Information
-
Patent Grant
-
6422227
-
Patent Number
6,422,227
-
Date Filed
Friday, November 3, 200023 years ago
-
Date Issued
Tuesday, July 23, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Eley; Timothy V.
- Nguyen; Dung Van
Agents
- Nixon Peabody LLP
- Safran; David S.
-
CPC
-
US Classifications
Field of Search
US
- 125 1301
- 125 14
- 125 20
- 451 1
- 451 2
- 451 8
- 083 73
- 083 425
-
International Classifications
-
Abstract
In a dicing apparatus that comprises a first blade and a second blade, the first blade cuts a wafer along a street along which the first blade has not previously cut the wafer, and the second blade cuts the wafer along a street along which the first blade has not cut the wafer, and then kerfs made by the blades are inspected. In this method, the kerfs are made along the different streets, and thus the kerfs made by the blades can be accurately inspected.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a dicing apparatus, a kerf inspecting method and a kerf inspecting system, and more particularly to a dicing apparatus that has two spindles to which blades are attached, a kerf inspecting method and a kerf inspecting system.
2. Description of Related Art
A dicing apparatus cuts a wafer with an outer diameter blade with abrasive grains into the dice. The blade becomes worn, and thus chipping occurs and the center of the blade is displaced from the center of a street (a border line between chips on the wafer) along which the wafer is cut due to heat deformation of the blade. Therefore, the dicing apparatus inspects a groove (a kerf) made by the blade at a predetermined time. The dicing apparatus determines a position and a width of the kerf and whether chipping has occurred by imaging the kerf with a camera and processes the image, or an operator determines them manually by sight.
The dicing apparatus has one spindle to which the blade is attached or two spindles. A twin-spindle dicing saw with two spindles cuts the wafer along two streets at one time or in the step-cut method. In the step-cut method, a first blade cuts the wafer along a street to make a groove with a predetermined depth, and then a second blade cuts the wafer along the groove to cut off the wafer along the street.
Conventionally, the twin-spindle dicing saw inspects kerfs made by the blades as follows. First, the first blade cuts the wafer along a street to make a kerf with the predetermined depth, and the dicing saw inspects the kerf made by the first blade. Then, the second blade cuts the wafer along the kerf made by the first blade to make a kerf, and the dicing saw inspects the kerf made by the second blade.
As described above, the dicing saw cuts the wafer to make the kerfs in the same way as in the cutting operation and inspects the kerfs.
In the conventional kerf inspecting method, however, the groove g made by the second blade is along the same street as the groove G made by the first blade as shown in FIG.
8
(
a
), and thus it is difficult to inspect the kerfs by processing the images. In particular, if the blades are of the same thickness as shown in FIG.
8
(
b
), the groove G
1
made by the first blade can not be distinguished from the groove G
2
made by the second blade, and thus the kerfs can not be accurately inspected.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a dicing apparatus that can accurately inspect kerfs, a kerf inspecting method and a kerf inspecting system.
To achieve the above-mentioned object, the present invention is directed to a dicing apparatus, comprising: a first blade which cuts a wafer along a street on the wafer to make a groove with a predetermined depth; and a second blade which cuts the wafer along the groove to cut off the wafer along the street, wherein the dicing apparatus sets a time and a position at which each blade makes a kerf for inspecting the kerf.
According to the present invention, the dicing apparatus sets the time and the position at which each blade makes the kerf for inspecting the kerf. Thus, each blade can make the kerf at the most suitable time at the most suitable position.
To achieve the above-mentioned object, the present invention is directed to a kerf inspecting method for a dicing apparatus that comprises a first blade cutting a wafer along a street on the wafer to make a groove with a first predetermined depth and a second blade cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of: cutting, in a state where the wafer has not been cut along a street, the wafer along the street with the second blade to make a kerf with a second predetermined depth; and inspecting the kerf made by the second blade;
According to the present invention, the second blade cuts the wafer along the street along which the first blade has not cut the wafer to make the kerf with the predetermined depth, and then the dicing apparatus inspects the kerf made by the second blade. Therefore, since the kerf is made along the street along which the first blade has not cut the wafer, the kerf made by the second blade is accurately inspected.
