger, heavier wafer holders configured to
accommodate 300 mm wafers are used more frequently due to their
higher semiconductor device yield (e.g., microchip) made possible
by the larger surface area of 300 mm wafers.
SUMMARY OF THE INVENTION
[0007] Although rotational slippage between the wafer holder
support (also referred to herein as a spider) and rotation shaft is
a problem that has been known to occasionally occur on 200 mm
systems, the rotational inertia of the 300 mm susceptor is 6.1
times greater than that of the 200 mm systems. Therefore, the
probability of the spider slipping with respect to the rotation
shaft is much greater. Slippage between a spider socket and the
rotation shaft causes polishing of the precisely machined mating
surfaces of the shaft and the socket interior, thereby deforming
the mating surfaces so that the shaft and the spider socket no
longer precisely fit together. This polishing of the machined
surfaces of the shaft and socket interior can lead to further
slippage of the surfaces with respect to one another. In addition,
this polishing can also introduce wafer holder wobble. Rotational
slippage of the spider socket with respect to the shaft can also
generate particulate contamination by depositing dust around the
tubulation on the bottom of the reaction chamber.
[0008] The present invention addresses the aforementioned problems,
among others, by providing apparatuses and methods of rotationally
locking the wafer holder support (or "spider") to the shaft.
Advantageously, implementation of a wafer holder support
rotationally locked to the shaft aids in the prevention of
undesirable rotational slippage, thereby ensuring appropriate
substrate or wafer orientation. In addition, preferred embodiments
of the present invention can be freely lifted in a vertical
direction, even when the wafer holder support is rotationally
locked to the shaft. Preferred embodiment also decrease wafer
holder support wobble, thereby helping to ensure uniform
deposition. Preferred embodiments also reduce the likelihood of
undesirable generation of particulate contaminants generated by
friction between shifting components. Preferred embodiments allow
for easy assembly and disassembly of the provided parts, in
addition to maintaining the productive life of individual
parts.
[0009] In accordance with one aspect of the present invention, a
support assembly for supporting a substrate holder during substrate
processing is provided. The assembly includes a substrate holder
support which prevents rotational slippage of the substrate holder
support relative to a rotational drive.
[0010] In a preferred embodiment, a retaining member is inserted
into an opening in the substrate holder support socket so that the
retaining member contacts an indentation or contact surface of the
rotational drive or shaft when the shaft is inserted in the
substrate holder support socket and rotational slippage of the
substrate holder support relative to the shaft is thereby
prevented. In one preferred embodiment, the retaining member is a
L-shaped member, while in another preferred embodiment the
retaining member is a flexible member which is U-shaped when
engaged with the opening in the substrate holder support socket. In
yet other preferred embodiments, the retaining member is a comer
shaped retaining member, while in another preferred embodiment the
retaining member is a key which is configured to straddle an arm of
the substrate holder support while being inserted in the opening in
the substrate holder socket.
[0011] In accordance with another aspect of the present invention,
a substrate processing system is provided. The system includes a
support member having a receptor and a plurality of arms extending
generally radially outward from the receptor. The arms support an
underside of a holder and the receptor has a hole in a sidewall of
the receptor. The system also includes a locking key and a
rotational linkage. The rotational linkage has an end portion
configured to be received within the receptor such that the
rotational linkage is at least partially rotatable with respect to
the receptor about a longitudinal axis of the rotational linkage.
The end portion of the rotational linkage also has at least one
retaining surface. The at least one retaining surface and the hole
are configured so that when the rotational linkage is rotated to a
locking position, the at least one retaining surface and the hole
together form a passage sized and configured to receive the locking
key. The locking key thereby prevents the support member from
rotating independently of the rotational linkage.
[0012] In accordance with another aspect of the present invention,
a method of assembling a rotating susceptor assembly for a
semiconductor processing system is provided. A substrate holding
structure is coupled to a rotational linkage so as to prevent
rotational slippage of the susceptor holding structure relative to
the rotational linkage during rotation of the substrate holding
structure.
