U.S. patent application number 10/414044 was filed with the patent office on 2003-09-25 for semiconductor wafer assembly and machining apparatus having chuck tables for holding the same.
Invention is credited to Arai, Kazuhisa, Takahashi, Toshiaki.
Application Number | 20030181150 10/414044 |
Document ID | / |
Family ID | 18666205 |
Filed Date | 2003-09-25 |
United States Patent
Application |
20030181150 |
Kind Code |
A1 |
Arai, Kazuhisa ; et
al. |
September 25, 2003 |
Semiconductor wafer assembly and machining apparatus having chuck
tables for holding the same
Abstract
A semiconductor wafer assembly is constituted such that the back
surface of a tape is stuck to the surface of a frame and a
semiconductor wafer is stuck to the surface of the tape. A
machining apparatus has chuck tables for supporting the
semiconductor wafer assembly, and each of the chuck tables has a
semiconductor wafer placing surface for supporting the back surface
of the tape to which the semiconductor wafer is stuck and an
annular frame placing surface for supporting the back surface of
the frame, formed, in the outer peripheral side of the
semiconductor wafer mounting surface, at a position below the
semiconductor wafer placing surface with a level difference
therebetween.
Inventors: |
Arai, Kazuhisa; (Tokyo,
JP) ; Takahashi, Toshiaki; (Tokyo, JP) |
Correspondence
Address: |
SMITH, GAMBRELL & RUSSELL, LLP
1850 M STREET, N.W., SUITE 800
WASHINGTON
DC
20036
US
|
Family ID: |
18666205 |
Appl. No.: |
10/414044 |
Filed: |
April 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10414044 |
Apr 16, 2003 |
|
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|
09854495 |
May 15, 2001 |
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Current U.S.
Class: |
451/285 ;
451/388; 451/41 |
Current CPC
Class: |
H01L 21/6836 20130101;
B24B 41/061 20130101; B25B 11/005 20130101; H01L 21/67132 20130101;
B24B 7/228 20130101; H01L 2221/68327 20130101 |
Class at
Publication: |
451/285 ; 451/41;
451/388 |
International
Class: |
B24B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2000 |
JP |
2000-162287 |
Claims
What is claimed is:
1. A semiconductor wafer assembly consisting of an annular frame, a
tape mounted to the frame and a semiconductor wafer stuck to the
tape, wherein the back surface of the tape is stuck to the surface
of the frame and the semiconductor wafer is stuck to the surface of
the tape.
2. The semiconductor wafer assembly of claim 1, wherein an adhesion
layer is formed in at least an area where the semiconductor wafer
is arranged, of the surface of the tape and an adhesion layer is
also formed in an area in contact with the surface of the frame, of
the back surface of the tape.
3. The semiconductor wafer assembly of claim 1, wherein a cutout
corresponding to a cutout showing the crystal orientation of the
semiconductor wafer is formed in an outer peripheral portion of the
frame and the both cutouts are aligned with each other.
4. A semiconductor wafer assembly consisting of an annular frame, a
tape mounted to the frame, a semiconductor wafer stuck to the
surface of the tape and a fixing ring for fixing the periphery
portion of the tape to the frame, wherein the annular frame
consists of an annular frame portion and an annular mounting
portion that projects upward from the inner peripheral portion of
the frame portion, and the tape is placed to the surface of the
mounting portion and the fixing ring is fitted onto the outer
circumferential portion of the mounting portion to sandwich the
periphery portion of the tape between the outer peripheral surface
of the mounting portion and the inner peripheral surface of the
fixing ring.
5. The semiconductor wafer assembly of claim 4, wherein a cutout
corresponding to a cutout showing the crystal orientation of the
semiconductor wafer is formed in an outer circumferential portion
of the frame and the both cutouts are aligned with each other.
6. A machining apparatus comprising chuck tables having a placing
surface for suction-holding a semiconductor wafer assembly and a
machining means for machining the semiconductor wafer of the
semiconductor wafer assembly suction-held on each of the chuck
tables, wherein the semiconductor wafer assembly consists of an
annular frame, a tape mounted to the frame and a semiconductor
wafer stuck to the surface of the tape, and each of the chuck
tables has a semiconductor wafer placing surface for supporting the
back surface of the tape to which the semiconductor wafer is stuck
and an annular frame placing surface for supporting the back
surface of the frame, formed, in the outer peripheral side of the
semiconductor wafer placing surface, at a position below the
semiconductor wafer placing surface with a level difference
therebetween.