Preferably, the second predetermined depth of the kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the kerf is inspected, the first blade cuts the wafer along the kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the street. Thereby, the kerf made by the second blade can be erased by the first blade, and the cutting operation can be resumed without any trouble after the kerf is inspected.
To achieve the above-mentioned object, the present invention is directed to a kerf inspecting method for a dicing apparatus that comprises a first blade cutting a wafer along a street on the wafer to make a groove with a first predetermined depth and a second blade cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of: cutting, in a state where the wafer has not been cut along a first street, the wafer along the first street with the first blade to make a first kerf with a second predetermined depth; cutting, in a state where the wafer has not been cut along a second street, the wafer along the second street with the second blade to make a second kerf with a third predetermined depth; and inspecting the first and second kerfs made by the first blade and the second blade.
According to the present invention, the kerfs are made by the blades along different streets to be inspected. Therefore, the kerfs made by the blades can be accurately inspected.
Preferably, the third predetermined depth of the second kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the second kerf is inspected, the first blade cuts the wafer along the second kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the second street. Thereby, the kerf made by the second blade can be erased by the first blade, and the cutting operation can be resumed without any trouble after the kerf is inspected.
Preferably, the second predetermined depth of the first kerf made by the first blade is equal to the first predetermined depth of the groove made by the first blade. However, the second predetermined depth of the first kerf made by the first blade can be different from the first predetermined depth of the groove made by the first blade.
BRIEF DESCRIPTION OF THE DRAWINGS
The nature of this invention, as well as other objects and advantages thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein:
FIG. 1
is a plan view showing a structure of a twin-spindle dicing saw;
FIG. 2
is a front view showing the structure of the twin-spindle dicing saw;
FIGS.
3
(
a
),
3
(
b
) and
3
(
c
) are explanation drawings showing the step-cut method;
FIG. 4
is a flow chart showing a method in which kerfs are automatically inspected at a predetermined time;
FIGS.
5
(
a
),
5
(
b
),
5
(
c
),
5
(
d
) and
5
(
e
) are explanation drawings showing a kerf inspecting method;
FIG. 6
is a flow chart showing a method in which kerfs are inspected in accordance with an instruction of an operator;
FIG. 7
is a flow chart showing a case in which the operator inspects the kerf manually by sight; and
FIGS.
8
(
a
) and
8
(
b
) are explanation drawings showing conventional kerf inspecting methods.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
This invention will be described in further detail by way of example with reference to the accompanying drawings.
FIG. 1
is a plan view showing a structure of a twin-spindle dicing saw
10
to which the present invention is applied.
As shown in
FIG. 1
, the twin-spindle dicing saw
10
comprises a wafer table
12
that holds a wafer W, a pair of cutting units
14
A and
14
B that cuts the wafer W held on the wafer table
12
, a pair of imaging units
16
A and
16
B that images the wafer W, and a controlling device (not shown).
The wafer table
12
is shaped like a disc, and it holds the bottom of the wafer W by suction. The wafer table
12
is moved along the X-axis in
FIG. 1
by a moving mechanism (not shown). The wafer table
12
is also rotated about its axis (θ-axis) by a rotating mechanism (not shown).
The wafer W is held on the wafer table
12
while being mounted on a wafer frame (not shown). The wafer W is held on the wafer table
12
while being put on a wafer sheet stuck on the wafer frame.
The cutting units
14
A and
14
B have blades
20
A and
20
B, respectively, that cut the wafer W, and the blades
20
A and
20
B are connected to spindles
22
a
and
22
b
of spindle motors
22
A and
22
B, respectively. The cutting units
14
A and
14
B are separately moved along the Y-axis in FIG.
1
and the Z-axis by a spindle moving mechanism.
As shown in
FIG. 2
, the spindle moving mechanism has Y a pair of carriages
24
A and
24
B. The Y carriages
24
A and
24
B are slidably provided on guide rails
26
provided along the Y-axis. The Y carriages
24
A and
24
B are separately slid along the Y-axis by sliding devices (not shown) such as liner motors.
The Y carriages
24
A and
24
B have Z moving mechanisms
28
A and
28
B, respectively, composed of linear guides and driving devices (not shown). The Z moving mechanisms
28
A and
28
B moves Z carriages
30
A and
30
B along the Z-axis in FIG.
