JPS62296579A - Cleavage of semiconductor substrate - Google Patents

Abstract

PURPOSE:To form an excellent cleavage plane extremely easily with superior reproducibility by forming an edge flaw at the position of cleavage of the periph eral section of a semiconductor substrate, bonding the semiconductor substrate with a sheet having excellent stretching properties and stretching the sheet. CONSTITUTION:A substrate 1 is fixed onto a stage precisely moved by a stepping motor, etc., and the intervals of edge flaws 6 by a diamond cutter can be conformed to a target value set approximately without errors. The substrate 1 is stuck to a vinyl chloride group sheet 2 by pressure sensitive adhesives 3, the upper section of the substrate 1 is pressed down by a polyester group sheet 4, tensile force is applied mechanically in the direction of the arrow, and the tensile direction is directed in the direction rectangular to the direction of cleavage. When the semiconductor substrate 1 is struck slowly, conformed to the edge flaws 6 by a vertically movable hammer 5 for striking under the state, the substrate 1 is cloven accurately at the positions of the edge flaws 6.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a method for interfolding a semiconductor substrate using a pre-crystal open plane.

BACKGROUND OF THE INVENTION Characteristics of semiconductor lasers are significantly influenced not only by crystal growth techniques such as epitaxial growth, but also by the formation of mirrors on the cavity end faces and other assembly techniques. What is required when forming a reflective mirror surface is, firstly, that the length of the semiconductor laser in the stripe direction (cavity length) can be controlled with good reproducibility, and secondly, that there is no damage to the reflective mirror forming part.
The third advantage is that a flat mirror surface of good quality can be obtained, and the third advantage is that the technique has excellent workability and can be used for mass production. To achieve these conditions, the most commonly used method at present is to create a reflective mirror surface between the crystal folds, by cutting the periphery of the epitaxially grown semiconductor substrate along the interfold plane of the crystal with a sharp knife. Obtained by pressing.

Problems to be Solved by the Invention The above-mentioned semiconductor fold-spacing method requires delicate work in order to obtain a good quality flat mirror surface, and therefore relies heavily on the manual work of skilled workers. For this reason, variations in the resonator length, etc. become large, and the reproducibility of laser characteristics becomes poor. In addition, workability is poor (and may cause a decrease in yield).
This becomes a big problem during mass production.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method in which a blade is made at the cleavage position on the periphery of a semiconductor substrate, the semiconductor substrate is bonded to a highly stretchable sheet, and then the sheet is stretched. In this method, tensile stress is generated in the semiconductor substrate, and in this state, the interfold work is performed by striking the substrate surface in a direction perpendicular to the substrate surface.

According to the present invention, there is a fact that the crease property is very good when tensile stress is generated on the semiconductor substrate due to sheet elongation, and by adding scratches to the periphery of the semiconductor substrate, the cleavage position can be precisely adjusted. can be controlled. For example, in the case of a semiconductor laser, by periodically making scratches at predetermined intervals, the resulting resonator length can be made constant. Moreover, these can significantly reduce the force required in the direction perpendicular to the substrate surface during inter-folding, and therefore, damage to the inter-fold portion can be almost eliminated.

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

FIG. 1 is a cross-sectional view illustrating the present invention in detail. The semiconductor substrate 1 used was for a semiconductor laser, in which four layers of an InP cladding layer, an nGaAsP active layer, an InP cladding layer, and two InGa-As layers for facilitating ohmic contact were grown on an InP substrate by a liquid phase epitaxial method. It is a wafer with about 1 layer of Au-based metal for electrodes on both the front and back surfaces.
The thickness is about μm. As shown in FIG. 2, on the surface of this wafer on the epitaxial side, a repeating pitch of 0.25 mm on one side perpendicular to the cleavage direction <011> and a length of approximately 0.
, 5 mm blade scratches 6 were formed using a diamond cutter.

The substrate 1 is fixed on a stage that is accurately movable by a stepping motor or the like, and the intervals between the blade scratches 6 made by the diamond cutter are made to coincide with a set target value without any error.

Next, the above-mentioned substrate 1 was attached to a vinyl chloride sheet 2 with an adhesive 3, and the top was further pressed with a polyester sheet 4, 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 with the vertically movable hitting hammer 5 in line with the blade scratches 6, the substrate 1 is neatly folded at the position of the blade scratches 6. Under appropriate tensile strength, the positions of the hammer 5 and the blade scar 6 do not need to match exactly, and as long as the initial position is adjusted, it can be easily automated using a normal automatic feeding mechanism.

FIG. 3 is a graph showing the yield of the inter-fold process using the conventional cleavage method and the method of the present invention, in order to examine the effects of the present invention. While the conventional method has a low yield of 17 to 43%, the present invention can improve the yield to over 80% and solve the previous problems with workability. 'Furthermore, the method of the present invention has the advantage that it can be easily extended to automation, so it can be immediately transferred to mass production.

FIG. 4 compares the variation in the cavity length e, which is important for the characteristics of a semiconductor laser, between the present invention and the conventional method. In the conventional method, the distribution is over a fairly wide range due to manual work, but in the method of the present invention, the value is almost equal to the target value, indicating that homogeneous elements can be obtained with good reproducibility. The superiority of the present invention has also become clear in this respect.

In the embodiments of the present invention, InP and InGaAs
Although the interfold reflection surface of a semiconductor laser made of P is described, it is of course applicable to semiconductor lasers made of other materials and other devices, and similar effects should be obtained.

As described in detail, the present invention allows high-quality interfold surfaces to be formed extremely easily with good reproducibility using a simple device, and when this method is applied to semiconductor lasers and other devices, the manufacturing process can be improved. can be greatly simplified, and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating the configuration of an embodiment of the present invention, FIG. 2 is a plan view of a semiconductor substrate used therein, and FIG. 3 is a graph showing the yield in the inter-fold process of a semiconductor laser compared to the conventional method and the embodiment of the present invention. FIG. 4 is a distribution characteristic diagram comparing the conventional method and the embodiment of the present invention with respect to variations in the cavity length of a semiconductor laser. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Vinyl chloride sheet, 3... Adhesive, 4... Polyethylene sheet for cover, 5... Hammer for hitting the board, 6...Blade scratches formed with a diamond cutter. Name of agent: Patent attorney Toshio Nakao (1 person) 1st cause Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A first step of making a knife wound at a predetermined cleavage position on the periphery of the semiconductor substrate, and a second step of adhesively fixing the semiconductor substrate onto a stretchable sheet coated with an adhesive; By striking the cleavage position from a direction perpendicular to the substrate surface while generating a tensile stress through the stretchable sheet in a direction parallel to the surface and perpendicular to the cleavage direction. A method for cleaving a semiconductor substrate, the method comprising cleaving a semiconductor substrate.