7. The machining apparatus of claim 6, wherein the level difference
between the semiconductor wafer placing surface and the frame
placing surface is equivalent to the thickness of the frame.
8. The machining apparatus of claim 6, wherein the suction ports of
communication paths connected to a suction source are formed in the
frame placing surface.
9. The machining apparatus of claim 6, wherein the machining means
is a grinding means for grinding the semiconductor wafer of the
semiconductor wafer assembly.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a semiconductor wafer
assembly to be held on a chuck table when a semiconductor wafer is
to be machined, and to a machining apparatus having chuck tables
for holding the same.
DESCRIPTION OF THE PRIOR ART
[0002] As known to people of ordinary skill in the art, in a
semiconductor device production process, a substantially disk-like
semiconductor wafer is divided into individual pellets to form
semiconductor chips. To improve the heat radiation properties of
the semiconductor chip, the semiconductor chip is desirably made as
thin as possible. Also to enable the downsizing of a portable
telephone, smart card and personal computer in which a large number
of semiconductor chips are used, the semiconductor chip is
desirably made as thin as possible. To this end, prior to the
semiconductor wafer is divided into pellets, the back surface of
the semiconductor wafer is ground to machine it to have a
predetermined thickness. In a grinding machine for grinding the
back surface of the semiconductor wafer, the semiconductor wafer as
a workpiece is suction-held on a chuck table, and the back surface
of the semiconductor wafer whose top surface is suction-held on the
chuck table is ground by a grinding means.
[0003] When the semiconductor wafer is thus ground up to a
thickness of 100 .mu.m or less, for example, the rigidity of the
semiconductor wafer lowers and consequently, flexure occurs in the
entire semiconductor wafer, thereby making it difficult to
transport and store in a cassette the semiconductor wafer. Further,
in a so-called "pre-dicing" production method that dicing grooves
having a predetermined depth from the surface are in advance formed
by a dicing machine and then, the back surface of the semiconductor
wafer is finished to have a thickness of about 50 .mu.m by grinding
it to divide the semiconductor wafer into chips, the ground
semiconductor wafer does not fall apart into chips owing to the
function of a protective tape stuck to the surface side of the
semiconductor wafer but it does not have rigidity at all as a
semiconductor wafer, thereby making it extremely difficult to
transport the semiconductor wafer after grinding.
[0004] To make it easy to transport and store in a cassette the
semiconductor wafer after grinding, it is conceivable that a
semiconductor wafer assembly is constructed by mounting a
semiconductor wafer on a frame by a tape like a case where dicing
is carried out, for example, and the semiconductor wafer assembly
in this state is ground and transported. However, the semiconductor
wafer assembly which is used for dicing machining is constituted
such that a tape is stuck to the back surface of an annular frame
and a semiconductor wafer is stuck to the top surface of the tape
so that the semiconductor wafer and the frame are arranged on the
same plane. Therefore, there is a problem that as the frame is
existent on the side of the semiconductor wafer, a grinding wheel
interferes with the frame at the time when the semiconductor wafer
is ground.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide a
semiconductor wafer assembly which makes it easy to transport a
semiconductor wafer after machining and prevents a member other
than the semiconductor wafer from interfering with a machining tool
during machining, and a machining apparatus having chuck tables for
holding the semiconductor wafer assembly.
[0006] To attain the above object, according to the present
invention, there is provided a semiconductor wafer assembly
consisting of an annular frame, a tape mounted to the frame and a
semiconductor wafer stuck to the tape, wherein
[0007] the back surface of the tape is stuck to the surface of the
frame, and the semiconductor wafer is stuck to the surface of the
tape.
[0008] An adhesion layer is formed in at least an area where the
semiconductor wafer is arranged, of the surface of the tape and an
adhesion layer is also formed in an area which sticks to the
surface of the frame, of the back surface of the tape. A cutout
corresponding to a cutout showing the crystal orientation of the
semiconductor wafer is formed in an outer circumferential portion
of the frame and the both cutouts are aligned with each other.