[0013] In accordance with another aspect of the present invention,
a method of rotating a substrate is provided. A susceptor assembly
is rotated by coupling a substrate holding assembly to a rotational
linkage so as to prevent rotational slippage of the susceptor
holder support relative to the a rotational source when the
substrate holding assembly is rotated. In a preferred embodiment,
the substrate holding assembly is placed on the rotational linkage
and rotated until the assembly drops into an engaged position.
[0014] In another preferred embodiment, the substrate holder
support includes a rotational drive interface. A rotational drive
and the rotational drive interface are shaped to precisely fit
together to prevent rotational slippage of the substrate holder
support relative to the rotational drive.
[0015] In another preferred embodiment, a substrate rotating system
is provided. The system includes a shaped rotational shaft and a
susceptor support correspondingly shaped to be joined with the
rotational shaft so as to prevent rotational slippage between the
shaft and the susceptor support.
[0016] For purposes of summarizing the invention and the advantages
achieved over the prior art, certain objects and advantages of the
invention have been described herein above. Of course, it is to be
understood that not necessarily all such objects or advantages may
be achieved in accordance with any particular embodiment of the
invention. Thus, for example, those skilled in the art will
recognize that the invention may be embodied or carried out in a
manner that achieves or optimizes one advantage or group of
advantages as taught herein without necessarily achieving other
objects or advantages as may be taught or suggested herein.
[0017] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments of
the present invention will become readily apparent to those skilled
in the art from the following detailed description of the preferred
embodiments having reference to the attached figures, the invention
not being limited to any particular preferred embodiment(s)
disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1A is a bottom cross-sectional view of a prior art
support assembly, comprising a shaft, substrate holder support and
substrate holder, taken along line 1A-1A of FIG. 1B;
[0019] FIG. 1B is a side cross-sectional view of the prior art
support assembly shown in FIG. 1A, taken along line 1B-1B of FIG.
1A;
[0020] FIG. 2A is a schematic side view of a support assembly
according to one embodiment of the invention, employing an
elbow-shaped retaining member, a shaft having an indentation for
receiving the retaining member, and a securing member for securing
the retaining member in place;
[0021] FIG. 2B is a schematic top view of the support assembly
shown in FIG. 2A;
[0022] FIG. 2C is a magnified view of the retaining member employed
in the support assembly of FIGS. 2A and 2B;
[0023] FIG. 2D is a side cross-sectional view of the support
assembly of FIGS. 2A and 2B, taken along line 2D-2D of FIG. 2B,
selected to show more clearly the position and orientation of the
retaining member with respect to the shaft indentation;
[0024] FIG. 3A is a magnified perspective view of an elongated
support shaft in accordance with one embodiment of the present
invention, the shaft having a tapered end portion and a single
indentation therein;
[0025] FIG. 3B is a top view of the shaft of FIG. 3A;
[0026] FIG. 3C is a top view of another embodiment of an elongated
support shaft of the present invention, having a tapered tip and
multiple shaft indentations;
[0027] FIG. 4A is a schematic top perspective view of a support
assembly according to another embodiment of the present invention,
employing a flexible retaining member;
[0028] FIG. 4B is a top cross-section of the support assembly shown
in Figure 4A;
[0029] FIG. 4C is a magnified view of an alternate embodiment of
the flexible retaining member shown in FIGS. 4A and 4B, shown in a
flexed position;
[0030] FIG. 4D is a magnified view of the spring-type retaining
member of FIG. 4C in a relaxed position;
[0031] FIG. 5A is a bottom perspective view of a portion of a
support assembly according to another embodiment of the invention,
employing a retaining member having ears for securing it into a
comer defined by two of the spider arms, the elongated shaft not
being shown in order to more clearly illustrate the position of the
retaining member when locked in place;
[0032] FIG. 5B is a side perspective view of the support assembly
of FIG. 5A with the elongated shaft inserted into the spider
socket;
[0033] FIG. 5C is a top view of the retaining member shown in FIGS.
