JPH0770503B2 - Semiconductor wafer cutting method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cutting method for dividing a semiconductor wafer into chips.

Conventional Technique A conventional technique will be described with reference to FIGS. 3 and 4.

In FIG. 3, as a cutting method for dividing the semiconductor wafer 1 into chips, there is a method of forming a groove having a constant depth in a scribe lane 3 between the chips 2 with a blade which rotates at a high speed. The cross section of the semiconductor wafer at the center of the cutting groove after cutting, for example, XX 'is as shown in FIG. The thickness t of the uncut portion (diagonal line) is 130 to 200 μm.

Problems to be Solved by the Invention The semiconductor wafer 1 that has been cut in the scribe lane 3 is then cut into uncut portions to form individual chips. As shown in FIG. 5, the uncut portion is often cleaved from the bottom of the cutting groove toward the back surface of the semiconductor wafer 1 at an angle of 45 degrees with respect to the side surface of the cutting groove or the back surface of the semiconductor wafer. . When the cleavage plane 4 appears outside the side surface of the chip, the cross section of the chip 2, for example the AA 'cross section, is the fifth area.
As shown in FIG. 6A, the width of the back surface of the chip is larger than the width of the front surface of the chip by about twice the uncut thickness t of the semiconductor wafer. Therefore, as the uncut thickness of the semiconductor wafer is larger, the width of the chip mounting plate 5 needs a margin larger than the original width of the chip 2 (width of the chip surface), and the chip mounting plate 5 becomes large.

On the other hand, the cleavage plane 4 when dividing the semiconductor wafer is shown in FIG. 5 (b).
When it appears inside the side surface of the chip 2 as shown in (3), the thickness of the chip becomes small at the peripheral portion of the chip, and chipping or cracking of the chip is likely to occur in the subsequent assembly process. This defect becomes more likely to occur as the uncut thickness of the semiconductor wafer increases.

From this, it is preferable that the uncut thickness of the semiconductor wafer is smaller, but if it is too small, the semiconductor wafer after cutting will be easily cracked by a slight force or impact, and it will be conveyed from the semiconductor wafer cutting step to the step of dividing into chips Accidents that a semiconductor wafer breaks during cleaning work.

The present invention provides a method for cutting a semiconductor wafer, which has a small uncut thickness of the semiconductor wafer and can prevent an accident that the semiconductor wafer is broken after cutting.

Means for Solving the Problems In order to solve the above problems, the present invention forms a cutting groove between chips of a semiconductor wafer at a first depth at a peripheral portion of the semiconductor wafer, and has a depth greater than that of the peripheral portion. The inner region is formed with a second depth which is larger than the first depth and smaller than the thickness of the semiconductor wafer.

Effect According to such a cutting method, the semiconductor wafer from which the product chips are obtained has a large uncut thickness at the peripheral edge of the semiconductor wafer, and even the semiconductor wafer after cutting has sufficient strength to withstand conveyance and cleaning operations. Be drunk

EXAMPLE An example of a semiconductor wafer cutting method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view at the center of a cutting groove of a semiconductor wafer according to the present invention. The cutting groove is shallow in the peripheral portion of the semiconductor wafer 11, for example, in the range of 10 to 20 mm from the outer periphery of the semiconductor wafer 11 (for example, the uncut thickness t ₁ is 200 μm).
Above, the cutting groove is formed deeper than that (for example, the uncut thickness t ₂ is 70 to 120 μm). A conventional dicing saw can be used as a device for performing the above cutting, and can be easily prepared by changing a control program of the height of the blade. The semiconductor wafer cut in this way has a small uncut thickness in the region where a chip to be a product is obtained, and even after being divided into chips, the increase or decrease in the width of the chip back surface due to the generation of the cleavage plane can be reduced. Therefore, as shown in FIG.
Even when the cleavage plane (14) appears outside the side surface of the chip, the width of the back surface of the chip does not increase as compared with the width of the front surface of the chip. For this reason, the width of the chip mounting plate 15 does not require a large margin with respect to the original width (width of the surface) of the chip.
Further, as shown in FIG. 2 (b), even when the cleavage surface 14 of the chip 12 appears inside the side surface of the chip, the area where the thickness of the chip becomes small is very small. Almost no chipping or cracking occurs.

On the other hand, since the uncut thickness is large in the peripheral portion of the semiconductor wafer where almost no good product chips are obtained, sufficient strength is maintained even after cutting the semiconductor wafer,
It is possible to prevent accidents where semiconductor wafers are broken during transportation and cleaning work.

As described above, according to the present invention, the cutting groove between the chips of the semiconductor wafer is formed shallow at the peripheral portion of the semiconductor wafer and deep inside, so that the width of the chip back surface is not larger than that of the conventional chip width. Therefore, the chip mounting plate can be downsized. Moreover, cracks and cracks are less likely to occur at the shallow peripheral edge of the chip, and it is possible to prevent the semiconductor wafer from being broken during transportation and cleaning of the cut semiconductor wafer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor wafer according to the present invention at the center of a cutting groove, and FIGS. 2A and 2B are cross-sectional views of chips after dividing the semiconductor wafer according to the present invention into chips. 2A is a cross-sectional view including a chip mounting plate, FIG. 3 is a plan view showing an example of a scribe lane of a semiconductor wafer, and FIG. 4 is a cutting groove center of a semiconductor wafer cut by a conventional technique. Sectional view, FIG. 5 (a)
FIG. 5B is a cross-sectional view of a chip after dividing a semiconductor wafer cut by the conventional technique into chips, and FIG. 5A is a cross-sectional view including a chip mounting plate. 11 …… Semiconductor wafer, 12 …… Chip, 14 …… Cleaved surface

Claims (1)

[Claims] 1. A cutting groove between chips of a semiconductor wafer is formed to have a first depth at a peripheral portion of the semiconductor wafer, and the cutting groove is larger than the first depth in a region inside the peripheral portion. There is formed a semiconductor wafer having a second depth which is smaller than the thickness of the semiconductor wafer.