[0009] According to the present invention, there is provided a
semiconductor wafer assembly consisting of an annular frame, a tape
mounted to the frame, a semiconductor wafer stuck to the surface of
the tape and a fixing ring for fixing the periphery portion of the
tape to the frame, wherein
[0010] the annular frame consists of an annular frame portion and
an annular mounting portion that projects upward from the inner
peripheral portion of the frame portion, and
[0011] the tape is placed to the surface of the mounting portion,
the fixing ring is fitted onto the outer circumferential portion of
the mounting portion to sandwich the periphery portion of the tape
between the outer peripheral surface of the mounting portion and
the inner peripheral surface of the fixing ring.
[0012] A cutout corresponding to a cutout showing the crystal
orientation of the semiconductor wafer is formed in an outer
circumferential portion of the frame portion of the frame and the
both cutouts are aligned with each other.
[0013] According to the present invention, there is provided a
machining apparatus comprising chuck tables having a placing
surface for suction-holding a semiconductor wafer assembly and a
machining means for machining the semiconductor wafer of the
semiconductor wafer assembly suction-held on the chuck tables,
wherein
[0014] the semiconductor wafer assembly consists of an annular
frame, a tape mounted to the frame and a semiconductor wafer stuck
to the surface of the tape, and
[0015] each of the chuck tables has a semiconductor wafer placing
surface for supporting the back surface of the tape to which the
semiconductor wafer is stuck and an annular frame placing surface
for supporting the back surface of the frame, formed, on the outer
peripheral side of the semiconductor wafer placing surface, at a
position below the semiconductor wafer placing surface with a level
difference therebetween.
[0016] The level difference between the semiconductor wafer placing
surface and the frame placing surface is desirably equivalent to
the thickness of the frame. The suction ports of communication
paths connected to a suction source are desirably formed in the
frame placing surface. The above machining means is a grinding
means for grinding the semiconductor wafer of the semiconductor
wafer assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of a semiconductor wafer
assembly constructed according to an embodiment of the present
invention;
[0018] FIG. 2 is a sectional view cut on A-A of FIG. 1;
[0019] FIG. 3 is a perspective view, in a disassembled way, of the
constituent members of the semiconductor wafer assembly shown in
FIG. 1;
[0020] FIG. 4 is a perspective view of a semiconductor wafer
assembly constructed according to another embodiment of the present
invention;
[0021] FIG. 5 is a sectional view cut on B-B of FIG. 4;
[0022] FIG. 6 is a perspective view, in a disassembled way, of the
constituent members of the semiconductor wafer assembly shown in
FIG. 4;
[0023] FIG. 7 is a perspective view of a surface grinding machine
as a machining apparatus constructed by the present invention;
[0024] FIG. 8 is a perspective view of an embodiment of a chuck
table mounted in the surface grinding machine shown in FIG. 7;
[0025] FIG. 9 is a sectional view showing a state where the
semiconductor wafer assembly shown in FIGS. 1 to 3 is held on the
chuck table shown in FIG. 8; and
[0026] FIG. 10 is a sectional view of another embodiment of a chuck
table mounted in the surface grinding machine shown in FIG. 7 and
shows a state where it holds the semiconductor wafer assembly shown
in FIGS. 4 to 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] A semiconductor wafer assembly and a grinding machine
constructed according to preferred embodiments of the present
invention will be described in detail with reference to the
accompanying drawings hereinafter.
[0028] FIG. 1 is a perspective view of a semiconductor wafer
assembly constructed according to a preferred embodiment of the
present invention, FIG. 2 is a sectional view cut on A-A of FIG. 1,
and FIG. 3 is a perspective view, in a disassembled way, of the
constituent members of the semiconductor wafer assembly shown in
FIG. 1. The semiconductor wafer assembly 2 of the illustrated
embodiment consists of an annular frame 21, a tape 22 mounted to
the frame 21 and a semiconductor wafer 23 stuck to the tape 22. The
annular frame 21 is formed from a thin plate as thick as about 1
mm, that is made from stainless steel or the like, for example. The
tape 22 is formed in a circular form from an appropriate resin
film, an adhesion layer 221 is formed on the surface side (upper
side in FIG. 2) of the tape 22 and an adhesion layer 222 is formed
on the back side (lower side in FIG. 2) of the periphery portion of
the tape 22. The adhesion layer 222 on the back side (lower side in
FIG. 2) of the periphery portion of the thus constructed tape 22 is
stuck to the surface (upper side in FIG. 2) of the above frame 21.
