U.S. patent application number 12/398087 was filed with the patent office on 2009-10-01 for grinding method for grinding back-surface of semiconductor wafer and grinding apparatus for grinding back-surface of semiconductor wafer used in same.
Invention is credited to Shigeharu Arisa, Toshiyuki Ozawa.
Application Number | 20090247050 12/398087 |
Document ID | / |
Family ID | 41011365 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090247050 |
Kind Code |
A1 |
Arisa; Shigeharu ; et
al. |
October 1, 2009 |
GRINDING METHOD FOR GRINDING BACK-SURFACE OF SEMICONDUCTOR WAFER
AND GRINDING APPARATUS FOR GRINDING BACK-SURFACE OF SEMICONDUCTOR
WAFER USED IN SAME
Abstract
A grinding method for grinding a back surface of a semiconductor
wafer that performs infeed grinding of a back surface of a wafer
laminated body, the method, during the grinding of the back surface
of the wafer laminated body, having: measuring respectively a
thickness of an outer peripheral portion and an inner peripheral
portion of the wafer laminated body; calculating a thickness
difference between the thickness of the outer portion and the
thickness the inner portion; and tilting an axis of a grinding
wheel by a predetermined angle in an arbitrary direction so as to
reduce the calculated thickness difference.
Inventors: |
Arisa; Shigeharu; (Tokyo,
JP) ; Ozawa; Toshiyuki; (Tokyo, JP) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
41011365 |
Appl. No.: |
12/398087 |
Filed: |
March 4, 2009 |
Current U.S.
Class: |
451/5 ;
451/10 |
Current CPC
Class: |
B24B 7/228 20130101;
B24B 49/00 20130101 |
Class at
Publication: |
451/5 ;
451/10 |
International
Class: |
B24B 49/04 20060101
B24B049/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
JP |
2008-092932 |
Claims
1. A grinding method for grinding a back surface of a semiconductor
wafer, wherein a wafer laminated body having a support base
material adhered to a front surface of said semiconductor wafer for
protecting a circuit pattern formed on said front surface is fixed
to a table with a front surface faced downward and with a back
surface to be ground faced upward, and wherein, while said wafer
laminated body is being rotated in a horizontal plane and a
grinding wheel is being rotated about a axis of said grinding
wheel, said grinding wheel is moved in a vertical direction at a
predetermined feed speed to thereby grind said back surface of said
wafer laminated body; said method, during grinding of said back
surface of said wafer laminated body, comprising: measuring
respectively a thickness of an outer peripheral portion and an
inner peripheral portion of said wafer laminated body; calculating
a thickness difference between said thickness of said outer portion
and said thickness of said inner portion; and, tilting said axis of
said grinding wheel so as to reduce the calculated thickness
difference.
2. A grinding method for grinding a back surface of a semiconductor
wafer according to claim 1, wherein said axis of said grinding
wheel is tilted such that in-plane pressure distribution in the
contact plane of said grinding wheel and said wafer laminated body
becomes uniform.
3. A grinding method for grinding a back surface of a semiconductor
wafer according to claim 1, wherein, when said thickness of said
outer peripheral portion of said wafer laminated body is less than
said thickness of said inner peripheral portion of said wafer
laminated body, said axis of said grinding wheel is tilted such
that said in-plane pressure in said outer peripheral portion of
said wafer laminated body is comparable to or less than said
in-plane pressure in said inner peripheral portion of said wafer
laminated body.
4. A grinding apparatus for grinding a back surface of a
semiconductor wafer, comprising: a spindle head for supporting a
grinding wheel having a grinding surface disposed in opposition to
said back surface of a wafer laminated body rotatably about an axis
of said grinding wheel; a measurement means for measuring
respectively a thickness of an outer peripheral portion and a
thickness of an inner peripheral portion of said wafer laminated
body; an angle fine adjustment means for tilting said axis of said
grinding wheel relative to a vertical direction; and, a controller
that receives input signal from said measurement means, calculates
a thickness difference between said thickness of said outer
peripheral portion and said thickness of said inner peripheral
portion, and controls said angle fine adjustment means so as to
reduce said thickness difference.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for grinding a
back surface of a semiconductor wafer and to an apparatus for
grinding a back surface of a semiconductor wafer used in the same
method.
