Abrading – Machine – Combined
Reexamination Certificate
2002-07-02
2004-12-07
Peterson, Kenneth E. (Department: 3724)
Abrading
Machine
Combined
C451S069000, C451S289000, C083S861000, C438S464000
Reexamination Certificate
active
06827636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a semiconductor device production method and a semiconductor device production apparatus, and more particularly, to a semiconductor device production method and a semiconductor device production apparatus in which grinding is performed on a wafer stuck to a tape.
In producing a semiconductor device, grinding is performed on the surface of the wafer so as to reduce the thickness of the wafer. However, a large load is applied to the wafer in the grinding step. For this reason, it has been desired that the grinding be performed at a high throughput without damaging the wafer.
2. Description of the Related Art
FIGS. 1
to
6
show a conventional semiconductor device production method and a conventional semiconductor production apparatus. It is widely known that a conventional semiconductor device production method includes a grinding step of grinding the rear surface of the wafer so as to thin the wafer to a desired thickness, and a dicing step of dicing the wafer into individual semiconductor chips.
Conventionally, there are two ways of performing the dicing step and the grinding step: as shown in
FIG. 1A
, the dicing step (step
10
) is followed by the grinding step (step
11
); or, as shown in
FIG. 1B
, the grinding step (step
20
) is followed by the dicing step (step
21
).
FIGS. 2 and 3
illustrate the dicing step (step
10
) and the grinding step (step
11
) of FIG.
1
A.
A wafer
10
to be diced is fixed to a wafer frame
12
provided with a dicing tape
13
. The dicing tape
13
is a resin tape coated with a ultraviolet curing adhesive, and the wafer
10
stuck to the dicing tape
13
is diced. The circuit forming surface (to which the dicing tape
13
is stuck) of the wafer
10
is covered with a protection tape
14
which protects the circuits in the wafer
10
at the time of dicing.
The wafer
10
is diced by a dicing saw
15
, and is divided into individual semiconductor chips
11
. At this point, groove-like gaps
16
each having a width corresponding to the blade width of the dicing saw
15
are formed between the semiconductor chips
11
. The wafer
10
(i.e., the individual semiconductor chips
11
) remains attached to the dicing tape
13
via the protection tape
14
.
FIG. 3
illustrates the grinding step (step
11
) carried out after the dicing step (step
10
). In the grinding-step, a grinder
17
grinds the rear surface of the wafer
10
to thin the wafer
10
to a desired thickness. More specifically, the rotating grinder
17
supplied with an abrasive liquid is moved in the directions of arrows X
1
and X
2
shown in FIG.
3
. Thus, the semiconductor chips
11
having the predetermined thickness can be formed.
FIG. 5
illustrates the grinding step (step
20
) shown in FIG.
1
B. In
FIG. 5
, the same components as in
FIGS. 2 and 3
are indicated by the same reference numerals as well.
In the production method shown in
FIG. 1B
, the grinder
17
grinds the wafer
10
without the gaps
16
, because the grinding step (step
20
) is carried out prior to the dicing step (step
21
). After the wafer
10
is thinned to the predetermined thickness by the grinding, the dicing step is carried out by the dicing saw
15
to form the semiconductor chips
11
.
In the production method shown in
FIG. 1A
, the wafer
10
with the gaps
16
is ground, because the dicing step is carried out prior to the grinding step. The width W1 of each of the gaps
16
is substantially equal to the blade width of the dicing saw
15
. More specifically, the width W1 is as small as about 20 &mgr;m, for instance.
The wafer
10
is diced into the individual semiconductor chips
11
, and the bottom of each of the semiconductor chips
11
is stuck to the dicing tape
13
via the protection tape
14
. Because of this, the fixing force for each of the semiconductor chips
11
is small, often resulting in displacement. Also, since the grinder
17
moves in the directions of the arrows X
1
and X
2
while rotating, a large external force is applied to each of the semiconductor chips
11
.
For the above reasons, the semiconductor chips
11
are displaced at the time of grinding, and collisions occur between the semiconductor chips
11
.
FIG. 4
shows the problem caused when the grinder
17
is moving in the direction of the arrow X
1
. The semiconductor chip
11
on the right side in the figure is subjected to the force (external force) in the X
1
direction along with the movement of the grinder
17
.
The semiconductor chip
11
subjected to the external force is displaced in the direction of an arrow A in the figure, and the upper corner of the semiconductor chip
11
collides with the adjacent semiconductor chip
11
. The displaced position of the semiconductor chip
11
on the right side is indicated by a broken line. Because of the collision, a crack
18
might occur in the upper corner of the semiconductor chip
11
, resulting in a poor production yield and a low throughput.
On the other hand, in the production method shown in
FIG. 1B
, the grinder
17
grinds the wafer
10
without the gaps
16
(as shown in FIG.
5
), because the grinding step is carried out prior to the dicing step. Thus, the crack
18
shown in
FIG. 4
can be prevented.
By the method of
FIG. 1B
, however, a warp is caused in the wafer
10
as shown in
FIG. 10
, when the wafer
10
is ground to the predetermined thickness. Such a warp can be measured by the maximum distance (indicated by an arrow H in the figure) between the dicing tape
13
(or the protection tape
14
) and the wafer
10
. If a 6-inch wafer is ground to a thickness of 200 &mgr;m, a warp of about 2 cm is caused (H=2 cm). If an 8-inch wafer is ground to a thickness of 200 &mgr;m, a warp of about 3 cm is caused (H=3 cm).
With such a warp in the wafer
10
, it is difficult to handle the wafer
10
without damaging it. The possibility of the 8-inch wafer being broken is about 50%, resulting in a poor production yield and a lower throughput.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a semiconductor device production method and a semiconductor device production apparatus in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide a semiconductor device production method and a semiconductor device production apparatus having a large yield and a high throughput.
The above objects of the present invention are achieved by a semiconductor device production method which includes the steps of: sticking a wafer to a tape stretchable by a physical process; dicing the wafer into individual semiconductor chips; stretching the tape by carrying out the physical process after the dicing; and grinding the rear surface of the wafer stuck to the tape after the tape stretching.
The above objects of the present invention are also achieved by another semiconductor device production method which includes the steps of: dicing a wafer whose rear surface is stuck to a dicing tape, the rear surface is opposite to the circuit forming surface of the wafer; sticking a tape onto the circuit forming surface of the wafer after the dicing, and removing the dicing tape from the rear surface of the wafer; stretching the tape by performing the physical process on the tape; and grinding the rear surface of the wafer stuck to the tape after the step of tape stretching.
The above objects of the present invention are also achieved by a semiconductor device production apparatus including: a dicing unit which dices a wafer stuck to a tape stretchable by a physical process; a physical process unit which stretches the tape by performing the physical process on the tape by physical process means; and a grinding unit which grinds a rear surface of the wafer by a grinder, with the tape being stuck to the wafer.
In the semiconductor device production method and apparatus of the present invention, the tape is stretched so that the gaps between the semiconductor chips become wider. With the wider gaps, ev
Armstrong Kratz Quintos Hanson & Brooks, LLP
Flores-Sánchez Omar
Fujitsu Limited
Peterson Kenneth E.
LandOfFree
Semiconductor device production method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor device production method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor device production method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3312174