The semiconductor wafer assembly 2 is constructed by sticking the
semiconductor wafer 23 to the adhesion layer 221 on the surface of
the tape 22 of which the back surface of the peripheral portion is
stuck to the surface of the annular frame 21. At this point, the
adhesion layer to be formed on the surface of the tape 22 may be
formed in at least an area where the semiconductor wafer 23 is
arranged. The adhesion layer 222 formed on the back surface of the
periphery portion of the tape 22 is not always necessary. In this
case, an adhesion layer is formed on the surface of the frame 21 to
stick the back surface of the periphery portion of the tape 22
thereto. A cutout 21a corresponding to a cutout 23a showing a
crystal orientation of the semiconductor wafer 23 is formed at a
predetermined position of an outer circumferential portion of the
frame 21. Therefore, when the semiconductor wafer 23 is to be
mounted on the surface of the tape 22 stuck to the frame 21, it is
mounted at a position where the cutout 23a formed in the
semiconductor wafer 23 is aligned with the cutout 21a formed in the
frame 21, thereby making it possible to confirm the crystal
orientation of the semiconductor wafer 23 in the
transportation.
[0029] A semiconductor wafer assembly according to another
embodiment will be described with reference to FIGS. 4 to 6.
[0030] The semiconductor wafer assembly 3 of this embodiment
consists of an annular frame 31, a tape 32 mounted to the frame 31,
a semiconductor wafer 33 stuck to the tape 32 and an annular fixing
ring 34 for fixing the tape 32 to the frame 31. The annular frame
31 consists of an annular frame portion 311 and an annular mounting
portion 312 projecting upward from the inner peripheral portion of
the frame portion 311 and is made from a metal material such as
stainless steel. The tape 32 is formed in a circular form from an
appropriate resin film, and an adhesion layer 321 is formed on the
surface (upper side in FIG. 5) of the tape 32. The outer diameter
of the tape 32 is made larger than the outer diameter of the
annular mounting portion 312 constituting the above annular frame
31 by a size corresponding to the height of the mounting portion
312. The semiconductor wafer 33 is stuck to the adhesion layer 321
on the surface of the tape 32. The above annular fixing ring 34 has
an inner diameter slightly larger than the outer diameter of the
annular mounting portion 312 constituting the above annular frame
31, and is made from a metal material such as stainless steel, for
example. The tape 32 is placed on the surface side (upper side) of
the mounting potion 312 constituting the above annular frame 31,
and the fixing ring 34 is fitted onto the outer circumferential
portion of the mounting portion 312 to sandwich the periphery
portion of the tape 32 between the outer peripheral surface of the
mounting portion 312 and the inner peripheral surface of the fixing
ring 34, thereby making it possible to fix the tape 32 to the frame
31. Since the tape 32 is sandwiched between the mounting portion
312 of the frame 31 and the fixing ring 34, an adhesion layer does
not need to be formed on the back surface of the tape 32. A cutout
311a corresponding to a cutout 33a showing the crystal orientation
of the semiconductor wafer 33 is formed at a predetermined position
of an outer circumferential portion of the frame portion 311
constituting the annular frame 31. Therefore, the semiconductor
wafer 33 is mounted at a position where the cutout 33a formed in
the semiconductor wafer 33 is aligned with the cutout 311a, thereby
making it possible to confirm the crystal orientation of the
semiconductor wafer 33 in the transportation.
[0031] A description is subsequently given of a grinding machine
for grinding the semiconductor wafer 23 by holding the
semiconductor wafer assembly 2 as shown in FIG. 1 with reference to
FIG. 7 and FIG. 8.
[0032] The grinding machine of the illustrated embodiment comprises
a substantially rectangular parallelepiped housing 4. A static
support plate 6 is provided upright at a right upper end of the
housing 4 in FIG. 7. Two pairs of guide rails 7,7 and 8,8 extending
in a vertical direction are provided on the inside surface of the
static support plate 6. A rough-grinding unit 10 as a
rough-grinding means is mounted to one pair of guide rails 7,7 in
such a manner that it can move in an up and down direction, and a
finish-grinding unit 12 as a finish-grinding means is mounted to
the other pair of guide rails 8,8 in such a manner that it can move
in an up and down direction.