2
. Motor brackets
32
A and
32
B are attached to the ends of the Z carriages
30
A and
30
B, and the spindle motors
22
A and
22
B are attached to the motor brackets
32
A and
32
B.
The above-described spindle moving mechanism moves the cutting units
14
A and
14
B along the Y-axis and the Z-axis. The sliding of the Y carriages
24
A and
24
B along the guide rails
26
moves the cutting units
14
A and
14
B along the Y-axis, and the moving of the Z carriages
30
A and
30
B of the Z moving mechanisms
28
A and
28
B moves the cutting units
14
A and
14
B along the Z-axis (upward and downward). The moving of the cutting units
14
A and
14
B along the Y-axis changes cutting pitches, and the moving of the cutting units
14
A and
14
B along the Z-axis changes depths of cut.
As shown in
FIG. 1
, the imaging units
16
A and
16
B have ITV cameras
34
A and
34
B, respectively. The ITV cameras
34
A and
34
B are held by camera holders
36
A and
36
B, which are fixed to the motor brackets
32
A and
32
B. The ITV cameras
34
A and
34
B image the top of the wafer W held on the wafer table
12
, and outputs the image data to an image processing device
38
. The image processing device
38
inspects grooves (kerfs) made by the blades
20
A and
20
B by processing the image data. In the kerf inspection, the image processing device
38
determines kerf positions, kerf widths and whether or not chipping has occurred.
The controlling device controls the wafer table
12
and the cutting units
14
A and
14
B in accordance with a predetermined cutting pattern to cut the wafer W held on the wafer table
12
along streets on the wafer W. The controlling device inspects the kerfs at a predetermined time or in accordance with an instruction of an operator.
The wafer cutting method for the above-described twin-spindle dicing saw
10
will now be explained.
The twin-spindle dicing saw
10
cuts the wafer W in the step-cut method. First, the first blade
20
A cuts the wafer W along the streets with a predetermined depth, and then the second blade
20
B cuts the wafer W along the grooves made by the first blade
20
A to cut off the wafer W along the streets.
The first blade
20
A that cuts the wafer W first is thicker than the second blade
20
B.
The detail of the cutting method is as follows.
First, the controlling device drives the spindle motors
22
A and
22
B to rotate the first blade
20
A and the second blade
20
B. Then, the controlling device drives the sliding devices of the spindle moving mechanism to move the first blade
20
A and the second blade
20
B so that the interval between the blades
20
A and
20
B is a predetermined interval. In this embodiment, the predetermined interval is the same as three pitches between the streets.
Then, the controlling device drives the Z moving mechanisms
28
A and
28
B to lower the blades
20
A and
20
B predetermined distances. This sets the depths of cut for the blades
20
A and
20
B to predetermined depths of cut.
The predetermined depth of cut for the second blade
20
B is larger than that for the first blade
20
A so that the second blade
20
B cuts off the wafer W along the streets by cutting the wafer W along the grooves G made by the first blade
20
A.
After setting the depths of cut, the controlling device drives the spindle motors
22
A and
22
B to rotate the first blade
20
A and the second blade
20
B. Then, the controlling device drives the moving mechanism to move the wafer table
12
along the X-axis. This cuts the wafer W along a street S
X1
with the predetermined depth to make a groove G
X1
with the predetermined depth along the street S
X1
(see FIG.
3
(
a
)).
Next, the controlling device drives the sliding devices of the spindle moving mechanism to move the first blade
20
A and the second blade
20
B one pitch along the Y-axis. Then, the controlling device moves the wafer table
12
along the X-axis again so that the first blade
20
A cuts the wafer W along the next street S
X2
.
The above-described cutting operation is repeated again and again so that the first blade
20
A sequentially cuts the wafer W along the streets S
X1
, S
X2
, . . . along the X-axis.
As shown in FIG.
3
(
b
), when the first blade
20
A reaches the fourth street S
X4
, the second blade
20
B is in the first groove G
X1
. The controlling device drives the moving mechanism to move the wafer table
12
along the X-axis so that the first blade
20
A cuts the wafer W along the fourth street S
X4
with the predetermined depth and the second blade
20
B cuts the wafer W along the first groove G
X1
to cut off the wafer W along the first street S
X1
.
