JPH0342508B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for cutting compound semiconductors forming light emitting devices.

(b) Conventional technology In order to improve luminous efficiency, conventional light emitting diodes use (111) planes for gallium phosphide (GaP), and (111) planes for gallium arsenide (GaAs) and potassium arsenide phosphide (GaAsP).
Pn junctions were formed on each of the 100 planes, but
When a Pn junction is formed on 100 sides of a wafer of these compound semiconductors, there are two (110) directions A and A as shown in Figure 1, and this is the complete cleavage direction, so generally from this direction or this direction Elements were formed by dicing in slightly deviated directions (approximately ±10°). However, at this time, the deeper the cutting blade cuts into the wafer 1 and the faster the cutting speed, the more chips (commonly known as chipping) 2, 2, etc. will occur at the edge of the cut portion, as shown in FIG. 3, 3... is difficult to form into a cube. Such chipping not only makes handling in a manufacturing jig inconvenient, but also affects the current distribution, light reflectance, and refractive index, resulting in a significant decrease in luminous efficiency in consideration of light extraction efficiency.

(c) Purpose of the invention The present invention has been made in consideration of the above points, and
The present invention provides a method for cutting a compound semiconductor, which has almost no effect on the cutting depth, can increase the cutting speed, and does not reduce luminous efficiency.

(d) Structure of the Invention The present invention is a method of cutting a compound semiconductor wafer in a direction sandwiched between two complete cleavage directions, and the present invention will be described in detail below based on examples.

(E) Embodiment Figure 3 is a side view of the main parts of a compound semiconductor wafer explaining an embodiment of the present invention.
A compound semiconductor wafer 6 having a Pn junction 5 is placed thereon, and grooves 7, 7, . . . are formed by a dicing method. This is because chipping 8 hardly occurs by advancing the dicing blade along the direction (B) (B) which is shifted by approximately 45 degrees from the complete cleavage direction in FIG. After that, pressure is applied from the back side of the sheet 4 to separate the elements, but whereas chipping in this process conventionally occurred several times as often as during cutting, in the present invention chipping occurs only a few tenths of the time during cutting. . After separation, the elements are peeled off from the sheet 4 using vacuum tweezers or the like. A specific example of such a cutting method will be shown. First, using GaAs as an example of a compound semiconductor, when examining the defective rate in only one direction along the cleavage direction, it was found that the above-mentioned chipping and the like did not occur at all.
However, since the cleavage directions of the crystal axes are not perpendicular to each other, it is necessary to provide vertical and horizontal grooves, which increases the defective rate. It is possible to align the two cutting directions with the cleavage direction and make the surface a parallelogram, but since the light emission distribution (brightness distribution) of light emitting diodes etc. depends on the element shape, it is generally roughly dice-shaped. A cubic shape is preferred, so that the cutting directions are approximately orthogonal. Below, when obtaining approximately cubic elements in a single wafer, excluding elements that cannot form a cube at the edge of the wafer, those with the above-mentioned chipping etc. in appearance are considered defective. The percentage is called the defective rate.

This defect rate is the worst when the position is slightly off from the cleavage direction, which is about 10%, which is ±30% from the cleavage direction.
It gradually improves until it deviates by a degree, reaching 7-8%. However, after that, the defective rate rapidly decreases, and the defective rate is lowest in the direction intersecting 40 to 50 degrees (±40 to ±45 degrees) with respect to the cleavage direction, and is about 2%. This tendency is considered to be a characteristic peculiar to the cutting of compound semiconductors with brittle crystals, since in silicon-based semiconductors, the failure rate did not change much whether the cleavage direction was crossed at 30 degrees or 45 degrees.

Furthermore, in compound semiconductors, even if there is no chipping on the outside, distortion may remain inside the crystal. As an example of this internal distortion, looking at the variation in the amount of light in a GaP red light emitting diode, the degree of variation is about ±20% when slightly shifted from the cleavage direction, and as the angle shift increases, the variation gradually increases. It became smaller, and when it crossed 45 degrees, it became about ±10%.

Therefore, in terms of both external defects and internal distortion, it is best to form a groove at an angle of about 45 degrees from the cleavage direction when cutting a compound semiconductor.

(f) Effects of the invention As described above, the present invention provides a method for producing compound semiconductor wafers.
This is a method of cutting compound semiconductors in which a Pn junction is formed on 100 planes, a groove is formed at an angle of about 45 degrees with respect to the complete cleavage direction of the crystal, and elements are separated based on the groove, making it easy to work in the post-process. , and the luminous efficiency is also good.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor wafer, FIG. 2 is a plan view of main parts of a wafer during conventional wafer cutting and separation, and FIG. 3 is a side view of main parts of a semiconductor wafer according to an embodiment of the present invention. 4... Sheet, 5... Pn junction, 1, 6... Wafer, 7, 7... Groove.

Claims (1)

[Claims] 1. A compound semiconductor cutting method characterized by forming Pn junctions on 100 faces of a compound semiconductor wafer, forming grooves inclined at approximately 45 degrees with respect to the complete cleavage direction of the crystal, and separating elements based on the grooves. .