[0003] 2. Description of Related Art
[0004] In general, a processing method for reducing thickness of a
semiconductor wafer has been known in which a support base material
formed of glass, resin, etc., is adhered to the front surface of
the semiconductor wafer, and with the semiconductor wafer fixed via
the base material to a vacuum chuck on a turn-table, the back
surface of the wafer is ground. In this method, for example, a
distance from the upper surface of the turn-table to the back
surface of the wafer laminated body is measured by using a contact
type sensor as an in-process gauge, and grinding and in-process
measurement is performed simultaneously without removing the wafer
laminated body from the turn-table until the thickness of the wafer
reaches to a predetermined dimension.
[0005] As an example of related art related to the grinding method
for grinding a back surface of a semiconductor wafer according to
the present invention, a method is disclosed in Japanese Unexamined
Patent Publication No. 2005-205543. Japanese Unexamined Patent
Publication No. 2005-205543, in paragraph [0005], includes a
description that ". . . in order to grind a wafer, there are
several grinding methods for grinding a wafer, and among them, two
main methods are a creep feed grinding method in which a wafer is
ground by being passed between two cylinder grinding wheels forming
a pair, and an infeed grinding method in which a cup shaped
grinding wheel is used such that the cup shaped grinding wheel and
a wafer are both rotated so as to pass the grinding wheel across
the center of the wafer. In particular, the infeed type grinding
method is often used in grinding of a semiconductor wafer since
higher surface flatness can be more easily obtained than with the
creep feed type grinding method."
[0006] Further, in paragraph [0006], there is a description that
"Such an infeed type grinding can be performed, for example, by
using a grinding device 21 as shown in FIG. 8. This grinding device
21 has a chuck table 23 for holding a wafer by vacuum suction, and
a cup type grinding wheel 26 having a grinding head 25 with a
grinding wheel 24 fixed thereto, and one surface of a semiconductor
wafer can be ground, for example, by sucking the semiconductor
wafer 22 to be ground to the chuck table 23 and rotating the wafer,
and, while the grinding head 25 is being rotated about the rotation
axis 27, pressing the grinding wheel 24 to the wafer 22."
[0007] As a problem related to the problem of the present
invention, in paragraph [0005] of Japanese Unexamined Patent
Publication No. 2005-205543, there is a description that "on the
surface of the ground wafer, grinding striations having a certain
periodicity may be formed as the locus of the grinding wheel, or a
concave portion having recessed shape may be formed in the center
portion of the wafer". Although the grinding striations on the
wafer surface can be removed by subsequent polishing process as a
post-processing, there is another problem that the flatness of the
wafer may be deteriorated when the amount of polished wafer is
increased in the polishing process, and productivity may be
lowered.
[0008] The problem that a concave portion may be formed in the
center portion of the wafer, is considered to arise from
complicated interactions of various factors such as the grinding
device, the grinding wheel, the support structure for the wafer
laminated body, conditions for grinding, the grinding method and
the like. The case where a convex portion is formed in the center
portion of the wafer is considered to arise in the same manner. The
back surface of a wafer formed by relative movement of the grinding
wheel and the wafer is thus a result of complicated interaction of
various factors, and therefore, it is considered difficult to
finish the back surface of a wafer so as to achieve the flatness in
a predetermined precision.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a
grinding method for grinding a back surface of a semiconductor
wafer that can suppress formation of a concave portion or a convex
portion in the center portion of the wafer, and that can finish the
back surface of the wafer to a desired flatness, and a grinding
apparatus for grinding a back surface of a semiconductor wafer that
is used in same method.
[0010] In order to attain above object, in accordance with the
present invention, there is provided a grinding method for grinding
a back surface of a semiconductor wafer wherein a wafer laminated
body having a support base material adhered to a front surface
thereof for protecting a circuit pattern is fixed to a table with
the front surface facing downward and a back surface to be ground
facing upward, and in this state, while the wafer laminated body is
being rotated in a horizontal plane and a grinding wheel is being
rotated about its axis, the grinding wheel is moved in a vertical
direction at a predetermined feed speed to thereby grind the back
surface of the wafer laminated body, the method comprising
measuring a thickness of an outer peripheral portion and an inner
peripheral portion of the wafer laminated body while grinding the
back surface of the wafer laminated body, calculating a thickness
difference between the thickness of the outer peripheral portion
and the inner peripheral portion, and tilting the axis of the
grinding wheel so as to reduce the calculated thickness
difference.