[0033] The rough-grinding unit 10 comprises a unit housing 101, a
grinding wheel 102 rotatably attached to the lower end of the unit
housing 101, a rotary drive unit 103, mounted to the upper end of
the unit housing 101, for rotating the grinding wheel 102 in a
direction indicated by an arrow, and a movable base 104 mounting
the unit housing 101. To-be-guide rails 105,105 are provided on the
movable base 104 and movably fitted to guide rails 7,7 provided on
the above static support plate 6 so that the rough-grinding unit 10
is supported movably in an up and down direction. The
rough-grinding unit 10 of the illustrated embodiment comprises a
feeding unit 11 for moving the above movable base 104 along the
guide rails 7,7 to adjust the cutting depth of the grinding wheel
102. The feeding unit 11 comprises a male screw rod 111 which is
rotatably provided in an up and down direction in parallel to the
guide rails 7,7 and supported to the above static support plate 6,
a pulse motor 112 for rotary-driving the male screw rod 111 and an
female screw block (not shown) that is mounted on the movable base
104 and meshed with the male screw rod 111. The male screw rod 111
is driven in a forward direction or reverse direction by the pulse
motor 112 to move the rough-grinding unit 10 in an up and down
direction.
[0034] The above finish-grinding unit 12 has the same constitution
as that of the rough-grinding unit 10. That is, it comprises a unit
housing 121, a grinding wheel 122 rotatably attached to the lower
end of the unit housing 121, a rotary drive unit 123, attached to
the upper end of the unit housing 121, for rotating the grinding
wheel 122 in a direction indicated by an arrow, and a movable base
124 mounting the unit housing 121. To-be-guide rails 125,125 are
provided on the movable base 124, and movably fitted to guide rails
8,8 provided on the above static support plate 6 so that the
finish-grinding unit 12 is supported movably in an up and down
direction. The finish-grinding unit 12 of the illustrated
embodiment comprises a feeding unit 13 for moving the above movable
base 124 along the guide rails 8,8 to adjust the cutting depth of
the grinding wheel 122. The feeding unit 13 has substantially the
same constitution as the above feeding means 11. That is, the
feeding unit 13 comprises a male screw rod 131 which is rotatably
provided in an up and down direction in parallel to the guide rails
8, 8 and supported to the above static support plate 6, a pulse
motor 132 for rotary-driving the male screw rod 131 and a female
screw block (not shown) mounted on the movable base 124 and fitted
to the male screw rod 131. The male screw rod 131 is driven in a
forward direction or reverse direction by the pulse motor 132 to
move the finish-grinding unit 12 in an up and down direction.
[0035] The grinding machine of the illustrated embodiment has a
turn table 15 which is disposed substantially flush with the top
surface of the housing 4 on the front side of the above static
support plate 6. This turn table 15 is formed like a disk having a
relatively large diameter and suitably rotated in a direction
indicated by an arrow 15a by a rotary drive unit that is not shown.
In the illustrated embodiment, three chuck tables 5 are arranged
each other at a phase angle of 120.degree. rotatably on the
horizontal plane on the turn table 15. The chuck tables 5 are
suitable for holding the semiconductor wafer assembly 2 shown in
FIGS. 1 to 3 and will be descried in detail with reference to FIG.
8 and FIG. 9. The chuck table 5 shown in FIG. 8 and FIG. 9 consists
of a disk-like base 51 and a disk-like suction-holding chuck 52.
The base 51 is made from a metal material such as stainless steel,
and a rotary shaft portion 511 projects from the center portion of
the under surface thereof and is rotatably supported onto the turn
table 15 by a bearing that is not shown. Since the rotary shaft
portion 511 is connected to a rotary drive unit that is not shown,
the chuck table 5 is caused to rotate in a direction indicated by
an arrow in FIG. 7 when the rotary drive unit is activated.
[0036] A circular depressed portion 512 whose top portion is open
is formed in the top surface of the base 51 and is connected to a
communication path 513 provided in the rotary shaft portion 511.
The communication path 513 is connected to a suction source that is
not shown. The above suction-holding chuck 52 is formed of a porous
ceramic disk and is fitted in the depressed portion 512 formed in
the above base 51. Thus, the top surface of the suction-holding
chuck 52 fitted in the depressed portion 512 of the base 51 serves
as a semiconductor wafer placing surface 521 for supporting the
back surface of the tape 22 to which the semiconductor wafer 23 of
the above semiconductor wafer assembly 2 has been stuck, as will be
described hereinafter. On the outer peripheral side of depressed
portion 512 in the top surface of the base 51, an annular frame
placing surface 514 for supporting the back surface of the frame 21
of the semiconductor wafer assembly 2 is formed at a position below
the semiconductor wafer placing surface (top surface) of the
suction-holding chuck 52 with a level difference 515 therebetween.
