U.S. patent application number 09/756849 was filed with the patent office on 2002-07-11 for spatula for separation of thinned wafer from mounting carrier.
Invention is credited to De, Bhola, Grey, Mark Spencer.
Application Number | 20020088556 09/756849 |
Document ID | / |
Family ID | 25045317 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020088556 |
Kind Code |
A1 |
De, Bhola ; et al. |
July 11, 2002 |
SPATULA FOR SEPARATION OF THINNED WAFER FROM MOUNTING CARRIER
Abstract
A wafer removing spatula has a handle connected to a tray. A
shaft of the handle is provided with a pair of support guides and
the tray is provided with a wafer support surface which rests on a
tray support surface. The support guides and the tray support
surface are configured and dimensioned to ensure that the wafer
support surface is substantially parallel to the upper surface of a
base plate on which both the support guides and the tray support
surface rest. A front edge of the wafer support surface is provided
with a bevel to facilitate lifting a wafer from a wafer carrier
surface. The height of the lowermost portion of the front edge is
approximately the same as the height of a wafer carrier placed on
the base plate. During operation, the spatula is moved on the base
plate towards the carrier with the wafer mounted thereon. The front
edge of the spatula eases just above the upper surface of the wafer
carrier such that the beveled edge creates and then enters a
separation gap between the wafer and the wafer carrier, thereby
causing the wafer to separate from the wafer carrier and climb onto
the wafer support surface.
Inventors: |
De, Bhola; (Congers, NY)
; Grey, Mark Spencer; (Somerset, NJ) |
Correspondence
Address: |
PENNIE & EDMONDS LLP
1667 K STREET NW
SUITE 1000
WASHINGTON
DC
20006
|
Family ID: |
25045317 |
Appl. No.: |
09/756849 |
Filed: |
January 10, 2001 |
Current U.S.
Class: |
156/750 ;
156/761 |
Current CPC
Class: |
Y10T 156/11 20150115;
Y10T 156/19 20150115; Y10T 156/1184 20150115; H01L 21/68707
20130101; Y10T 156/1961 20150115; Y10S 156/941 20130101 |
Class at
Publication: |
156/584 |
International
Class: |
B32B 035/00 |
Claims
What is claimed is:
1. A wafer removing spatula comprising: a handle having a shaft
provided with a first and a second end, the shaft having slidably
mounted thereon at least one support guide between said first and
second ends, the at least one support guide having a bottom post
surface configured and dimensioned to allow longitudinal movement
of said spatula along its shaft, when said bottom post surface is
fixed to a mounting surface; a tray connected to the first end of
the handle, the tray including a substantially planar wafer support
surface defining a plane, an upper tray boundary member projecting
above the wafer support surface and partially surrounding a
perimeter thereof, and a lower tray support member configured and
dimensioned to retain the wafer support surface substantially
parallel to a mounting surface on which said lower tray support
member rests, as the spatula is moved longitudinally along its
shaft; and a thermally insulating grip connected to the second end
of said shaft member, the thermally insulating grip having an
abutment surface which extends below the plane of the wafer support
surface, when the spatula is oriented such that the wafer support
surface is horizontal.
2. The spatula according to claim 1, wherein said wafer support
surface, upper tray boundary member, lower tray support member and
said shaft are all formed from a same material.
3. The spatula according to claim 2, wherein said material is
stainless steel.
4. The spatula according to claim 1, comprising a pair of spaced
apart support guides arranged along said shaft, each support guide
being provided by with a corresponding bottom post surface.
5. The spatula according to claim 1, wherein a front end of the
wafer support surface is provided with first and second operative
edges converging in direction away from the handle member and
meeting at an apex.
6. The spatula according to claim 5, wherein the first and second
operative edges are provided with a beveled edge configured and
dimensioned to facilitate lifting a wafer from a carrier.
7. The spatula according to claim 5, wherein the apex is rounded,
having a radius of curvature between 75-85 mm.
8. The spatula according to claim 1, wherein a front end of the
wafer support surface is provided with at least one beveled edge
configured and dimensioned to facilitate lifting a wafer from a
carrier.
9. The spatula according to claim 1, further comprising a plurality
of screws joining together the wafer support surface, the upper
tray boundary member, and the lower tray support member.
10. A wafer removing assembly comprising: a base plate having a
substantially planar mounting surface; and a wafer removing spatula
comprising: a handle having a shaft provided with a first and a
second end, the shaft having slidably mounted thereon at least one
support guide between said first and second ends, the at least one
support guide having a bottom post surface configured and
dimensioned to allow longitudinal movement of said spatula along
its shaft, when said bottom post surface is fixed to said
substantially planar mounting surface; a tray connected to the
first end of the handle, the tray including a substantially planar
wafer support surface defining a plane, an upper tray boundary
member projecting above the wafer support surface and partially
surrounding a perimeter thereof, and a lower tray support member
configured and dimensioned to retain the wafer support surface
substantially parallel to said substantially planar mounting
surface, as the spatula is moved longitudinally along its shaft;
and a thermally insulating grip connected to the second end of said
shaft member, the thermally insulating grip having an abutment
surface which extends below the plane of the wafer support surface,
when the spatula is oriented such that the wafer support surface is
horizontal.