5A and 5B;
[0034] FIG. 5D is a side view of one of the locking pins of the
support assembly of FIGS. 5A and 5B;
[0035] FIG. 6A is a top view of a support assembly in accordance
with yet another alternate embodiment of the present invention,
having a spider arm slot that accepts a retaining member having two
prongs configured to straddle a wall portion defined by the
slot;
[0036] FIG. 6B is a side cross-section of the support assembly of
FIG. 6A taken along line 6B-6B.
[0037] FIG. 6C shows the support assembly of FIG. 6B with the
retaining member engaged within the spider arm slot;
[0038] FIG. 6D is a horizontal cross-sectional view taken along
line 6D-6D of FIG. 6C;
[0039] FIG. 7 is a top cross-sectional view of an alternate
embodiment employing a shaped socket in conjunction with a
correspondingly shaped shaft;
[0040] FIG. 8 is a flow chart illustrating a method of assembling a
rotating susceptor assembly, in accordance with a preferred
embodiment of the present invention; and
[0041] FIG. 9 is a flow chart illustrating a method of rotating a
substrate holder support, in accordance with another preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] FIGS. 1A and 1B are schematic depictions of a support
assembly 6 of the prior art. A substrate (or wafer) holder support,
or spider 10, is shown in a reaction chamber 11. The spider 10 has
a plurality of support arms 12 extending radially outward and
upward from a central socket 14 to support the underside of a
substrate holder 16, such as a susceptor. The substrate holder 16
rests upon the support arms 12 and is configured to hold a
substrate or wafer 18. Underneath the spider 10, an elongated shaft
20 is mated with the spider socket 14, providing a coupling that
allows the spider 10 to be rotated when the elongated shaft 20 is
rotated by a motor 22. As explained above in the Background
section, this coupling does not satisfactorily prevent relative
rotation between the shaft 20 and the socket 14, particularly when
the mass of the system has increased by movement from 200 mm wafers
to 300 mm wafers. Also, as the mating surfaces rub against one
another and deform, wobbling of the substrate holder support is
introduced, which adversely affects wafer processing.
[0043] FIGS. 2A-2D show a support assembly 8 according to one
embodiment of the present invention. The assembly 8 includes an
elbow-shaped retaining member 22 or locking key having an engaging
portion 24 and a securing portion 32. The engaging portion 24 is
configured to be inserted into an opening 26 in a side wall 28 of
the socket 14 when both the socket opening 26 and an indentation 30
in the shaft 20 are aligned to provide a preferably continuous
passage for the retaining member 22. The retaining member 22
preferably substantially fills the opening 26. Preferably, the
indentation 30 is a flattened, planar portion on an otherwise
curved surface on the shaft 20 (see FIGS. 3A-3C). When so inserted,
the retaining member 22 is in an engaged position. The opening 26
may extend partially through one of the support arms 12 of the
spider 10, as shown. When in an engaged position, the engaging
portion 24 of the retaining member 22 preferably protrudes from the
socket side wall 28 on the opposite side of the support arm 12 from
which the retaining member 22 was inserted. The inserted retaining
member 22 serves to secure the spider 10 (and therefore the wafer
holder 16 (FIG. 1A) supported by the spider 10) to the elongated
shaft 20 inserted therein by engaging both the socket opening 26
and the indentation 30 (FIG. 3) in the elongated shaft 20.
Engagement of both the socket opening 26 and the shaft indentation
30 by the retaining member 22 preferably prevents the shaft 20 from
rotating with respect to the spider socket 14, i.e. rotational
slippage.
