JP3505827B2 - Dicing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dicing method for IC chips formed on a silicon wafer, and more particularly to a dicing method for narrow and long chips such as line image sensor chips.

[0002]

2. Description of the Related Art Generally, a cross section of a peripheral portion of a silicon wafer 6 is as shown in FIG. 3 in order to prevent a decrease in IC patterning yield due to adhesion of silicon debris generated from the peripheral portion.

Therefore, during dicing, cutting water or the like enters between the peripheral portion of the silicon wafer 6 and the dicing tape, and the water pressure causes the peripheral silicon pieces to be peeled off from the dicing tape and scattered.

In particular, in the case of a small width and long chip such as a line type image sensor chip, the peripheral silicon piece 5 of the silicon wafer 6 has a comma number of millimeters square, and thus the scattering number increases. The scattered peripheral silicon pieces 5 scratch everywhere on the silicon wafer 6 and generate many defective chips.

This state is briefly shown in FIG. In FIG. 4, 1 is a dicing cut line and 2 is a dicing tape. The dicing blade 3 advances from left to right while rotating at 20,000 to 50,000 rpm in the direction of the arrow in the figure.

Cutting water or the like receives the centrifugal force of the dicing blade 3 and enters the gap between the peripheral silicon piece 5 and the dicing tape 2 with a strong force. At this time, a force in the peeling direction is applied to the peripheral silicon pieces 5, and those having a small contact area with the dicing tape 2 scatter. The scattered peripheral silicon pieces 5 scratch the silicon wafer 6.

FIG. 5 shows an outline of a dicing method conventionally implemented as a solution to this problem. As can be seen by comparing this method with the thickness in FIG. Lapping is performed until it is halved to prevent cutting water from entering during dicing.

However, in this conventional example, in this case, the wafer lapping is costly. Moreover, since the chip thickness becomes thinner, chip cracks are likely to occur in the die mount in the subsequent process, and the die adhesive may crawl up to the chip surface (hereinafter, these are collectively referred to as "conventional examples"). ).

[0009]

SUMMARY OF THE INVENTION Here, the present invention is intended to solve these problems, and is low in cost, does not hinder the post-process, and reliably causes chip damage defects due to scattering of the peripheral portion. An object is to provide a dicing method for preventing.

[0010]

To achieve this object, the present invention provides a dicing blade by supplying cutting water.
Therefore, it is a dicing method for dicing a wafer.
The wafer in the dicing blade penetration direction
Keep it between the upper surface around the tip of the
Dicing method with protective tape to prevent cutting water from entering
Is the law. Further , a dicing method in which the protective tape material is polyolefin is preferable . Still more preferably, it is a dicing method in which the roller is rotated while pressing it against the surface of the protective tape via an elastic body, and the protective tape is attached to the upper surface of the wafer.

[0011]

The present invention has the above-mentioned configuration,
It is possible to reliably prevent silicon fragments from scattering at low cost,
Since there is no need for wafer wrapping, no problems occur at the time of die mounting, resulting in a dramatic improvement in product yield.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view showing an outline of a dicing method in one embodiment of the present invention.

In FIG. 1, 1 is a dicing cut line and 2 is a dicing tape. The dicing blade 3 is 20,000 to 50,000 rp in the direction of the arrow in the figure.
Rotating from m, proceeding from left to right.

Reference numeral 4 is a protective tape made of a polyolefin material as a base material. The peripheral silicon piece 5 is a dicing tape 2.
It is arranged to sandwich between and.

Cutting water or the like receives the centrifugal force of the dicing blade 3 and tries to enter the gap between the peripheral silicon piece 5 and the dicing tape 2 with a strong force, but is completely shut out by the protective tape 4.

As a result, the peripheral silicon pieces 5 are not scattered at all. The base material of the protective tape 4 is not limited to the polyolefin type, and the presence or absence of the adhesive layer does not matter.

FIG. 2 is a side view of a protective tape mounting device used in one embodiment of the present invention.

In FIG. 2, 6 is a silicon wafer. The silicon wafer 6 is held by a dicing tape 2 (not shown) in a metal ring 7 by a commercially available tape mounter (not shown).

The silicon wafer 6 is placed on the stage 8 in this state. At this time, the silicon wafer 6 is positioned by the positioning holes 9a and 9b provided on the ring 7 and the positioning pins 10a and 10b provided on the stage 8.

Here, if positional accuracy is particularly required, it is possible to use a pattern recognition unit (not shown) and attach a drive system in the XY axes and the rotational direction to the stage 8.

Positioned silicon wafer 6
Through the suction holes 11 provided on the stage 8 in large numbers,
It is vacuum-adsorbed and fixed. The protective tape 4 is supplied in a reel form inside the apparatus, and is held by the chucks 12a and 12b. Reference numeral 13 denotes a resin roller for attaching the protective tape 4, which is processed into a size suitable for the target work.