After that, the controlling device drives the sliding devices of the spindle moving mechanism to move the first blade
20
A and the second blade
20
B one pitch along the Y-axis. Then, the controlling device moves the wafer table
12
along the X-axis so that the first blade
20
A cuts the wafer W along the fifth street S
X5
and the second blade
20
B cuts the wafer W along the second groove G
X2
as shown in FIG.
3
(
c
). The above-described cutting operation is repeated again and again so that the first blade
20
A and the second blade
20
B sequentially cut off the wafer W along the streets S
X1
, S
X2
, . . . along the X-axis.
After the wafer W is cut off along all the streets S
X1
, S
X2
, . . . along the X-axis, the controlling device rotates the wafer table
12
by 90°, and then the first blade
20
A and the second blade
20
B sequentially cut off the wafer W along streets S
Y1
, S
Y2
, . . . along the Y-axis in the same way as the streets S
X1
, S
X2
, . . . . The wafer W is finally cut into the dice.
The kerf inspecting method applied to the above-described twin-spindle dicing saw
10
will now be explained.
The controlling device inspects the kerfs at the predetermined time or in accordance with the instruction of the operator.
The method in which the controlling device automatically inspects the kerfs at the predetermined time will be first explained.
FIG. 4
is a flow chart showing the method in which the controlling device automatically inspects the kerfs at the predetermined time.
If a mode for automatically inspecting the kerfs is selected, the controlling device counts the number of streets along which the first blade
20
A has cut the wafer W and the number of streets along which the second blade
20
B has cut the wafer W When one of the numbers reaches a predetermined number, the controlling device automatically starts inspecting the kerfs (step
1
).
First, the controlling device determines which blade has cut the wafer W along the predetermined number of streets (step
2
). The case in which both blades
20
A and
20
B have cut the wafer W along the predetermined numbers of streets will now be explained.
As shown in FIG.
5
(
a
), the first blade
20
A cuts the wafer W along the fifth street S
X5
to make the groove G
5
with the predetermined depth and the second blade
20
B cuts the wafer W along the second groove G
2
made by the first blade
20
A. The controlling device suspends the cutting operation when both blades
20
A and
20
B have cut the wafer W along the predetermined numbers of streets.
Then, as shown in FIG.
5
(
b
), the controlling device moves the second blade
20
B to the street S
6
along which the first blade
20
A has not cut the wafer W (step
3
). Next, the second blade
20
B cuts the wafer W along the street S
6
with a predetermined depth (step
4
).
After that, the ITV camera
34
A images the groove G
5
made by the first blade
20
A as shown in FIG.
5
(
c
). Then, the image processing device
38
processes the image data to inspect the kerf made by the first blade
20
A (step
5
). In the kerf inspection, the image processing device
38
determines the position and the width of the groove G
5
made by the first blade
20
A and whether or not chipping has occurred in the groove G
5
.
Next, the ITV camera
34
B images the groove g
6
made by the second blade
20
B as shown in FIG.
5
(
d
). Then, the image processing device
38
processes the image data to inspect the kerf made by the second blade
20
B (step
6
). In the kerf inspection, the image processing device
38
determines the position and the width of the groove g
6
made by the second blade
20
B and whether or not chipping has occurred in the groove g
6
.
After the kerf inspections, the controlling device determines whether or not the kerfs are normal according to the results of the kerf inspection (step
7
). If the kerfs are abnormal, the controlling device issues a warning and stops the operation of the dicing saw (step
8
). If the kerfs are normal, the controlling device restarts cutting the wafer W (step
9
). As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
Since the groove g
6
has been made along the street S
6
by the second blade
20
B in the kerf inspection, the first blade
20
A cuts the wafer W along the groove g
6
to make the groove G
6
with the predetermined depth.
In the kerf inspecting method, the second blade
20
B cuts the wafer W along the street S
6
before the first blade
20
A, and thus the kerfs can be accurately inspected.
The depth of the groove g
6
made by the second blade
20
B in the kerf inspection is smaller than that of the groove G
6
made by the first blade
20
A along the same street S
6
after the kerf inspections.