[0044] Preferably, embodiments of the present invention employ
locking features configured to prevent rotational slippage when a
retaining member 22 is in an engaged position, without preventing
the spider 10 from being lifted vertically in order to remove the
spider 10 from the shaft 20 or rotational drive or rotational
linkage. In other words, the retaining member (e.g., locking key)
locks the support member to the rotational drive with respect to
rotationally and horizontally applied forces without locking the
support member to the rotational drive with respect to vertically
applied forces (e.g., forces parallel with the longitudinal axis of
the rotational drive). Thus, the rotational lock need not be
removed prior to lifting the spider 10 from the shaft 20, such as
during routine maintenance. Despite lack of a vertical lock, the
combined weight of the wafer holder 16 and the spider 10 is
sufficient to prevent the substrate holder 16 from shifting
vertically or lifting during processing of a substrate 18, thus
keeping the retaining member 22 engaged and inhibiting rotational
slippage
[0045] Preferably, the securing portion 32 of the retaining member
22, which protrudes outside the spider socket 14, is held by a
securing element 34 of the spider 10. In the illustrated
embodiment, the securing element 34 comprises a hook member that
secures the retaining member 22 in place by restraining outward
movement of the securing portion 32 of the retaining member 22 when
the portion 32 is rotated into the position shown. Advantageously,
the portion 32 is biased by gravity into the position shown and can
be rotated downwardly into that position after the retaining
portion 24 engages the indentation in the locked position. The
securing element 34 is configured to allow the retaining member 22
to be removed by first rotating the securing portion 32 of the
retaining member 22 in a clockwise direction, thereby freeing the
securing portion 32 of the retaining member 22 from the securing
element 34. The engaging portion 24 can then be removed, if
necessary, from the socket opening 26 by pulling the retaining
member 22 out of the socket opening 26. However, as previously
outlined, it is not necessary to remove the retaining member 22 in
order to remove the shaft 20 wafer holder 22, thus facilitating
maintenance despite the fact that the rotational locking elements
are hidden below the susceptor 16 (FIG. 1)
[0046] FIG. 2C shows a magnified view of the elbow-shaped retaining
member 22 employed in the support assembly shown in FIGS. 2A and
2B, the engaging portion 24 and the securing portion 32 being more
clearly shown. The illustrated retaining member 22 is generally
L-shaped, but it is not necessary that the engaging portion and
securing portion be perpendicular. FIG. 2D is a sectional view of
FIG. 2B, with the retaining member 22 removed for clarity.
[0047] FIGS. 3A and 3B show the elongated shaft 20 employed in
preferred embodiments of the present invention. Preferably, the
shaft indentation 30 is configured to provide a face or faces
having sufficient surface area to contact the engaged retaining
member 22 to prevent or minimize the risk of the spider 10 rotating
independently of the shaft 20. The shaft 20 has an indentation 30
in the end portion 36 of the shaft 20. Preferably, the end portion
36 of the elongated shaft 20 is tapered as shown and has a
generally curved (illustrated as conical) surface except for the
planar indentation 30. The indentation 30 is configured, when
aligned with the socket opening 26, to receive the engaging portion
24 (FIG. 2) of the retaining member 22 inserted through the side
wall 28 of the spider socket 14. The retaining member 22 thus links
the elongated shaft 20 to the spider socket 14 to minimize or
prevent rotation of the spider 10 with respect to the shaft 20.
Preferably, when in an engaged position, the retaining member 22,
which is perpendicular to the longitudinal axis of the shaft 20,
abuts a face of the shaft indentation 30. The shaft indentation 30
preferably extends vertically in a direction parallel with the
longitudinal axis of the shaft 20, thereby preventing the retaining
member 22 from independently rotating about the longitudinal axis
of the shaft 20. The spider 10 is prevented from rotating with
respect to the shaft 20. In some embodiments, the retaining member
22 also engages a lower, horizontally-extending face of the shaft
indentation 30 (i.e., the floor of the indentation 30). Preferably,
the assembly is configured to maximize the surface area of contact
between the shaft indentation 30 and the retaining member 22.