[0011] In the grinding method for grinding a back surface of a
semiconductor wafer, it is also possible to tilt the axis of the
grinding wheel so as to achieve a uniform in-plane pressure
distribution in a contact plane between the grinding wheel and the
wafer laminated body.
[0012] In the grinding method for grinding a back surface of a
semiconductor wafer, when the thickness of the outer peripheral
portion of the wafer laminated body is less than the thickness of
the inner peripheral portion of the wafer laminated body, it is
also possible to tilt the axis of the grinding wheel so as to
achieve the in-plane pressure in the outer peripheral portion of
the wafer laminated body that is comparable to or less than the
in-plane pressure in the inner peripheral portion of the wafer
laminated body.
[0013] With the grinding method for grinding a back surface of a
semiconductor wafer as described above, by tilting the axis of the
grinding wheel based on the thickness of the outer peripheral
portion and the inner peripheral portion of the wafer laminated
body measured in-process while infeed grinding of the back surface
of the wafer laminated body is being performed, it is possible to
reduce the thickness difference of the thickness between the outer
peripheral portion and the inner peripheral portion of the wafer
laminated body. Therefore, it is possible to suppress formation of
a concave portion or a convex portion in the center portion of the
wafer and to finish the wafer to a desired flatness.
[0014] In accordance with another aspect of the present invention,
there is provided a grinding apparatus for grinding a back surface
of a semiconductor wafer used in the grinding method for grinding a
back surface of a semiconductor wafer as described above,
comprising a spindle head that supports a grinding wheel having a
grinding surface disposed in opposition to a back surface of the
wafer laminated body rotatably about the axis, measurement means
that measures a thickness of an outer peripheral portion and an
inner peripheral portion of the wafer laminated body, angle fine
adjustment means for tilting the axis of the grinding wheel
relative to a vertical direction, and a controller that receives an
input signal from the measurement means, and calculates a thickness
difference of the thickness between the outer peripheral portion
and the inner peripheral portion to thereby control the angle fine
adjustment means so as to reduce the thickness difference.
[0015] With the grinding apparatus for grinding a back surface of a
semiconductor wafer as described above, by tilting the axis of the
grinding wheel based on the thickness of the outer peripheral
portion and the inner peripheral portion of the wafer laminated
body measured in-process, it is possible to reduce the thickness
difference of the thickness between the outer peripheral portion
and the inner peripheral portion of the wafer laminated body.
Therefore, it is possible to suppress formation of a concave
portion or a convex portion in the center portion of the wafer and
to finish the wafer to a desired flatness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other objects, features and advantages of the
present invention will become more apparent from the following
description of preferred embodiment with reference to appended
drawings, in which:
[0017] FIG. 1 is a perspective view of a grinding apparatus for
grinding a back surface of a semiconductor wafer according to an
embodiment of the present invention;
[0018] FIG. 2 is a view for explaining the infeed grinding;
[0019] FIG. 3 is a view for explaining the state of simultaneous
measurement of the outer peripheral portion and the inner
peripheral portion of the wafer laminated body by using in-process
gauges;
[0020] FIG. 4 is a side view of the grinding apparatus for grinding
a back surface of a semiconductor wafer;
[0021] FIG. 5A is a view for explaining the state of the axis of
the grinding wheel tilted anticlockwise;
[0022] FIG. 5B is a view for explaining the state of the axis of
the grinding wheel tilted clockwise; and
[0023] FIG. 6 is a flow chart of the grinding method for grinding a
back surface of a semiconductor wafer.
DETAILED DESCRIPTION
[0024] A grinding method for grinding a back surface of a
semiconductor wafer according to the present invention and a
grinding apparatus for grinding a back surface of a semiconductor
wafer used in same according to a preferred embodiment of the
invention will be described with reference to drawings. FIG. 1 is a
view of a representative form of a grinding apparatus for grinding
a back surface of a semiconductor wafer according to the present
invention, although the present invention is not limited to this
embodiment. Grinding apparatus 1 for grinding a back surface of a
semiconductor wafer according to this embodiment has apparatus main
body la, turn-table 2 for holding wafer laminated body 10 by vacuum
suction with chuck 3 of the front surface side of wafer laminated
body 10 having support base material 13 adhered thereto, spindle
head 4 for rotatably supporting grinding wheel 15. Spindle head 4
as an exemplary form may have a linear movement feed mechanism for
moving grinding wheel 15 up and down in a vertical direction, and a
rotary mechanism for rotating grinding wheel 15 about vertical axis
R2. In this example, a ball screw feed mechanism can be applied as
the linear movement feed mechanism, and a servo motor can be
applied as the rotary mechanism.
