JPS6336988A - Dividing method for semiconductor wafer - Google Patents

Abstract

PURPOSE:To improve cutting quality by forming grooves to a semiconductor wafer by cutting with a dicing blade, then projecting laser light to the groove bottom, thereby making fusion cutting of the semiconductor wafer. CONSTITUTION:The semiconductor wafer 10 is imposed on the self-adhesive surface of a self-adhesive sheet 12 consisting of a UV curing resin, etc., and is joined by thermocompression bonding. The wafer 10 is then set to a dicing device and the cutting groove 14 is formed along the outside shape of a semiconductor chip 11 except the prescribed margin L to be left uncut by cutting with the dicing blade 13. Further, the wafer 10 is set to a laser device and the part remaining without being cut of the groove 14 is fusion-cut by the projection of the laser light. Since the part remaining without being cut is cut by the laser light, the cracking of the semiconductor chip 11 and the exfoliation thereof from the sheet 12 are prevented. The time for working is shortened as well. The cutting quality of the wafer to is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for dividing a semiconductor wafer into individual semiconductor chips.

<Prior Art> As a means of dividing a semiconductor wafer on which semiconductor elements and integrated circuits are formed into individual semiconductor chips, there is a method called a scribing method. In this scribing method, after a semiconductor wafer is attached to a stretchable adhesive sheet, shallow dividing grooves are formed on the surface of the semiconductor wafer along the outline of the semiconductor chip using a diamond scriber or laser irradiation.
This is a method in which the semiconductor wafer is pressed and bent with a rubber roller or the like, and the semiconductor wafer is split along the dividing grooves.

However, according to this scribing method, since the wafer is folded from the dividing groove based on the crystal orientation, the divided semiconductor chips become rhomboids, which can lead to poor mounting to the lead frame, especially if the semiconductor wafer is thick. Chips occur in semiconductor chips during wire bonding.

Therefore, in order to avoid the above-mentioned inconveniences caused by division using the scribe method, the following division method is adopted. In other words, there are two methods: (1) the barf cut method, in which the semiconductor wafer is cut almost to the center in the thickness direction with a cutting tool, and then the semiconductor wafer is bent and split, or (2) the through-cut method, in which the semiconductor wafer is cut at once with a cutting tool. be.

<Problems to be Solved by the Invention> The final division of the semiconductor wafer in the half-cut method (2) involves bending and dividing the semiconductor wafer, similar to the scribing method. Therefore, the ends of each divided semiconductor chip have acute angles and are easily chipped, and the chipped portions may adhere to the semiconductor chip and cause a short circuit between electrodes.

Further, in the through-cut method (2), there is no need to break the semiconductor wafer, so there is no problem as described above.

However, a horizontal crank may occur just before the dicing blade finishes cutting the semiconductor wafer, or the cut semiconductor chips may be dragged by the dicing blade rotating at high speed and peeled off from the adhesive sheet. this@
If you use a sticky adhesive sheet to prevent separation,
Since the adhesive component of the adhesive sheet adheres to the back surface of the semiconductor chip, mounting failure of the semiconductor chip occurs. Moreover,
In this through-cut method, the cutting margin is required for complete cutting, so the dicing blade reaches inside the adhesive sheet, so the adhesive component of the adhesive sheet adheres to the blade surface of the dicing blade, causing the blade to cut. The surface becomes clogged and the cutting quality deteriorates. On the other hand, sharp cuts are formed in the adhesive sheet by the dicing blade, so when the adhesive sheet is stretched to make it easier to take out the semiconductor chips after dividing the semiconductor wafer, the adhesive sheet is torn. It will no longer be possible to install it on the machine.

To solve this problem, it is conceivable to fuse the entire thickness of the semiconductor wafer with a laser, but in that case, the thicker the semiconductor wafer becomes, the longer the processing time required for fusing increases. Since the heat generated by this is transmitted to the semiconductor chip, the characteristics of the semiconductor chip may deteriorate or thermal cracks may occur. Therefore, such a laser method is not suitable for dividing semiconductor wafers.

In view of these conventional problems, it is an object of the present invention to provide a semiconductor wafer dividing method that can eliminate various disadvantages of the above-mentioned dividing methods by improving the through-cut method (2).

