Dicing method

Details Dicing method Dicing method

2000-09-12

2002-12-24

Chaudhuri, Olik (Department: 2813)

Semiconductor device manufacturing: process

Semiconductor substrate dicing

Having specified scribe region structure

C438S033000, C438S068000, C438S113000, C438S464000

Reexamination Certificate

active

06498075

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a dicing method of cutting a workpiece into the form of a lattice by using a cutting blade having an annular cutting edge.
DESCRIPTION OF THE PRIOR ART
In the production of semiconductor devices, for example, a surface of a nearly disk-like semiconductor wafer is sectioned into plural rectangular regions by cutting lines called first streets and second streets that are arranged in the form of a lattice pattern, and a predetermined circuit pattern is formed on each of these rectangular regions. The plural rectangular regions on each of which the circuit pattern has been formed are cut into individual pieces to obtain so-called semiconductor chips. The cutting of the semiconductor wafer is usually carried out by using a precision cutting apparatus called dicing apparatus. The dicing apparatus is equipped with a cutting blade
54
that is shown in FIG.
5
. The cutting blade
54
comprises a base plate (hub)
541
and an annular cutting edge
542
provided on an outer peripheral portion on one side surface of the base plate
541
. The cutting blade
54
that is generally called hub blade is mounted being sandwiched between a flange portion
572
of a fixing flange
57
and a holding flange
58
by fitting the a plate
541
to a tool-mounting portion
571
of the fixing flange
57
attached on a rotary spindle
56
and then by screwing the holding flange
58
onto an end of the fixing flange
57
. The workpiece is moved correlative to each other to the cutting blade
54
mounted on the rotary spindle
56
in a direction at right angles to the rotary shaft of the cutting blade
54
to execute the cutting.
The dicing method of cutting the semiconductor wafer into the form of a lattice pattern by the cutting blade
54
will now be described with reference to FIG.
7
. In
FIG. 7
, reference numeral
11
denotes a semiconductor wafer which is the workpiece to be treated, and on the surface thereof are formed plural first streets
11
a
in parallel with each other and plural second streets
11
b
formed in parallel with each other in a direction at right angles to the first streets
11
a .
Referring to FIG.
7
(
a
), a semiconductor wafer
11
is so positioned that the first streets
11
a
are in a cut-feeding direction (that is a direction of moving a workpiece for cutting it) indicated by an arrow X and the cutting blade
54
is brought to a side edge of the semiconductor wafer
11
. Here, the cutting blade
54
is set so that the side of the base plate
541
is on the side of an unworked region of the semiconductor wafer
11
which is the workpiece to be treated, i.e., that the side of the cutting edge
542
is located on the upstream side (upper side in
FIG. 7
) in an indexing direction indicated by an arrow Y
1
. Referring to FIG.
7
(
b
), a forward cutting step is effected to cut the plural first streets la by sequentially and repetitively executing a cut-feeding for moving the semiconductor wafer
11
and the cutting blade
54
correlative to each other in a direction which is the cut-feeding direction indicated by an arrow X and an index-feeding for moving the cutting blade
54
in the indexing direction indicated by an arrow Y
1
after one street is cut. After the forward cutting step has been finished, a rotational positioning step is executed to turn the semiconductor wafer
11
by 90 degrees as shown in FIG.
7
(
c
), so that the second streets
1
b
are located in the cut-feeding direction indicated by an arrow X. At this moment, the cutting edge
542
of the cutting blade
54
is on the side of the unworked region of the semiconductor wafer
11
which is the workpiece, namely, the cutting edge
542
of the cutting blade
54
faces the downstream side (upper side in
FIG. 7
) in the indexing direction indicated by an arrow Y
2
. Then, referring to FIG.
7
(
d
), the plural second streets
11
b
are cut by a return cutting step in which the cut-feeding for moving the semiconductor wafer
11
and the cutting blade correlative to each other in a direction which is the cut-feeding direction indicated by an arrow X and the index-feeding for moving the cutting blade
54
in the indexing direction indicated by the arrow Y
2
after one street has been cut are executed sequentially and repetitively. According to the above-mentioned dicing method, a forward and return movement of the cutting blade
54
in the indexing direction (indicated by arrows Y
1
and Y
2
) makes it possible to cut the semiconductor wafer
11
into the form of a lattice along the first streets
11
a
and the second streets
11
b
, whereby a very good productivity can be obtained.
In the above-mentioned dicing method, however, the cutting edge
542
of the cutting blade
54
undergoes great damage and becomes no longer usable before it is worn out. Therefore, the cutting blade must be frequently renewed, resulting in an increase of costs for the tools and for replacement.
SUMMARY OF THE INVENTION
The present inventors have conducted keen study in an effort to investigate the cause of damage to the cutting edge and have discovered the following fact. That is, though the semiconductor wafer is mounted on a frame via a tape, a pellet formed by the cutting in the forward cutting step may peel off the tape and fly when cutting of the wafer is performed by the cutting edge revolving at a speed as high as 20,000 to 30,000 rpm. The pellet
110
that peeled off may hit the outer peripheral edge
541
a
of the base plate
541
of the cutting blade
54
as shown in
FIG. 6
to bite into the cutting edge
542
to damage the cutting edge
542
. When the workpiece to be treated is a semiconductor wafer
11
of a disk-like shape, in particular, small and sharp triangular pellets are formed on the outer periphery by the dicing due to its disk-like shape. The sharp pellets
110
peel off easily because they are adhered at small contact areas on the tape
112
, and bite into between the base plate
541
and the cutting edge
542
to damage the cutting edge
542
.
Further, as a result of study by the present inventors, it was found that even when the pellets fly toward the side where the cutting edge
542
of the base plate
541
is provided and hit the cutting edge
542
, the phenomenon shown in
FIG. 6
does not occur since there is no base plate
541
and hence, the pellets that have flown do not bite into the cutting edge
542
.
It is therefore an object of the present invention to provide a dicing method capable of preventing the cutting edge from being damaged by the flying pellets formed by the cutting.
In order to accomplish the above-mentioned object, according to the first invention, there is provided a dicing method of cutting a workpiece having plural first streets formed in parallel with each other and plural second streets formed in parallel with each other in a direction to intersect said first streets at a predetermined angle, along said first streets and said second streets by using a cutting blade having an annular cutting edge formed along the outer peripheral portion on one side surface of a base plate, wherein said dicing method comprises:
the first cutting step in which the plural first streets are cut by sequentially repeating the cut-feeding for positioning the workpiece so that the first streets are in the cut-feeding direction and for moving said workpiece and said cutting blade correlative to each other in the cut-feeding direction and the index-feeding for moving said workpiece and said cutting blade correlative to each other in an index direction at right angles to the cut-feeding direction to index the gap of said first streets;
a rotational positioning step in which after said first cutting step has been finished, said workpiece is turned by a predetermined angle to be positioned so that said second streets are in the cut-feeding direction, and said cutting blade is positioned at one side edge of said workpiece so that said base plate of said cutting blade faces the side of the unworked region of said workpiece; and
the second cutting step

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