[0025] As shown in FIG. 3, individual wafer laminated body 10 held
by individual chuck 3 by vacuum suction is detachably held by chuck
3 in the state in which glass base material (support base material)
13 is adhered via a protective film (not shown) to front surface
12a having a circuit pattern formed thereon, although the present
invention is not limited to this embodiment. As an example, the
thickness of semiconductor wafer 11 before grinding is about 750
.mu.m, the thickness of a protective film is about 100 .mu.m, and
the thickness of a glass base material is about 1 mm. Semiconductor
wafer 11 is ground to a predetermined thickness, for example to a
thickness as thin as about 30 .mu.m, based on s grinding allowance
calculated from the thickness of a single wafer.
[0026] Grinding apparatus 1 for grinding a back surface is adapted
to be used to perform infeed grinding. As shown in FIG. 2, infeed
grinding is performed while both grinding wheel 15 and wafer
laminated body 10 are being simultaneously rotated. Thus, grinding
wheel 15 mounted to spindle head 4 is disposed in a predetermined
positional relation in a horizontal plane (X-Y plane) in opposition
to wafer laminated body 10, and wafer laminated body 10 together
with chuck 3 is rotated about axis R1, while grinding wheel 15 is
being rotated about axis R2 in the same direction as wafer
laminated body 10, and in this state, grinding wheel 15 is moved
downward in a vertical direction so as to press back surface 12b of
wafer 11 with force F by grinding surface 16a to thereby perform
grinding of back surface 12b of wafer 11. In FIG. 2, the directions
of rotation of grinding wheel 15 and of wafer laminated body 10 are
the same, although the direction of rotation of grinding wheel 15
and of wafer laminated body 10 may be different from each other.
When the directions of rotation of grinding wheel 15 and of wafer
laminated body 10 are the same, grinding resistance is lowered and
precision of processing of wafer 11 can be improved, and when the
directions of rotation of grinding wheel 15 and of wafer laminated
body 10 are different, grinding efficiency can be increased.
[0027] Grinding apparatus 1 for grinding a back surface according
to this embodiment has several unique features. Grinding apparatus
1 for grinding a back surface according to this embodiment further
has in-process gauges 5, 6 (see FIG. 3) for simultaneously
measuring the thickness of the outer peripheral portion and the
inner peripheral portion of wafer laminated body 10 while grinding
wafer back surface 12b, angle fine adjustment means 12 for tilting
axis R2 of grinding wheel 15 relative to the vertical direction,
controller 16 that receives input signal from in-process gauges 5,
6 and calculates the thickness difference between the thickness of
the outer peripheral portion and the inner peripheral portion, and,
based on the calculated thickness difference, controls the servo
motor of angle fine adjustment means 12 so as to reduce the
calculated thickness difference. The controller has an operation
section and an automatic angle adjustment section. In the operation
section, it receives the input signal from the contact type sensor
and calculates the thickness difference between the thickness of
the outer peripheral portion and the inner peripheral portion. In
the automatic angle adjustment section, it controls the servo motor
of angle fine adjustment means 12 based on a predetermined relation
between the calculated thickness difference and the angle of axis
R2 of grinding wheel 15.
[0028] Each of the components of grinding apparatus 1 for grinding
a back surface according to the present embodiment will be
described below.
[0029] Each in-process gauge 5, 6 as a representative form of
measurement means is a measuring instrument in which the change of
probe 5a, 5b as a contactor is converted to a voltage signal by a
differential transformer, and based on the converted voltage
signal, the distance between the upper surface of turn-table 2 and
back surface 12b of the wafer, that is, thickness .delta. of wafer
laminated body 10, is monitored in-process (see FIG. 3). Thickness
.delta. varies for individual wafer laminated body 10, but since
grinding is performed to a position obtained by subtracting the
grinding allowance from thickness .delta., individual semiconductor
wafer 11 can be ground always to the same thickness without being
affected by the tolerance of support base material 13 or the
protective film.
[0030] The grinding apparatus for grinding a back surface according
to the present invention has three in-process gauges 5, 6, 7.