11. The wafer removing assembly according to claim 10, further
comprising: an upstanding stop provided at a first end of said base
plate, the upstanding stop having a height taller than a height of
said wafer support surface.
Description
RELATED APPLICATIONS
[0001] NONE
TECHNICAL FIELD
[0002] The present invention is directed to the field of equipment
and accessories for processing semiconductor wafers. More
particularly, it is directed to a device which is used to
facilitate demounting a semiconductor wafer which has been
adhesively mounted to a carrier disc used for support during a
manufacturing operation.
BACKGROUND OF THE INVENTION
[0003] During semiconductor manufacture, a semiconductor wafer is
placed on a carrier which provides mechanical support to the wafer,
as the wafer is sent through various processing steps. An adhesive
may be used to bond the wafer to the carrier to provide support
while preventing slippage. Once the processing steps are over, a
mechanical device may be used to debond and/or demount the wafer
from the carrier. The prior art includes a number of devices that
can be used to lift a wafer from a surface.
[0004] U.S. Pat. No. 5,479,108 to Cheng discloses a wand member
attached to an end of a mechanical wafer pick. The wafer pick
travels in a longitudinal direction in a plane substantially
parallel to the surface of a chuck on which a wafer rests. The wand
member slides under a wafer and rises to lift the wafer off of the
surface of a chuck.
[0005] U.S. Pat. Nos. 4,984,954 and 4,867,631 to Warenback et al.
disclose a spatula for wafer transport. The spatula contains a
single major recess for receiving a wafer. Adjacent one edge of the
recess is a shoulder for locating the wafer in the sequence of
operations for loading the spatula. As a result of the sequence,
the center of the wafer is held at a predetermined, known
location.
[0006] U.S. Pat. No. 4,971,512 to Lee et al. discloses a transport
device for handling wafers of different diameters. A robotic arm is
equipped with a fork-shaped wafer support board and an arm slide
movable relative to the robotic arm. The fork-shaped end of the
support board is provided with fixed pins on one side to support
wafers and on another side with plate springs carrying pins which
can be depressed by the weight of a wafer to accommodate larger
size wafers. The device permits wafers of different diameters
accurately and safely to be transferred from its center to a
predetermined station without the need for changing the wafer
support board or correction of the robotic arm.
[0007] U.S. Pat. No. 4,875,824 to Moe et al discloses a transfer
mechanism to pick up a wafer from one location, lift it, transfer
it laterally, lower it and later deposit it another location. A
horizontal feedscrew mounted in a stationary base controls
horizontal reciprocation of a transverse housing. A vertical
feedscrew mounted in the transverse housing controls vertical
reciprocation of a second housing. Supported by the second housing
are one or more lifts. Each lift has guide rods fixed relative to
the second housing and a stop on its lower end. Parallel and
adjacent the guide rods is a reciprocating rod carrying a gripper
on its lower end. At the end of the vertical movement of the second
housing the reciprocating rod moves the gripper away from the stop
so that a wafer may rest on the guide rods. As the second housing
moves up, the gripper clamps the wafer against the stop. Motors
drive the feedscrews to lift the wafer, move it transversely and
lower it. As it reaches the end of its lowering movement, the wafer
is unclamped.
[0008] U.S. Pat. No. 4,619,573 to Rathmann et al. discloses a rail
guided, magnetically driven shuttle plate. Baffles serve to isolate
the particle producing portions of the mechanism from the wafers.
The major drive components are located inside the rails and outside
the vacuum containment system. A pin lift apparatus located on the
reactor chucks serves to remove and replace wafers on the shuttle
plate.
[0009] U.S. Pat. No. 4,496,180 to Hillman et al. discloses a vacuum
operated apparatus is for releasably grasping and transporting a
thin solid object or article (e.g. silicon semiconductor wafer).
The apparatus has two fixed rigid arms joined together at their
rear end to define a gap therebetween having an open end and a
closed end wherein the upper arm directs the thin solid object into
the gap and toward the lower arm having a port communicating with
the gap and an enclosed passage way connected to a vacuum source.
The device is provided with a plate fixed to the bottom of the
lower arm. Silicon semiconductor wafers may be grasped and
transported with the apparatus and more especially silicon
semiconductor wafers can be deposited onto and removed from the
surface of a barrel type susceptor of an epitaxial reactor with
enhanced ease and reduced danger of scratching and breaking the
wafer.