[0048] FIG. 3C shows an alternate shaft configuration employed in
certain embodiments, in which the elongated shaft 20 has three
indentations 30. The illustrated shaft 20 allows an operator to
engage the closest indentation 30 during assembly (see FIGS. 7 and
8 and corresponding text below). In alternate preferred
embodiments, the three indentations are slightly different with
respect to one another as a result of variations due to, for
example, machining imperfections, thermal expansion and/or wear
after use. As a result of these differences, in operation, the
operator may choose between indentations which, when engaged by the
retaining member, best secure the spider to the shaft with respect
to rotational forces. The three-indentation shaft 20 may be
employed in any of the embodiments of the invention disclosed
herein.
[0049] FIGS. 4A and 4B show another embodiment of the present
invention, in which a flexible retaining member 38 is employed
instead of the retaining member 22 illustrated in FIGS. 2A-2D. The
shaft 20 is shown disengaged from socket 14 for clarity. The
flexible retaining member 38 secures the shaft 20 against rotation
relative to the spider socket 14. Preferably, the retaining member
38 is cylindrical. As with the embodiment employing the
elbow-shaped retaining member 22 (shown in FIGS. 2A-2D) the
engaging portion 24 of the retaining member 38 is designed to be
inserted through the opening 26 in the side wall of the socket 14
and, when the opening 26 is aligned with the indentation 30, to
engage the shaft indentation 30 and protrude beyond the opposite
side of the spider arm 12 from which the engaging portion 24 is
inserted. However, unlike the elbow-shaped member 22 of FIGS.
2A-2D, the flexible retaining member 38 is preferably generally
straight when no forces are applied to the member 38. In addition,
the retaining member 38 can be flexed so that the securing portion
32, i.e., the end not engaging the shaft indentation 30, can be
inserted into an opening 40 in the spider arm 12.
[0050] When flexed and inserted into both openings 26 and 40 to
rotationally secure the spider 10 to the elongated shaft 30, the
flexible retaining member 38 is biased toward straightening and
therefore exerts forces in directions that are perpendicular to the
direction in which force is required to remove the retaining member
38. The retaining member 38 thereby holds the retaining member 38
in the desired secured position. As a result, the engaging portion
32 of the retaining member 38 preferably remains engaged with the
socket opening 26 and the shaft indentation 30. Although the arm
opening 40 is shown as only partially extending into arm 12, it
should be understood that the arm opening 40 may extend deeper into
or completely through the arm 12. In alternate arrangements, the
securing portion can be secured in the arm opening by a screw or by
threading the securing portion and the arm opening. The flexible
retaining member 38 is preferably selectively removed by
compressing the end portions 32 and 24 toward one another and
pulling said portions from their respective openings. In addition,
the embodiments illustrated in FIGS. 4A-4B also preferably employ
the elongated shaft 20 (shown in FIG. 4A in an unmated position
with respect to the socket 14) having a tapered end portion 36 and
an indentation 30 as shown in FIGS. 3A-3B or, in alternate
preferred embodiments, three indentations 30 as shown in FIG.
3C.
[0051] The flexible retaining member 38 is preferably constructed
of a material that allows the member 38 to flex from end to end.
The member 38 can be constructed of a number of flexible materials
suitable for use in a process chamber environment, such as metals,
plastics, and other materials or combinations of materials as will
be evident to the skilled artisan in view of the present
disclosure.
[0052] FIGS. 4C and 4D show an alternative embodiment of the
retaining member, in a flexed and a relaxed state, respectively.
Rather than being flexible from end to end, the illustrated
retaining member 42 includes a central spring portion 44 interposed
between two rigid elements 46. The spring portion 44 is shown by
cross-hatching.