The level difference 515 of this annular frame placing surface 514
is equivalent to the thickness of the frame 21. The suction ports
517 of a plurality of communication paths 516 connected to the
depressed portion 512 are formed in the annular frame placing
surface 514.
[0037] On the chuck table 5 constituted as described above is
placed the semiconductor wafer assembly 2 as shown in FIG. 9. That
is, the back surface of the tape 22 to which the semiconductor
wafer 23 is stuck is placed on the semiconductor wafer placing
surface 521 which is the top surface of the suction-holding chuck
52, and the back surface of the frame 21 is placed on the annular
frame placing surface 514. By connecting the communication path 513
to the suction source (not shown), the semiconductor wafer assembly
2 can be suction-held on the suction-holding chuck 5. Therefore,
the frame 21 is located at a position lower than the semiconductor
wafer 23 by the above level difference 515. Consequently, while the
semiconductor wafer 23 is ground, the grinding wheels 102 and 122
do not interfere with the frame 21. The three chuck tables 5
arranged on the turn table 15 constituted as described above are
moved to a workpiece carrying-in/carrying-out area A,
rough-grinding area B, finish-grinding area C and workpiece
carrying-in/carrying-out A in this order by properly turning the
turn table 15.
[0038] The illustrated grinding machine comprises a first cassette
41, arranged on one side relative to the workpiece
carrying-in/carrying-out area A, for storing the semiconductor
wafer assembly 2 which is a workpiece before grinding, a second
cassette 42, arranged on the other side relative to the workpiece
carrying-in/carrying-out area A, for storing the semiconductor
wafer assembly 2 after grinding, a workpiece placing unit 43
provided between the first cassette 41 and the workpiece
carrying-in/carrying-out area A, a cleaning means 44 provided
between the workpiece carrying-in/carrying-out area A and the
second cassette 42, a workpiece delivering means 45 for delivering
the semiconductor wafer assembly 2 stored in the first cassette 41
to the workpiece placing unit 43 and delivering the semiconductor
wafer assembly 2 cleaned by the cleaning means 44 to the second
cassette 42, a workpiece carrying-in means 46 for carrying the
semiconductor wafer assembly 2 placed on the workpiece placing unit
43 to the top of the chuck table 4 positioned in the workpiece
carrying-in/carrying-out area A, and a workpiece carrying-out means
47 for carrying the semiconductor wafer assembly 2 after grinding
placed on the chuck table 5 positioned in the workpiece
carrying-in/carrying-out area A to the cleaning means 44.
[0039] The semiconductor wafer assembly and the grinding machine in
the illustrated embodiment are constituted as described above, and
their functions will be described hereinafter.
[0040] The semiconductor wafer assembly 2 before grinding stored in
the first cassette 41 is carried by the up and down movement and
forward and reverse movement of the workpiece delivering means 45,
mounted on the workpiece placing unit 43 and centered by the radial
movement toward the center of six pins 431. The semiconductor wafer
assembly 2 which has been mounted on the workpiece placing unit 43
and has centered is placed on the chuck table 5 positioned in the
workpiece carrying-in/carrying-out area A by the turning movement
of the workpiece carrying-in means 46. When the communication path
513 formed in the base 51 of the chuck table 5 is connected to the
suction source (not shown), the back surface of the tape 22 to
which the semiconductor wafer 23 is stuck, of the semiconductor
wafer assembly 2 mounted on the chuck table 5, is sucked to the
semiconductor wafer placing surface 521 of the suction-holding
chuck 52 and the back surface of the frame 21 is suction-held on
the annular frame placing surface 514. When the semiconductor wafer
assembly 2 is suction-held on the chuck table 5, the turn table 15
is turned at 120.degree. in a direction indicated by the arrow 15a
by the rotary drive unit (not shown) to position the chuck table 5
on which the semiconductor wafer assembly 2 has been placed in the
rough-grinding area B.