SUMMARY OF THE INVENTION
[0010] The wafer demount fixture of the present invention comprises
a hand-held spatula specially configured to remove a brittle wafer
from a carrier plate. The spatula is provided with at least one
support guide slidably mounted thereon, the support guide
permitting longitudinal movement of the spatula, when the support
guide is fixed to a mounting surface. As the spatula moves in a
longitudinal direction, a front edge of a wafer support surface of
the spatula eases under a wafer, thereby lifting the wafer from a
supporting carrier in a manner which minimizes chances of breaking
the wafer. A handle member of the spatula is provided with a grip
having an abutment surface configured to abut a base plate on which
the spatula is mounted, thereby preventing the spatula from being
moved too far in the direction of the wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention can better be understood through the
attached figures in which:
[0012] FIG. 1 shows a plan view of a spatula, semiconductor wafer
and carrier in accordance with the present invention, prior to a
demounting step;
[0013] FIG. 2a shows a side view of the spatula, wafer and carrier
of FIG. 1;
[0014] FIG. 2b shows the detail indicated in FIG. 2a;
[0015] FIG. 3 shows a plan view of the spatula, semiconductor wafer
and carrier of FIG. 1 during the demounting step;
[0016] FIG. 4 shows a side view of the spatula, wafer and carrier
of FIG. 3;
[0017] DETAILED DESCRIPTION OF THE INVENTION
[0018] FIGS. 1-4 show a plan view and a side view of a spatula 100
in accordance with the present invention resting on a base plate
200. The spatula 100 includes an elongated handle 102 connected at
a first handle end to a tray 104.
[0019] The base plate 200, which is preferably formed from aluminum
is provided with an mounting surface 202 on which the spatula 100
may rest or slide, as operated by the user. The base plate has a
thickness t1 which, preferably is between 1.0-2.0 inches and more
preferably is about 1.5 inches. The length 11 of the base plate
preferably is about 22 inches.
[0020] A first end of the base plate is provided with an upstanding
base plate stop 204 having a height h4 which, in a preferred
embodiment is between 1.75-2.25 mm, and more preferably is about 2
mm. The stop 204 has a concave inner surface 206 which
substantially matches the outer contour of the carrier 300. In a
preferred embodiment, the concave inner surface 206 of the stop has
a radius of curvature of between 75-85 mm, and more preferably
between 79-80 mm, to accommodate a carrier having a like radius of
curvature.
[0021] The handle 102 is provided with a shaft 106 and a thermally
insulating grip 110 at a second handle end thereof. Preferably, the
shaft 106 and the grip 110 have circular cross-sections, with the
shaft 106 having a diameter t3 of about 0.25 inches and the grip
110 having a diameter t4 of about 3/4 inches. The grip preferably
is formed from bakelite, but can be formed from any thermally
insulating material. When used in conjunction with the base plate,
the lowermost portion of the grip 110 extends below the upper
mounting surface 202 of the base plate. When the spatula is pushed
in the direction of the base plate stop 204, the lowermost portion
of the grip 110 abuts a back abutment side surface 208 formed on
the baseplate, thereby preventing the apex 128 from running into
the stop 204 and thus damaging the front edges of the wafer support
surface 112.
[0022] As seen in the figures, the shaft 106 passes through a pair
of spaced apart support guides 108a, 108b. Each of the support
guides has a width of about 3/8 inches along the shaft 106,
although other widths may also be suitable. As seen from FIGS. 1-4,
the support guides each have a substantially square cross-section
with a substantially flat bottom guide surface 109a, 109b, which
abuts the upper mounting surface 202 of the base plate 200 to
thereby support the handle end of the spatula 100 such that the
shaft 106 and the wafer support surface 112 are substantially
parallel to the upper mounting surface 202 of base plate 200. The
clearance hi between the handle shaft 106 and the upper mounting
surface 202 of the base plate is approximately 1.5 mm, although
this figure may be varied somewhat without departing from the
present invention.
[0023] As best seen in FIGS. 1 and 3, the first support guide 108a
is spaced apart by a variable distance d1 from the tray and the
second support guide 108b is spaced apart from the first support
guide by a distance d2. Thus, the support guides are mounted on the
base plate upper mounting surface 202 so as to permit longitudinal
motion of the spatula along its shaft, and towards and away from
the wafer. The support guides may thus be slidably fixed to the
shaft and further be provided with mounts (not shown) to secure
them to the upper surface 202. It should also be noted that while a
pair of spaced apart support guides are shown, one may instead use
a single, elongated support guide which is properly aligned, when
mounted to the upper surface 202.