<Means for Solving the Problems> The present invention is characterized in that a groove is formed in a semiconductor wafer by cutting with a dicing blade, and then the semiconductor wafer is fused by irradiating the bottom of the groove with a laser. It is.

<Example> Hereinafter, an example of the semiconductor wafer dividing method according to the present invention will be described according to its procedure. In addition, FIGS. 1 and 2 are explanatory diagrams showing semiconductor wafers for each procedure, and the reference numeral 10 in these figures indicates a semiconductor wafer, and 11 indicates a semiconductor wafer.
is a semiconductor child knob.

First, a semiconductor wafer 10 to be divided is placed on the adhesive surface of a stretchable adhesive sheet 12 made of an ultraviolet curing resin or the like and bonded by thermocompression bonding. Note that this thermocompression bonding is performed by heating both of the superposed sheets on a real plate at 60 to 80° C. for 10 seconds, and then pressing both of them with a pressure roller.

Next, the L conductor wafer 1 to which the adhesive sheet 12 is attached
0 into the dicing device, and cut the semiconductor wafer 1 (with an uncut margin in the thickness direction at + (cutting dimension in FIG. 1) from 20 to Cutting with the dicing blade 13 is performed until the diameter of the cutting groove 14 is 60 μm.
form.

Note that the blade thickness of the dicing blade 13 in the dicing device used at this time is 20 to 30 μm, and the dicing speed is 50 to 0017 seconds.

Further, the semiconductor wafer 10 with the cut grooves 14 formed thereon is set in a laser device, and the bottoms of the dividing grooves 14 are irradiated with laser light, and the uncut portions of the cut 414 are melted and cut by this laser irradiation. A constant wave laser is used as the laser device 15, and the spot width and power of the laser beam are adjusted while checking the degree of cutting of the semiconductor wafer 10. However, as a guideline for the laser beam, the wavelength is 10 to 20 μm and the power is 0.5 to 1 watt. Note that the laser beam is poorly absorbed by the adhesive sheet 12, and even if the laser beam hits the adhesive sheet 12 strongly, no cut will be formed in the adhesive sheet 12.

In this way, the individual semiconductor chips 11 separated from the semiconductor wafer 10 are each peeled off from the adhesive sheet 12 and sent to the next process. Such a semiconductor chip 1
The divided surface 1 has an uneven surface 11a due to the uncut portion of the cutting groove 14 formed by the dicing blade 13 being cut by laser irradiation. Therefore, when manufacturing an HD type diode as shown in FIG. 3(a) using such a semiconductor chip 11, there are the following advantages. In other words, since the dividing surface of the semiconductor chip 20 that is not divided by the through-cut method (2) described above is flat, the semiconductor chip 20 cannot stand between the slug leads 21 and 21, as shown in FIG. 3(b). be(
(This is called pellet standing). However, in the semiconductor chip 11 divided by the method of the present invention, part of the dividing surface is an uneven surface 11a, so that such pellet standing is less likely to occur.

<Effects of the Invention> As described above, according to the present invention, a cut groove having an uncut portion is formed by cutting with a dicing blade, and then the uncut portion of the cut groove is fused by laser irradiation to form a semiconductor wafer. Divide. Therefore, it is possible to prevent the semiconductor chip from cracking or separating from the adhesive sheet. In addition, since the dicing blade never reaches the adhesive sheet, the dicing blade will not become clogged, and the adhesive sheet will not be cut by the dicing blade, so it will not tear even if the adhesive sheet is stretched. do not have. Moreover, since the time required for fusing processing by laser irradiation is short, the characteristics of the semiconductor chip are not deteriorated, and there is an effect that the occurrence of thermal cracks can be prevented.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing a semiconductor wafer in each step according to the method of the present invention. Also, Figure 3(a)
(b) is a cross-sectional view of a DHD type diode. DESCRIPTION OF SYMBOLS 10... Semiconductor wafer, 11... Semiconductor chip, 13... Dicing blade, 14... Cutting groove (groove).

Claims (1)

[Claims] (1) A method for dividing a semiconductor wafer, which comprises forming grooves in a semiconductor wafer by cutting with a dicing blade, and then fusing the semiconductor wafer by irradiating the bottom of the groove with a laser.