The case in which only the first blade
20
A has cut the wafer W along the predetermined number of streets will now be explained. In this case, only a kerf made by the first blade
20
A is inspected.
Since the first blade
20
A cuts the wafer W along the street S
5
before the second blade
20
B as shown in FIG.
5
(
a
), the first blade
20
A never cuts the wafer W along a groove made by the second blade
20
B. Thus, a kerf can be inspected soon after the kerf is made by the first blade
20
A in the regular cutting.
The controlling device suspends the cutting operation when the first blade
20
A has cut the wafer W along the predetermined number of streets. After that, the ITV camera
34
A images the groove G
5
made by the first blade
20
A as shown in FIG.
5
(
c
). Then, the image processing device
38
processes the image data to inspect the kerf made by the first blade
20
A (step
10
).
After the kerf inspection, the controlling device determines whether or not the kerf is normal according to the results of the kerf inspection (step
7
). If the kerf is abnormal, the controlling device issues a warning and stops the operation of the dicing saw (step
8
). If the kerf is normal, the controlling device restarts cutting the wafer W (step
9
). As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
The case in which only the second blade
20
B has cut the wafer W along the predetermined number of streets will now be explained. In this case, only a kerf made by the second blade
20
B is inspected.
Since the second blade
20
B cuts the wafer W along the street S
2
after the first blade
20
A as shown in FIG.
5
(
a
), the kerf can not be accurately inspected in this state.
When the second blade
20
B has cut the wafer W along the predetermined number of streets, the controlling device moves the second blade
20
B to the street S
6
along which the first blade
20
A has not cut the wafer W (step
11
). Next, the second blade
20
B cuts the wafer W along the street S
6
with the predetermined depth as shown in FIG.
5
(
b
) (step
12
). After that, the ITV camera
34
B images the groove g
6
made by the second blade
20
B as shown in FIG.
5
(
d
). Then, the image processing device
38
processes the image data to inspect the kerf made by the second blade
20
B (step
13
).
After the kerf inspection, the controlling device determines whether or not the kerf is normal according to the results of the kerf inspection (step
7
). If the kerf is abnormal, the controlling device issues a warning and stops the operation of the dicing saw (step
8
). If the kerf is normal, the controlling device restarts cutting the wafer W (step
9
). As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
Since the groove g
6
has been made along the street S
6
by the second blade
20
B in the kerf inspection, the first blade
20
A cuts the wafer W along the groove g
6
to make the groove G
6
with the predetermined depth.
In the kerf inspecting method, the second blade
20
B cuts the wafer W along the street S
6
before the first blade
20
A, and thus the kerf can be accurately inspected.
The method in which the controlling device inspects the kerfs in accordance with the instruction of the operator will be explained next.
FIG. 6
is a flow chart showing the method in which the controlling device inspects the kerfs in accordance with the instruction of the operator.
If the operator inputs the instruction for the automatic kerf inspection with an outside inputting device (not shown) (step
20
), the controlling device suspends the cutting operation after cutting the wafer W along the current street whether or not the mode for automatically inspecting the kerfs is selected.
The operator determines whether to inspect a kerf made by the first blade
20
A or inspect a kerf made by the second blade
20
B, and inputs which blade with the inputting device to the controlling device (step
21
). The case in which the operator chooses the first blade
20
A will be first explained.
Since the first blade
20
A cuts the wafer W along the street S
5
before the second blade
20
B as shown in FIG.
5
(
a
), the first blade
20
A never cuts the wafer W along a groove made by the second blade
20
B. For this reason, the controlling device inspects the latest kerf in this case.
Then, the ITV camera
34
A images the groove G
5
made by the first blade
20
A. Next, the image processing device
38
processes the image data in order to inspect the kerf made by the first blade
20
A (step
22
). After the kerf inspection (step
23
), the controlling device or the operator determines whether or not the kerf is normal according to the results of the kerf inspection. If the kerf is abnormal, the controlling device issues a warning and stops the operation of the dicing saw. If the kerf is normal, the controlling device restarts the cutting of the wafer W As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
The case in which the operator chooses the second blade
20
B will be explained next.
Since the second blade
20
B cuts the wafer W along the street S
2
after the first blade
20
A as shown in FIG.
5
(
a
), the kerf can not be accurately inspected in this state.