In-process gauge 7 is used for measuring the position of the upper
surface of turn-table 2, and two in-process gauges 5, 6 are used
for measuring the thickness of the outer peripheral portion and the
inner peripheral portion of wafer laminated body 10, respectively.
By providing two in-process gauges 5, 6, the thickness of the outer
peripheral portion and the inner peripheral portion of wafer
laminated body 10 can be measured simultaneously in-process, so
that non-uniform distribution of grinding pressure in the contact
plane of grinding wheel 15 and wafer laminated body 10 can be
estimated. The number of the in-process gauges for measuring the
thickness of wafer laminated body 10 is not limited to two in the
present invention, and three or more in-process gauges may be
provided for this purpose.
[0031] Turn-table 2 is formed in the shape of a disc, and is
provided with four rotatable chucks 3. Individual chuck 3 is
adapted to suck with a vacuum pressure glass base material 13
adhered to wafer laminated body 10. Wafer laminated body 10 is
thereby held on chuck 3. After grinding of the back surface is
completed, air is supplied to chuck 3 so that wafer laminated body
10 can be quickly removed from chuck 3. On the underside of
individual chuck 3, output shaft 21 of motor 20 is attached
coaxially with the center axis of chuck 3. Individual chuck 3 is
adapted to be rotated clockwise by the driving force of motor
20.
[0032] Grinding wheel 15 is used for grinding back surface 12b of
semiconductor wafer 10 held in suction on turn-table 2, and a
diamond grinding wheel with liquid bond as binder, for example, can
be used. By using a liquid bond as a binder, grinding wheel 15 has
resilience, and the force of impact at the time of contact of the
grinding wheel with wafer laminated body 10 is relaxed, and highly
precise processing of back surface 12b of the wafer can be
achieved.
[0033] Grinding wheel 15 is attached to spindle head 4 with axis R2
aligned coaxially with the output shaft of the motor (not shown),
and is rotated anticlockwise by the driving force of the motor.
Truing of grinding wheel 15 is performed on the apparatus, and
grinding surface 16a opposed to back surface 12b of the wafer is
shaped flat. Dressing is performed to regenerate new sharp edges on
the surface of grinding wheel 15 with lowered sharpness.
[0034] Spindle head 4 has spindle 9 having grinding wheel 15
mounted thereto, a ball screw feed mechanism as a linear movement
feed mechanism that moves grinding wheel 15 up and down in a
vertical direction, a servo motor that rotates grinding wheel 15
about axis R2, and angle fine adjustment means 12 that tilts axis
R2 of grinding wheel 15 relative to a vertical direction. By moving
grinding wheel 15 in the direction approaching to semiconductor
wafer 11, grinding wheel 15 is abutted to back surface 12b of
semiconductor wafer 11, and a predetermined surface pressure F can
be applied to grind back surface 12b of wafer (see FIG. 2).
[0035] FIG. 5A and FIG. 5B are views of axis R2 of the grinding
wheel 15 being tilted in-process relative to the vertical direction
by angle fine adjustment means 12. As shown in FIG. 5A, when the
thickness of the outer peripheral portion of wafer laminated body
10 is less than the thickness of the inner peripheral portion, that
is, when a concave portion (not shown) is formed in the center
portion of semiconductor single wafer 11 (when the outer peripheral
portion of single semiconductor wafer is formed with thickness
larger than thickness of the inner peripheral portion), axis R2 of
grinding wheel 15 and spindle 9 is tilted anticlockwise by angle
.theta.1 depending on the thickness difference, such that the
grinding pressure (in-plane pressure) on the outer peripheral
portion of wafer laminated body 10 is comparable to or less than
the grinding pressure on the inner peripheral portion of wafer
laminated body 10. With such construction, the thickness difference
between the outer peripheral portion and the inner peripheral
portion of wafer laminated body 10 becomes equal to zero or nearly
equal to zero, and the grinding pressure in the contact plane of
grinding wheel 15 and wafer laminated body 10 is leveled, and back
surface 12b of the wafer can be formed flat.