[0053] FIGS. 5A and 5B illustrate a support assembly 8 employing a
retaining member 48 in accordance with yet another embodiment of
the invention. The retaining member 48 is preferably shaped to
conform to a "corner region" 50 defined as the region between two
adjacent ones of the spider arms 12, within which is located the
opening 26 in the socket 14. FIG. 5A is a bottom perspective view
of the spider 10. In one embodiment, the spider socket 14 and
opening 26 are designed to receive an extension 52 of the retaining
member 48. When the retaining member 48 is inserted into the
opening 26, the extension 52 protrudes into the interior of the
spider socket 14. Accordingly, when the shaft 20 is mated with the
socket 14 and the indentation 30 is properly aligned with the
opening 26, the extension 52 engages the indentation 30 of the
shaft 20. The retaining member 48 thereby secures the spider socket
14 with respect to the shaft 20.
[0054] With further reference to FIG. 5A, a first slot 54 is
located in one of the spider arms 12 that defines the corner region
50 and a second slot 56 is located in the other of such spider arms
12. The retaining member 48 preferably has extensions or ears 58
which, when inserted into the corresponding first and second slots
54, 56 of the spider arms 12, protrude from the opposite side of
the spider arm 12 from which the ears were inserted. Each ear 58
preferably also has an opening 60 (FIG. 5C) that is configured to
receive a locking pin 62 (FIGS. 5A, 5B and 5D) to secure the
retaining member 48 in the comer region 50. Securing the retaining
member 48 ensures that the extension 52 is properly aligned and
remains engaged with the properly aligned shaft indentation 30,
thereby preventing or minimizing rotation of the spider 10 (and
therefore of the susceptor or wafer holder 16 supported by the
spider 10) with respect to the elongated shaft 20. FIG. 5C is a
magnified view of the retaining member 48 employed in FIGS. 5A and
5B.
[0055] FIG. 5D is a magnified view one of the locking pins 62
employed in FIGS. 5A and 5B. In preferred embodiments, two locking
pins 62 are employed to secure the retaining member 48 in the comer
region 50. The locking pins 62 each have an extension 63 which is
configured to be inserted in the pin holes 60 of the retaining
member ears 58. In addition, the locking pins 62 have a top portion
61 which is larger than the diameter of the pin holes 60, so that
when the locking pin extension 63 is placed in the pin hole 60, the
locking pin 62 remains supported in place on the protruding ear 58
of the retaining member 48 (due to gravity). Specifically, the top
portion 61 prevents the locking pin 62 from sliding through the pin
hole 60.
[0056] When the retaining member 48 is properly aligned with the
comer region 50 and the socket opening 26, both ears 58 are aligned
with their respective first and second slots 54, 56. The insertion
of each ear 58 into its respective slot 54, 56, and the subsequent
insertion of the locking pins 62 into the pin holes 60, serves to
secure the retaining member 48 in place. When aligned with the
indentation of the shaft 20, the extension 52 engages the
indentation 30 and, as a result, the shaft 20, when fully inserted
into the socket 14, is rotationally secured to the spider socket 14
(FIG. 5B). As with the previously described embodiments, the spider
10 is not vertically locked with respect to the shaft 20, such that
it can be readily lifted during maintenance.
[0057] FIGS. 6A-6D illustrate a support assembly 8 in accordance
with yet another embodiment of the present invention, which employs
a retaining member 64 designed to be inserted into a slot 66 in the
spider arm 12. When in an engaged position, the retaining member 64
engages the shaft indentation 30 aided by two prongs or arms 68
that straddle the slotted spider arm 12. The spider arm slot 66 is
partially defined by a wall portion 67 (FIG. 6B) that allows the
retaining member 64 to be selectively maintained within the slot
66. The wall portion 67 defines an upper portion 69 of the slot 66,
as well as a lower or engaged portion 72. The slot 66 also extends
into the socket 14. The lower portion or engaged portion 72 is
closer to the spider socket 14 than the remainder of the slot 66.