Then, the controlling device moves the second blade
20
B to the street S
6
along which the first blade
20
A has not cut the wafer W (step
24
). Next, the second blade
20
B cuts the wafer W along the street S
6
with the predetermined depth as shown in FIG.
5
(
b
) (step
25
).
After that, the ITV camera
34
B images the groove g
6
made by the second blade
20
B as shown in FIG.
5
(
d
). Then, the image processing device
38
processes the image data to inspect the kerf made by the second blade
20
B (step
26
).
After the kerf inspection (step
23
), the controlling device or the operator determines whether or not the kerf is normal according to the results of the kerf inspection. If the kerf is abnormal, the controlling device issues a warning and stops the operation of the dicing saw. If the kerf is normal, the controlling device restarts the cutting of the wafer W. As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
In the kerf inspecting method, the second blade
20
B cuts the wafer W along the street S
6
before the first blade
20
A, and thus the kerf can be accurately inspected.
The case in which the operator inspects the kerfs manually by sight instead of the image processing device
38
will now be explained.
FIG. 7
is a flow chart showing the case in which the operator inspects the kerf manually by sight.
If the operator inputs the instruction for the kerf eye-inspection with the outside inputting device (not shown) (step
30
), the controlling device suspends the cutting operation after cutting the wafer W along an operator-designated street whether or not the mode for automatically inspecting the kerfs is selected (step
31
).
Then, the controlling device moves the second blade
20
B to the street S
6
along which the first blade
20
A has not cut the wafer W (step
32
). Next, the second blade
20
B cuts the wafer W along the street S
6
with the predetermined depth as shown in FIG.
5
(
b
) (step
33
). After that, the controlling device stops the operation of the twin-spindle dicing saw
10
(step
34
).
The operator inspects the kerfs manually by sight with a monitor or a microscope. In the inspections, the operator determines the positions and the widths of the grooves made by the first blade
20
A and the second blade
20
B and whether or not chipping has occurred in the grooves. After the kerf inspections, the operator determines whether or not the kerfs are normal according to the results of the kerf inspections. If the kerfs are abnormal, the operator stops the operation of the dicing saw. If the kerfs are normal, the operator restarts the cutting operation. As shown in FIG.
5
(
e
), the first blade
20
A cuts the wafer W along the street S
6
with the predetermined depth and the second blade
20
B cuts the wafer W along the groove G
3
.
In the kerf inspecting method, the second blade
20
B cuts the wafer W along the street S
6
before the first blade
20
A, and thus the kerfs can be accurately inspected.
The first blade
20
A is thicker than the second blade
20
B in the embodiment, but they may be of the same thickness. In this case, if the kerfs were made along the same street in the conventional kerf inspecting method, the positions and the widths of the kerfs could not be accurately determined. However, in the kerf inspecting method of the present invention, the kerfs are made along different streets, and thus the positions and the widths of the kerfs can be accurately determined.
In the embodiment, the operation of the dicing saw is stopped when a kerf is abnormal. However, if a kerf position is abnormal, the kerf position may be automatically corrected before the operation of the dicing saw is restarted. In this case, a gap δ between the center of the street and the center of the groove is calculated from the result of the kerf inspection (the centers are the same if the groove is precisely made), and the blade position is corrected so that the gap δ becomes 0. After the correction, the cutting operation is restarted. Therefore, the dicing saw can always cut the wafer W precisely without being stopped.
The dicing saw has the pair of imaging units
16
A and
16
B in the embodiment, but they may be integrated as one unit.
As set forth hereinabove, according to the kerf inspecting method of the present invention, the first blade and the second blade cut the wafer along the different streets. Thus, the kerfs can be accurately inspected.
It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the invention is to cover all modifications, alternate constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.
Claims
- 1. A kerf inspecting method for a dicing apparatus that comprises a first blade for cutting a wafer having a plurality of streets along selected streets on the wafer to make a groove with a first predetermined depth and a second blade for cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of:cutting a wafer along a selected street on the wafer to make a groove with a first predetermined depth with the first blade; cutting-off part of the wafer along the groove formed in the selected street by the first blade using the second blade; cutting the wafer along an uncut street with the second blade to make an inspection kerf with a second predetermined depth; and inspecting the inspection kerf made by the second blade.