[0036] On the contrary, as shown in FIG. 5B, when the thickness of
the outer peripheral portion of wafer laminated body 10 is greater
than the thickness of the inner peripheral portion, that is, when a
convex portion is formed in the center portion of single
semiconductor wafer 11 (when the outer peripheral portion of single
semiconductor wafer is formed with thickness smaller than thickness
of the inner peripheral portion), axis R2 of grinding wheel 15 and
spindle 9 is tilted clockwise by angle .theta.2 depending on the
thickness difference, such that the grinding pressure (in-plane
pressure) on the outer peripheral portion of wafer laminated body
10 is comparable to or greater than the grinding pressure on the
inner peripheral portion of wafer laminated body 10. With such
construction, the thickness difference between the outer peripheral
portion and the inner peripheral portion of wafer laminated body 10
becomes equal to zero or nearly equal to zero, and the grinding
pressure in the contact plane of grinding wheel 15 and wafer
laminated body 10 is leveled, and back surface 12b of the wafer can
be formed flat.
[0037] Next, referring to FIG. 6, the grinding method for grinding
a back surface of a semiconductor wafer by using grinding apparatus
1 for grinding a back surface will be described. First, at step S1,
wafer laminated body 10 is caused to be sucked to chuck 3 with the
front surface of wafer laminated body 10 faced downward and the
back surface of wafer laminated body 10 faced upward. At step S2,
thickness .delta. of wafer laminated body 10 integral with glass
base material 13 is measured by using an in-process gauge or an IR
sensor on the apparatus, and the grinding allowance is obtained by
subtracting the final thickness of wafer 11 from thickness .delta.
of wafer laminated body 10. The grinding allowance is inputted to
the controller in order to control grinding apparatus 1 for
grinding a back surface with respect to grinding allowance.
[0038] Then, at step S3, the turn-table 2 is rotated, and the wafer
laminated body 10 is positioned so as to bring the wafer laminated
body 10 and the grinding wheel 15 in opposition to each other.
Next, at step S4, the wafer laminated body 10 is rotated by the
motor 20, and while the grinding wheel 15 attached to the spindle
head 4 is being rotated by a motor, the ball screw is driven to
move the grinding wheel 15 downward and to bring the grinding
surface 16a into pressing contact with the back surface of the
semiconductor wafer 11 to grind the back surface 12b of the
wafer.
[0039] At step S5, while the back surface of the wafer is being
ground, the thickness of the outer peripheral portion and the inner
peripheral portion of wafer laminated body 10 is measured by using
in-process gauges 5, 6 in region where wafer laminated body 10 does
not come into contact with grinding wheel 15. After the thickness
difference between the thickness of the outer peripheral portion
and the inner peripheral portion of wafer laminated body 10 is
calculated at step S6 in the operation section of unshown
controller, axis R2 of grinding wheel 15 and spindle 9 is tilted by
a predetermined angle in an arbitrary direction so as to reduce the
calculated thickness difference at step S7.
[0040] Finally, at step S8, with axis R2 of grinding wheel 15 and
spindle 9 tilted as described above, back surface 12b of the wafer
is processed by a predetermined grinding allowance, and the
processing of the back surface is completed.
[0041] After grinding has been completed, with wafer laminated body
10 fixed to chuck 3, polishing is performed by using an unshown
polishing device in order to remove the layer damaged by the
grinding. Damages such as unintended cracks of wafer 11 can be
thereby prevented. After polishing has been completed, wafer
laminated body 10 is removed from chuck 3 and transferred to next
processing step, and coating or dicing step is performed.
[0042] Thus, with the grinding method for grinding a back surface
of a semiconductor wafer and the grinding apparatus for grinding a
back surface of a semiconductor wafer used in same, while wafer
laminated body 10 is being ground, axis R2 of grinding wheel 15 and
spindle 9 can be tilted by a predetermined angle in an arbitrary
direction based on the thickness of the outer peripheral portion
and the inner peripheral portion of wafer laminated body 10
measured in-process so as to level the grinding pressure in the
contact plane of grinding wheel 15 with wafer laminated body 10,
and back surface 12b of the wafer can be formed flat.
[0043] The present invention is not limited to the embodiment as
described above, but may be implemented in various modifications
without departing from the scope and spirit of the invention. In
the present embodiment, wafer laminated body 10 is composed of
semiconductor wafer 11, a protective film and glass base material
13, although the wafer laminated body may be composed of a
semiconductor wafer, a protective film and a resin base material,
as another embodiment. Liquid adhesive may be used in place of a
protective film for adhering semiconductor wafer 11 and base
material 13 to each other.
[0044] Grinding apparatus 1 of the present embodiment has
in-process gauges 5, 6, although other measurement means may be
used as long as a thickness of wafer laminated body 10 fixed to
turn-table 2 can be measured.
* * * * *