The slot 66 is configured to hold the retaining member 64 in a
position in which the retaining member 64 can engage the shaft
indentation 30 when the shaft 20 is fully inserted into the socket
14. When an engaging portion 74 of the retaining member 64 is in
the lower portion 72 of the slot 66 as shown in FIG. 6C, the
retaining member 64 is biased by gravity into a locked position in
which the prongs 68 straddle the wall portion 67. In this position,
the retaining member 64 therefore preferably remains in an engaged
position, thereby continuing to secure the spider 10 to the shaft
with respect to rotationally applied forces. The upper and lower
interior surfaces of the slot 66, particularly where it enters the
socket 14, serve to keep the retaining member 64 from slipping
downwardly. A back wall 70 (FIG. 6B) of the wall portion 67 and the
two arms 68 that straddle the slotted spider arm 12 together hold
the retaining member 64 in an engaged position with respect to
horizontally applied forces. FIG. 6B shows the retaining member 64
in an unengaged position separate from the support assembly 8.
FIGS. 6C-6D show the retaining member 64 in an engaged position,
thereby rotationally securing the spider 10 to the shaft 20. FIG.
6D, a horizontal cross-section of FIG. 6C, further illustrates how
the arms 68 straddle the spider arm 12, and how the engaging
portion 74 engages the shaft indentation 30. FIG. 6D also
illustrates the position of the back wall 70 of the spider arm slot
66 (shown in FIG. 6B in a side view without the retaining member
inserted) with respect to the retaining member 64.
[0058] In certain preferred embodiment, the substrate holder is
configured to hold a 300 mm wafer, while in another embodiments the
substrate holder is configured to hold a 200 mm wafer.
[0059] Preferred embodiments of the present invention are
configured to couple a substrate holder support to a form of
rotational linkage, such as a shaft or other form of linkage,
preferably by linking the rotational linkage to the substrate
holder support with a linking member, so as to prevent rotational
slippage of the substrate holder support with respect to the
rotational linkage. The linking member, such as a retaining member
or locking key, is preferably configured to engage both the
rotational linkage and the substrate holder support or spider.
Preferably, the linking member, engages an opening in the substrate
holder support, such as a spider, and contacts a contact surface or
retaining surface, such as an indentation, on the rotational
linkage, e.g. a shaft. However, the skilled artisan will readily
appreciate modifications of the preferred embodiments disclosed
herein which would fall within the scope of the claims. For
example, the shaft could have an upturned integral receptor or
socket with an opening and the spider could have an integral
downward extension having the contact surface or indentation. The
skilled artisan will understand in view of the present disclosure
that, even in light of these structural modifications, the linking
member described herein would still function to prevent the
rotational slippage of the spider with respect to the shaft. In an
alternate embodiment, an integral retaining member (e.g.,
permanently installed) is employed to prevent rotational slippage.
Advantageously, the illustrated embodiments allow the ready
retrofit of existing spiders simply by machining holes into their
sockets and arms.
[0060] The retaining member used in embodiments employing a
retaining member which is preferably rigid (e.g., the retaining
member employed in FIGS. 2A-2D, 3A-3C, 5A-5D, and 6A-6D) are
preferably formed from a ceramic material. More preferably the
retaining member is quartz, while in alternate embodiments the
retaining member is formed from silicon carbide (SiC) or graphite
coated with silicon carbide.
[0061] In yet another alternate embodiment, the shaft (or
rotational drive) and the interior of the substrate holder support
socket (or rotational drive interface) are shaped to precisely fit
together (e.g., to prevent rotational slippage). For example, as
shown in FIG. 7, the shaft 20 is machined to have a non-rounded
(e.g., flat) section 73 which precisely mates with a
correspondingly machined spider socket having a shaped section 71
in order to prevent rotational slippage. In other alternate
embodiments, the shaft and socket are configured to have
corresponding shapes other than those shown in FIG. 7 (e.g.,
notched shaft and corresponding socket extension).
