JPH0750810B2 - Method of cleaving semiconductor substrate - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaving a semiconductor substrate using a crystal cleavage plane.

2. Description of the Related Art The characteristics of semiconductor lasers are significantly affected not only by crystal growth techniques such as epitaxial growth, but also by the formation of reflectors on the cavity facets and other assembly techniques. The requirements for forming the reflecting mirror surface are firstly that the length of the semiconductor laser in the stripe direction (resonator length) can be controlled with good reproducibility, and secondly, there is no damage to the reflecting mirror forming portion.
Thirdly, it is possible to obtain a flat mirror surface of good quality, and thirdly, it is a technology that has excellent workability and can be used for mass production. In order to realize these conditions, the most commonly used method at present is to make a reflecting mirror surface by crystal cleavage, and the periphery of the epitaxially grown semiconductor substrate is pressed with a sharp blade along the cleavage surface of the crystal. It is obtained by

Problems to be Solved by the Invention In the above-mentioned semiconductor cleaving method, delicate work is required to obtain a good-quality flat mirror surface, and therefore, a large amount of work is required by a skilled worker. For this reason, variations such as the cavity length become large, and the reproducibility of the laser characteristics becomes poor. In addition, workability is poor, which may cause a decrease in yield,
It becomes a big problem in mass production.

Means for Solving the Problems In order to solve the above problems, the present invention provides a blade scratch at the cleavage position in the peripheral portion of a semiconductor substrate, and bonds this semiconductor substrate to a sheet having excellent stretchability coated with an adhesive. After that, the sheet is stretched in a direction perpendicular to the cleavage direction to generate a tensile stress in the semiconductor substrate, and in this state, the cleavage work is performed by hitting with a hammer from the direction perpendicular to the surface of the substrate.

Action According to the present invention, there is a fact that the cleavage property becomes very good under the generation of tensile stress to the semiconductor substrate due to the elongation of the sheet, and by adding a flaw to the peripheral portion of the semiconductor substrate, the cleavage position can be precisely determined. Can be controlled. For example,
In the case of a semiconductor laser, the obtained resonator length can be made constant by periodically making scratches at predetermined intervals. Further, by these, the force required from the direction perpendicular to the substrate surface at the time of cleavage can be significantly reduced, and therefore, the damage to the cleavage can be almost eliminated.

EXAMPLE An example in which the present invention is applied to an InP semiconductor laser will be described in detail with reference to the drawings.

FIG. 1 is a sectional view illustrating an embodiment of the present invention. The semiconductor substrate 1 used is the InP clad layer InGa on the InP substrate.
This is a wafer for a semiconductor laser in which four layers, an AsP active layer, an InP clad layer, and an InGa-AsP layer for facilitating ohmic contact are grown by a liquid phase epitaxial method. Au-based metal for electrodes on both front and back surfaces. Is vapor-deposited by about 1 μm. As shown in FIG. 2, on the surface of the epitaxial surface side of this wafer, a blade scratch 6 having a repeating pitch of 0.25 mm and a length of about 0.5 mm was formed on one side perpendicular to the cleavage direction <011> by a diamond cutter. The semiconductor substrate 1 is fixed on a stage that can be moved accurately by a stepping motor or the like, and a diamond cutter allows the interval between the blade scratches 6 to match a set target value with almost no error.

Next, the above-mentioned semiconductor substrate 1 was adhered to a vinyl chloride type sheet 2 with an adhesive 3, and the polyester type cover sheet 4 was further pressed onto the sheet, and a tensile force was mechanically applied in the direction of the arrow. The pulling direction is perpendicular to the cleavage direction <011>. In this state, when the semiconductor substrate 1 is gently struck in accordance with the blade scratch 6 by the hammer 5 that moves up and down, the semiconductor substrate 1 is cleanly cleaved at the position of the blade scratch 6. Under an appropriate tensile strength, the positions of the hammer 5 and the blade scratch 6 do not have to be exactly aligned, and if the initial position is adjusted, it can be easily automated by a normal automatic feeding mechanism.

FIG. 3 is a graph showing the yield of the cleaving process in the conventional cleaving method and the method of the present invention in order to investigate the effect of the present invention. In the conventional method, the yield is as low as 17 to 43%, whereas in the present invention, it is possible to improve the yield to 80% or more, and it is possible to solve the problems in workability so far. Furthermore, the method of the present invention has the feature that it can be easily expanded to automation and can be immediately put into mass production.

FIG. 4 is a comparison between the present invention and the conventional method regarding variations in the cavity length l, which is important for the characteristics of the semiconductor laser. In the conventional method, it is distributed over a fairly wide range due to manual work, but in the method of the present invention, it is almost equal to the target value, which shows that a uniform element can be obtained with good reproducibility. Also in this respect, the superiority of the present invention became clear.

In the embodiment of the present invention, the cleavage reflection surface of the semiconductor laser made of InP and InGaAsP is described, but it is needless to say that it can be applied to the semiconductor laser of other materials and other elements. The effect is obtained.

Effects of the Invention As described above, in the present invention, a high quality cleaved surface can be formed very easily with good reproducibility by a simple device,
If this method is applied to a semiconductor laser or other device, the manufacturing process can be greatly simplified and its industrial value is great.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining the constitution of an embodiment of the present invention, FIG. 2 is a plan view of a semiconductor substrate used for it, and FIG. 3 shows a yield in a cleaving process of a semiconductor laser in a conventional method and an embodiment of the present invention. FIG. 4 is a distribution characteristic diagram compared with FIG. 4, and FIG. 4 is a distribution characteristic diagram comparing variations in the cavity length of the semiconductor laser between the conventional method and the embodiment of the present invention. 1 ... Semiconductor substrate, 2 ... Sheet, 3 ... Adhesive, 4 ...
… Cover sheet, 5 …… Hammer, 6 …… Blade scratches.

Claims (1)

[Claims] 1. A step of making a blade scratch at a predetermined cleavage position in the peripheral portion of a semiconductor substrate, a step of adhering and fixing the semiconductor substrate on a stretchable sheet coated with an adhesive, and a step parallel to the surface of the semiconductor substrate. And, by pulling the elastic sheet in a direction perpendicular to the cleavage direction, in a state in which tensile stress is generated in the semiconductor substrate, by hitting the cleavage position from the vertical direction to the surface of the semiconductor substrate with a hammer, A method of cleaving a semiconductor substrate, comprising the step of cleaving the semiconductor substrate.