JPS5847856B2 - Semiconductor wafer separation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor wafer separation force method for separating a semiconductor wafer into a plurality of pellets.

Conventionally, in order to separate a semiconductor wafer on which a large number of semiconductor elements are formed into pellets for each element, the wafer is previously fixed on a table using a vacuum chuck.

Next, separation grooves of a predetermined depth are bored vertically and horizontally along the pellet separation area using a diamond cutter, a diamond blade, a laser scriber, etc., and these grooves are placed on a table 1 made of a soft material as shown in FIG. The wafer 4 is placed face down on a wafer, an elastic member 2 such as a rubber mat is provided on the back side, and a roller 3 is rolled on the surface of the elastic member 2 to separate the wafer 4.

This method is based on the so-called wafer cracking (breaking) method in which the separation grooves 4aK are formed and the wafers 4 are separated by the rollers 3. Although the apparatus is simple, when the separation grooves 4aK are separated into pellets by the rollers 3, the pellets are When the corners of the pellets disintegrate or collide with each other, cracks and chips occur in the pellets.

Furthermore, there is a drawback that it is not suitable for separating thick wafers 4 or large-diameter wafers 4 due to dependence on crystal orientation.

The present invention has been made in view of these points, and is a semiconductor wafer that can easily separate the wafer into pellets of a desired shape while preventing the pellets from cracking or chipping using an easy-to-operate and inexpensive device. They discovered a separation method.

The method of the present invention will be explained below.

In the method of the present invention, a separation groove of a predetermined shape is drilled in advance on the surface of a semiconductor wafer along a pellet separation area, and then a separation liquid is injected into the separation groove to solidify and expand. It separates a semiconductor wafer into a large number of parts.

Here, the shape of the separation groove is such that the width of the groove serving as the cutting margin is small in order to increase the number of edges per wafer.

It is usually desirable to set the groove width to 40 to 100 μm.

The depth of the groove is desirably set to 1/2 to 9/10 of the thickness of the wafer so that pellets can be easily separated by expansion of the separating liquid.

Any means such as a separation groove, a diamond cutter, a diamond blade, a laser scriber, etc. may be used.

The separating liquid may be any liquid, such as water, that can easily solidify by cooling and expand its volume more than when it is in a liquid state.

Next, examples of the present invention will be described.

As shown in Figure 2, 10 or 1 2 x 2 semiconductor pellets
A semiconductor wafer 11 with a diameter of 76 µm and a thickness of 0.3 m was formed with a diamond blade in advance along the pellet separation area with a groove width of 40 μm and a groove depth of 200 μm.
Ten sheets having separation grooves 12 were prepared.

Water was sprayed as a separation liquid 13 onto the surfaces of these semiconductor wafers 11, and the water was injected into the separation grooves 12 by capillary action.

Thereafter, the semiconductor wafer 11 was placed on a tray 14 having a mesh shape of approximately 500 μm, as shown in FIG.
It was housed in wafer boat 15.

Next, the wafer boat 15 was immersed in liquid nitrogen set at about -200°C for about 5 minutes.

After the immersion process, the tray 14 was pulled out from the wafer boat 15 and the state of separation of the pellets 10 was observed. As shown in FIG. 4, all the pellets 10 were completely separated without any damage such as cracks or chips. This was confirmed.

Incidentally, when the pellets 10 were taken from the saucer 14 and the change in mass of the saucer 14 before and after the separation of the semiconductor wafers 11 was examined and the mass of cracks and chips was measured, it was found to be O g.

As described above, according to the force method of the present invention, as shown in FIG. The semiconductor wafer 11 can be easily separated into pellets 10 by generating cracks from the wafer 10 and applying a uniform expansion force F in any direction.

Furthermore, when separating the pellets 1 and 10, no external force is applied, and since ice 13a exists between the pellets 10, adjacent pellets 10 do not collide with each other and cause cracks or chips. It can be prevented.

Further, contamination of the semiconductor wafer 11 by the separation liquid 13 made of water or the like is prevented, and since separation operation using an external force such as a roller is not required, work efficiency can be improved with a simple structure and an inexpensive device.

Incidentally, for comparison with the example, a similar semiconductor wafer 4 was prepared.
When separation grooves 4a were formed on the 0 sheets using a diamond blade and the pellets were separated using the roller 3 shown in FIG. It was 847 ng.

Also, compared to this comparative example, the yield in the example was about 5%.
It turns out that there has been a % improvement.

As explained above, according to the separation force method for semiconductor wafers according to the present invention, it is possible to easily separate wafers into pellets of a desired shape by using inexpensive equipment and simple operations, while preventing pellets from cracking or chipping. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the conventional separation force method for semiconductor wafers, Fig. 2 is a perspective view of a semiconductor wafer, Fig. 3 is a perspective view of a ueno boat used in the method of the present invention, Fig. 4 FIG. 5 is a cross-sectional view of a pellet separated by the method of the present invention, and FIG. 5 is an explanatory diagram showing the action of the separation liquid in the method of the present invention. 10...Pellet, 11...Semiconductor wafer, 12...Separation groove, 13...Separation liquid, 18...Crack.

Claims (1)

[Claims] 1. A separation groove of a predetermined shape is drilled on the surface of a semiconductor wafer along a pellet separation area for separating the wafer into pellets of a predetermined shape, and then a separation liquid is injected into the separation, and after that, A method for separating semiconductor wafers, comprising solidifying and expanding the separating liquid to separate the wafer into a large number of pellets.