- 2. The kerf inspecting method as defined in claim 1, wherein:the second predetermined depth of the kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the kerf is inspected, the first blade cuts the wafer along the kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the street.
- 3. A kerf inspecting method for a dicing apparatus that comprises a first blade for cutting a wafer having a plurality of streets along selected streets on the wafer to make a groove with a first predetermined depth and a second blade for cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of:cutting the wafer along uncut first street with the first blade to make a first inspection kerf with a second predetermined depth; cutting the wafer along uncut second street with the second blade to make a second inspection kerf with a third predetermined depth; and inspecting the first and second inspection kerfs made by the first blade and the second blade.
- 4. The kerf inspecting method as defined in claim 3, wherein:the third predetermined depth of the second kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the second kerf is inspected, the first blade cuts the wafer along the second kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the second street.
- 5. The kerf inspecting method as defined in claim 3, wherein the second predetermined depth of the first kerf made by the first blade is equal to the first predetermined depth of the groove made by the first blade.
- 6. A kerf inspecting system for a dicing apparatus that comprises a first blade, a second blade and a controlling device, the controlling device being adapted to control the first blade and the second blade so that the first blade cuts a wafer having a plurality of streets along a selected street on the wafer to make a groove with a first predetermined depth and the second blade cuts the wafer along the groove to cut off the wafer along the street,wherein, when the second blade has cut the wafer along a predetermined number of streets, the controlling device is adapted to make the second blade cut the wafer along uncut street to make an inspection kerf with a second predetermined depth; wherein the dicing apparatus further comprises an imaging device and an image processing device; wherein the controlling device makes the imaging device capture an image of the kerf made by the second blade; and wherein the controlling device makes the image processing device inspect the kerf by processing the image captured by the imaging device.
- 7. A kerf inspecting system for a dicing apparatus that comprises a first blade, a second blade and a controlling device, the controlling device being adapted to control the first blade and the second blade so that the first blade cuts a wafer having a plurality of streets along a selected street on the wafer to make a groove with a first predetermined depth and the second blade cuts the wafer along the groove to cut off the wafer along the street,wherein, when the second blade has cut the wafer along a predetermined number of streets, the controlling device is adapted to make the second blade cut the wafer along uncut street to make an inspection kerf with a second predetermined depth; wherein the second predetermined depth of the kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and wherein, after the kerf is inspected, the first blade cuts the wafer along the kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the street.
- 8. A kerf inspecting system for a dicing apparatus that comprises a first blade, a second blade and a controlling device, the controlling device being adapted to control the first blade and the second blade so that the first blade cuts a wafer having a plurality of streets along a selected street on the wafer to make a groove with a first predetermined depth and the second blade cuts the wafer along the groove to cut off the wafer along the street,wherein the controlling device is adapted to respond to an instruction signal for a kerf inspection of the second blade input from an outside inputting device in a manner causing the second blade to cut the wafer along an uncut street to make an inspection kerf with a second predetermined depth, wherein the dicing apparatus further comprises an imaging device and an image processing device; wherein the controlling device makes the imaging device capture an image of the kerf made by the second blade; and wherein the controlling device makes the image processing device inspect the kerf by processing the image captured by the imaging device.
- 9. A kerf inspecting system for a dicing apparatus that comprises a first blade, a second blade and a controlling device, the controlling device being adapted to control the first blade and the second blade so that the first blade cuts a wafer having a plurality of streets along a selected street on the wafer to make a groove with a first predetermined depth and the second blade cuts the wafer along the groove to cut off the wafer along the street,wherein the controlling device is adapted to respond to an instruction signal for a kerf inspection of the second blade input from an outside inputting device in a manner causing the second blade to cut the wafer along an uncut street to make an inspection kerf with a second predetermined depth; wherein the second predetermined depth of the kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and wherein, after the kerf is inspected, the first blade cuts the wafer along the kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the street.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-316605 |
Nov 1999 |
JP |
|
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6192289 |
Geffen et al. |
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B1 |
6102023 |
Ishiwata et al. |
Aug 2000 |
A |
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Nov 2000 |
A |
6216682 |
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Apr 2001 |
B1 |