[0062] FIG. 8 illustrates a method of rotating a rotating susceptor
holding assembly by coupling 100 a substrate holding structure
(e.g., spider) to a rotational drive (e.g., shaft). A linking
member is inserted 110 into an opening in the substrate holding
structure, so that the linking member rotationally links the
substrate holding structure to the rotational drive, thereby
preventing the substrate holding structure from rotating
independent of a rotational source. Either the substrate holding
structure or the rotational drive are rotated 120 with respect to
one another.
[0063] In a preferred embodiment shown in FIG. 9, a shaft end
portion is inserted 200 into a socket of a substrate holder
support. The support has an opening in the wall of the socket and
the shaft end portion has an indentation. A retaining member is
inserted 210 into the opening. The shaft and the substrate holder
are then rotated 220, preferably manually, with respect to one
another about a longitudinal axis of the shaft until the opening
and the indentation together form a passage and the retaining
member drops into contact with the indentation (i.e., a first fully
engaged position). The shaft is then rotated 230 about its
longitudinal axis to thereby rotate the substrate holder support.
Advantageously, the substrate holder support can then be freely
lifted out of the first fully engaged position for replacement or
other routine maintenance.
[0064] Preferred embodiments prevent the substrate support holder
from rotating independent of the shaft. In other words, preferred
embodiments prevent rotational slippage. However, the skilled
artisan will appreciate that, even with the locking features of the
embodiments described herein, some small amount of slippage can be
caused by machining tolerances affecting the fit of the retaining
member relative to the substrate support holder and/or the shaft.
Accordingly, preventing rotational slippage and securing or locking
the substrate support holder to the shaft, as used herein, is meant
to encompass such small amounts of slippage caused by machining
tolerances.
[0065] In another preferred embodiment the linking member is
inserted after coupling the substrate holding structure to the
rotational linkage. In this embodiment, inserting the linking
member would comprise inserting an end portion of a shaft into a
socket of a support for a wafer holder, the support having an
opening in a wall of the socket, the shaft end portion having one
or more linking member contact surfaces. The shaft and support are
then rotated with respect to one another about a longitudinal axis
of the shaft until the opening and one of the one or more contact
surfaces together form a passage. The linking member is inserted
into the passage so that the linking member prevents the wafer
holder support from rotating with respect to the shaft. After the
linking member is inserted into the passage, the shaft is rotated
about its longitudinal axis to thereby rotate the wafer holder
support.
[0066] In another preferred embodiment, a method of assembling a
rotating susceptor assembly is provided. During assembly, the
substrate holding structure is coupled to a rotational linkage so
as to prevent rotational slippage of the susceptor holding
structure relative to the rotational linkage during rotation of the
substrate holding assembly. Preferably, the rotational linkage is
linked or "clocked," with respect to rotational forces, to the
substrate holding structure using a linking member which prevent
rotational slippage by engaging a hole in the substrate holding
structure and contacting a contact surface of the rotational
linkage.
[0067] In yet another preferred embodiment, a rotational linkage
and substrate holding structure, which are shaped to precisely fit
together (e.g., the assembly shown in FIG. 7), are employed. A
shaped portion of the substrate holding structure is aligned with a
correspondingly shaped section of the rotational linkage and
lowered onto the rotational linkage. As a result, the substrate
holding structure is coupled to the rotational linkage so as to
prevent rotational slippage of the susceptor holding structure
relative to the rotational linkage during rotation of the substrate
holding assembly.
[0068] Although this invention has been disclosed in the context of
certain preferred embodiments and examples, it will be understood
by those skilled in the art that the present invention extends
beyond the specifically disclosed embodiments to other alternative
embodiments and/or uses of the invention and obvious modifications
thereof. For example, the shaft could be configured to have an
integral receptor which engages an integral substrate holder
support extension. An opening would then preferably be located in
the side of the receptor and the invention would be in the
extension. Thus, it is intended that the scope of the present
invention herein disclosed should not be limited by the particular
disclosed embodiments described above, but should be determined
only by a fair reading of the claims that follow.
* * * * *