Further, the roller 13 includes the chucks 12a and 1a.
Drive the required stroke between 2b. When the roller 13 is driven, the dicing tape 2 is passed through the protective tape 4
A spring 14 or the like is attached so that a constant load is applied in the pushing direction, and the protective tape 4 is attached to a predetermined position by the adhesive force of the dicing tape 2. 15
Is a cutter, which cuts the protective tape 4 between the roller 13 and the chuck 12a.

The supply of the protective tape 4 and the sticking operation by the roller 13 will be briefly described. The roller 13 is at the origin position A at the beginning. Chuck 12 in this state
b is driven to the position of the chuck 12a, and the protective tape 4
Hold the end of. Next, the chuck 12a is opened, and the chuck 12b pulls out the protective tape 4,
Move to the position shown in FIG.

After the movement is completed, the roller 13 descends to the sticking start position B and the chuck 12a is closed. In this state, the cutter 15 slides to cut the protective tape 4. After cutting, the roller 13 moves from right to left in the figure while attaching the protective tape 4. When the roller 13 reaches about 80% of the predetermined stroke length, the chuck 12b is released. The roller 13 further moves until reaching a predetermined stroke, then returns on the same path and returns to the origin position A. After that, the stage 8 descends and the work is discharged.

Next, a first experimental example of the present invention will be described. Dicing was performed by the method of the above-described first embodiment of the present invention, and the number of scattered silicon pieces around the wafer and the number of scratches generated on the wafer were counted. For the test, a 6-inch silicon wafer (thickness: 680 μm) was used and the length was 8 m.
Dicing was performed at a pitch of m / width of 0.4 mm. Also,
As the protective tape 4, a polyolefin tape having no adhesive layer was used. Protective tape 4 as Comparative Example 1a
A test similar to that of one example was performed except that was not used. As Comparative Example 1b, a silicon wafer 6 lapped to a half thickness (350 μm) was used, and the same test as that of the example was performed without using the protective tape 4. The results of these Examples and Comparative Examples 1a and 1b are shown in (Table 1).

[0027]

[Table 1]

As can be seen from Table 1, the dicing method using the protective tape 4 of the present invention greatly reduces the number of scattered silicon pieces as compared with the conventional example, and as a result, the scratch occurrence rate of the silicon wafer 6 is drastically reduced. To be done. The drop is at the same level as the lapping processed product.

Further, a second experimental example of the present invention will be mentioned. Using the silicon wafer 6 diced in the first experimental example, the electrical defect rate after die mounting was measured. As the comparative examples 2a and 2b, the dicing silicon wafer 6 of the comparative examples 1a and 1b was used, and the same test as the first experimental example was performed. The results are shown in (Table 2).

[0030]

[Table 2]

As can be seen from (Table 2), the dicing method of the present invention significantly reduces electrical defects due to flaws on the silicon wafer 6 as compared with the conventional example (Comparative Example 2a). In addition, a conventional wrapped silicon wafer 6
Compared to (Comparative Example 2b), chip cracks and defects due to creeping up of the die adhesive were also significantly reduced.

[0032]

As is apparent from the above description, the dicing method according to the present invention allows the peripheral portion of the wafer, which easily scatters during the dicing process, to be subjected to a simple process of attaching a protective tape in advance. Partial scattering of silicon fragments can be reliably prevented, and a particular effect of significantly reducing wafer defects can be achieved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an outline of a dicing method according to an embodiment of the present invention.

FIG. 2 is a side view of a protective tape mounting device used in an embodiment of the present invention.

FIG. 3 is a schematic side sectional view of a peripheral portion of a silicon wafer.

FIG. 4 is a schematic diagram briefly explaining the principle of scattering of silicon fragments in the peripheral portion of a silicon wafer.

FIG. 5 is a side sectional view showing an outline of a conventional (lapped) silicon wafer.

[Explanation of symbols]

1 Dicing cut line 2 dicing tape 3 dicing blade 4 protective tape 5 Peripheral silicon 6 Silicon wafer 7 ring 8 stages 9a, 9b Positioning hole 10a, 10b Positioning pin 11 Adsorption hole 12a, 12b chuck 13 roller 14 spring 15 cutter

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/301

Claims (3)

(57) [Claims] 1. A dicing blade by supplying cutting water.
Therefore, dicing method der to perform the dicing of the wafer
Therefore, in the intrusion direction of the dicing blade
The upper surface of the periphery of the wafer tip and the dicing tape
A protective tape is stuck between the surface and the cutting water to prevent it from entering
A dicing method comprising: 2. The dicing method according to claim 1, wherein the protective tape material is polyolefin. 3. Rotate the roller while pressing a roller through the elastic member on the surface of the protective tape, according to claim 1 or 2, characterized in that for sticking the protective tape on the upper surface of the wafer Dicing method.