[0024] The tray 104 includes a substantially planar wafer support
surface 112, a U-shaped upper tray boundary member 114 having a
height h2 and a U-shaped lower tray support member 116 having a
height h3. As seen in FIGS. 1 and 2, the thickness t2 of the
U-shaped tray members and the heights h2 and h3 are sufficient to
provide the planar wafer support surface 112 with structural
rigidity so as to prevent significant torsional deformation. In a
preferred embodiment t2 is 1.0-1.5 cm in thickness, h2 is between
5-7.5 mm in height and h3 is approximately 1.25-1.75 mm in height,
although other thicknesses and heights may also suffice. The
U-shaped upper tray boundary member 114 comprises upstanding
boundary walls including parallel first 118a and second 118b side
walls and a back wall 120. The U-shaped lower tray support member
116 has a similar construction and is provided with a lower tray
support surface 117. It should be noted here that instead of having
unitary construction, the U-shaped tray boundary members 114, 116
may each comprise individual side and back walls. Regardless of
their construction, screws 122 or other fasteners are preferably
used to fasten the upper and lower members with the wafer support
surface 112.
[0025] The wafer support surface 112 preferably is formed as a
thin, rigid membrane between 2-4 mil in thickness. The wafer
support surface 112 has a leading end portion 124 comprising first
and second operative front edges 126a, 126b which extend outwardly
in a direction away from the handle 102 to meet at a rounded apex
128. The wafer support surface preferably is thicker near the
operative front edges and thinner near its central portion. As seen
in FIG. 2b, the operative front edges, especially at the apex, are
provided with a bevel 130 having an angle .alpha. which preferably
is between 20-40.degree., more preferably is between
25.degree.-35.degree. and most preferably is about 30.degree.. The
bevel 130 is used to help the front of the wafer support surface
112 demount the wafer 310 from the carrier 300 by easing under the
bottom surface of the wafer, thereby lifting an edge of the wafer
thereonto.
[0026] The interior width of the wafer support surface 112 in the
region between the side walls 118a, 118b has a dimension w1, which
is sufficient to accommodate the width of a semiconductor wafer of
standard size. Thus, in the spatula designed to hold an 8 inch
wafer, w1 preferably is no greater than about 8.5 inches.
Similarly, in a spatula designed to hold 12 inch wafers, w1
preferably is no greater than about 12.5 inches. It is understood,
however, that w1 may take on other lengths for either size wafer.
The interior length w2 of the wafer support surface is large enough
to accommodate the corresponding size wafer.
[0027] The shaft 106, the wafer support surface 112, and the upper
114 and lower 116 U-shaped members are all preferably formed from
the same material so that each member undergoes a substantially
similar expansion or contraction in response to temperature
changes. Preferably, the material is non-magnetic, non-brittle, and
can withstand temperatures up to 150.degree. C. In a preferred
embodiment, these members are formed from stainless steel, although
other materials may also be used.
[0028] A semiconductor wafer 310, such as a GaAs wafer, held on a
wafer carrier 300 by an adhesive is processed through a number of
steps. Once wafer processing is completed, the wafer must be
demounted from the wafer carrier 300. For this, the wafer carrier
300 is placed on the base plate 200 and the temperature of the base
plate 200 is then is raised to soften the adhesive between the
wafer carrier 300 and the wafer 310. The height of the lowermost
portion of the front edges of the wafer support surface 112 is
approximately the same as the height of the wafer carrier 300
placed on the base plate. This is accomplished by providing that
the height h3 of lower U-shaped member 116 is approximately the
same as the height of the wafer carrier 300 relative to said
substantially planar upper surface 202. The user of the spatula 100
then uses the thermally insulated grip 110 to push the spatula 100
towards the carrier 300. The front edges 126a, 126b of the spatula
ease just above the upper surface of the wafer carrier 300 such
that the beveled edge 130 first opens, and then enters, a
separation gap between the wafer 310 and the wafer carrier 300.
This causes the wafer 310 to separate from the wafer carrier 300
and climb onto the wafer support surface 112 as shown in FIGS. 3
and 4. The lifted wafer can then be removed by a vacuum wand or
another suitable method known to those skilled in the art.
[0029] Furthermore, the height h4 of the base plate stop 204 is
taller than a corresponding height of said wafer support surface
112 relative to said substantially planar upper surface 202, when
the spatula is placed on the base plate 200. Thus, base plate stop
204 prevents the spatula from pushing the carrier 300 off of the
base plate, while the stop's concave surface helps prevent damage
to the carrier's side.
[0030] Finally, while the above invention has been described with
reference to certain preferred embodiments, it should be kept in
mind that the scope of the present invention is not limited to
these. One skilled in the art may find variations of these
preferred embodiments which, nevertheless, fall within the spirit
of the present invention, whose scope is defined by the claims set
forth below.
* * * * *