[0041] When the chuck table 5 on which the semiconductor wafer has
been placed is positioned in the rough-grinding area B, it is
turned in a direction indicated by an arrow by the rotary drive
unit (not shown), and the grinding wheel 102 of the rough-grinding
unit 10 is, while being rotated in a direction indicated by an
arrow, lowered a predetermined amount by the feeding unit 11 so
that the semiconductor wafer 23 of the semiconductor wafer assembly
2 on the chuck table 5 is roughly ground. At this point, since the
frame 21 of the semiconductor wafer assembly 2 held on the chuck
table 5 is located at a position lower than the semiconductor wafer
23 by the above level difference 515 as described above, the frame
21 does not interfere with the grinding wheel 102 at the time when
the semiconductor wafer 23 is ground by the grinding wheel 102.
Further, since the semiconductor wafer placing surface 521 and the
annular frame placing surface 514 of the chuck table 5 are covered
with the frame 21 and the tape 22, contaminants generated by
grinding do not contaminate the placing surfaces, thereby making it
possible to maintain the function of the chuck table with high
accuracy. While this grinding work is thus carried out, the
semiconductor wafer assembly 2 before grinding is mounted on the
next chuck table 5 positioned in the workpiece
carrying-in/carrying-out area A, as described above. The chuck
table 5 on which the roughly ground semiconductor wafer assembly 2
has been placed is then positioned in the finish-grinding area C by
turning the turn table 15 at 120.degree. in a direction indicated
by the arrow 15a. At this point, the next chuck table 5 on which
the semiconductor wafer assembly 2 has been placed in the workpiece
carrying-in/carrying-out area A is positioned in the rough-grinding
area B, and the chuck table 5 after the next is positioned in the
workpiece carrying-in/carrying-out area A.
[0042] The semiconductor wafer 23 of the semiconductor wafer
assembly 2 before rough-grinding placed on the chuck table 5
positioned in the rough-grinding area B is thus roughly ground by
the rough-grinding unit 10 and the semiconductor wafer 23 of the
semiconductor wafer assembly 2 placed on the chuck table 5
positioned in the finish-grinding area C and roughly ground is
finish-ground by the finish-grinding unit 12. During this
finish-grinding, too, the frame 21 of the semiconductor wafer
assembly 2 held on the chuck table 2 is located at a position lower
than the semiconductor wafer 23 by the level difference 515.
Therefore, while the semiconductor wafer 23 is ground by the
grinding wheel 122, the frame 21 does not interfere with the
grinding wheel 122. The chuck table 5 on which the finish-ground
semiconductor wafer assembly 2 has been placed is then positioned
in the workpiece carrying-in/carrying-out area A by turning the
turn table 15 at 120.degree. in a direction indicated by the arrow
15a. The chuck table 5 on which the semiconductor wafer assembly 2
roughly ground in the rough-grinding area B is placed is moved to
the finish-grinding area C and the chuck table 5 on which the
semiconductor wafer assembly 2 before grinding in the workpiece
carrying-in/carrying-ou- t area A is placed is moved to the
rough-grinding area B, respectively.
[0043] The chuck table 5 that has returned to the workpiece
carrying-in/carrying-out area A via the rough-grinding area B and
the finish-grinding area C releases here the suction-holding of the
finish ground semiconductor wafer assembly 2. That is,
communication between the communication path 513 formed in the base
51 of the chuck table 5 and the suction source (not shown) is cut
off. The finish-ground semiconductor wafer assembly 2 on the chuck
table 5 positioned in the workpiece carrying-in/carrying-out area A
is carried to the cleaning means 44 by the workpiece carrying-out
means 47. The semiconductor wafer assembly 2 carried to the
cleaning means 44 is cleaned and then stored at a predetermined
position of the second cassette 42 by the workpiece delivering
means 45.
[0044] A chuck table 5a suitable for holding the semiconductor
wafer assembly 3 shown in FIGS. 4 to 6 will be described with
reference to FIG. 10.
[0045] The chuck table 5a shown in FIG. 10 consists of a disk-like
base 51a and a disk-like suction-holding chuck 52a, like the chuck
table 5 shown in FIGS. 8 and 9. The base 51a is made from a metal
material such as stainless steel, and a rotary shaft portion 511a
projects from the center portion of the under surface thereof and
is rotatably supported to the above turn table 15 of the grinding
machine shown in FIG. 7 by a bearing that is not shown.
[0046] A circular depressed portion 512a whose top portion is open
is formed in the top surface of the base 51a and is connected to a
communication path 513a provided in the rotary shaft portion 511a
and connected to the suction source that is not shown. The
suction-holding chuck 52a is formed of a porous ceramic disk and is
fitted in the depressed portion 512a formed in the above base 51a.
Thus, the top surface of the suction-holding chuck 52a fitted in
the depressed portion 512a of the base 51a serves as a
semiconductor wafer placing surface 521a for supporting the back
surface of the tape 32 to which the semiconductor wafer 33 of the
above semiconductor wafer assembly 3 is stuck, as will be described
hereinafter. In the outer peripheral side of the depressed portion
512a in the top surface of the base 51a, an annular frame placing
surface 514a for supporting the back surface of the frame portion
311 constituting the frame 31 of the semiconductor wafer assembly 3
is formed at a position below the semiconductor wafer placing
surface (top surface) of the suction-holding chuck 52a with a level
difference 515a therebetween. The level difference 515a of this
annular frame placing surface 514a is equivalent to the total of
the thickness of the frame portion 311 and the thickness of the
mounting portion 312 constituting the frame 31. The suction ports
517a of a plurality of communication paths 516a connected to the
above communication path 513a are formed in the annular frame
placing surface 514a.
[0047] On the chuck table 5a constituted as described above is
placed the semiconductor wafer assembly 3 as shown in FIG. 10. That
is, the back surface of the tape 32 to which the semiconductor
wafer 33 is stuck is placed on the semiconductor wafer placing
surface 521a which is the top surface of the suction-holding chuck
52a, and the back surface of the frame portion 311 constituting the
above frame 31 is placed on the annular frame placing surface 514a.
By connecting the communication path 513a to the suction source
(not shown), the semiconductor wafer assembly 3 can be suction-held
on the suction-holding chuck 5a. Therefore, the frame 31 is located
at a position lower than the semiconductor wafer 33 by the level
difference 515a. Consequently, while the semiconductor wafer 23 is
ground, the grinding wheels 102 and 122 of the grinding machine
shown in FIG. 7 do not interfere with the frame 31. Since the
semiconductor wafer placing surface 521a and the annular frame
placing surface 514a of the chuck table 5a are covered with the
frame 31 and the tape 32, contaminants generated by grinding do not
contaminate the mounting surfaces, thereby making it possible to
maintain the function of the chuck table with high accuracy.
[0048] Since the semiconductor wafer assembly and the machining
apparatus according to the present invention are constituted as
described above, the following function and effect are
obtained.
[0049] That is, according to the present invention, since the back
surface of the tape of the semiconductor wafer assembly is stuck to
the surface of the frame and the semiconductor wafer is stuck to
the surface of the above tape, the semiconductor wafer and the
frame are located on opposite sides of the tape, whereby while the
semiconductor wafer is ground, the machining tools do not interfere
with the frame, thereby making it possible to machine the
semiconductor wafer smoothly. Further, as the machined
semiconductor wafer is united with the frame via the tape, it is
not bent by the rigidity of the frame and can be delivered smoothly
and stored in the cassette, even if it has been made thin or
divided.
[0050] According to the present invention, the semiconductor wafer
assembly consists of an annular frame, a tape mounted to the frame,
a semiconductor wafer stuck to the surface of the tape and a fixing
ring for fixing the periphery portion of the tape to the frame, the
tape is placed to the surface of the mounting portion constituting
the annular frame, the fixing ring is fitted onto the outer
circumferential portion of the mounting portion to sandwich the
outer peripheral portion of the tape between the outer peripheral
surface of the mounting portion and the inner peripheral surface of
the fixing ring. Therefore, the tape can be mounted to the frame
without forming an adhesion layer on the back surface of the
tape.
[0051] The machining apparatus according to the present invention
is constituted such that the chuck table for holding the
semiconductor wafer assembly has a semiconductor wafer placing
surface for supporting the back surface of the tape to which the
semiconductor wafer is stuck and an annular frame placing surface
for supporting the back surface of the frame, which is formed, in
the outer peripheral side of the semiconductor wafer placing
surface, at a position below the semiconductor wafer placing
surface with a level difference therebetween. Therefore, the frame
is located at a position where the machining tool does not
interfere with the frame during the machining of the semiconductor
wafer, thereby making it possible to machine the semiconductor
wafer smoothly. Further, as the semiconductor wafer placing surface
and the annular frame placing surface of the chuck table are
covered with the frame and the tape, contaminants generated by
grinding do not contaminate the placing surfaces, thereby making it
possible to maintain the function of the chuck table with high
accuracy.
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