JPH0750811B2 - Cleaving method of semiconductor laser - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaving a semiconductor laser, which is effective for forming a laser cavity reflecting surface.

2. Description of the Related Art A semiconductor laser is an important element at the core of optical fiber communication, and its demand is rapidly increasing as the market in the optoelectronics field grows. Recently, as a light source for an optical disk or the like, it has been incorporated into a consumer device, and the number of products produced has increased dramatically, and demands for cost and reliability have also become strict.

A semiconductor laser is composed of two components: a light amplification function by current injection using a double heterojunction and a light reflection function by a resonator reflection surface, that is, a light feedback function. A crystal cleavage plane is used. As a method for forming a cleaved surface of a semiconductor laser, in many cases, a method in which a sharp edged tool is strongly pressed along the cleavage direction from the peripheral portion of an epitaxial wafer to perform crystal cleavage, and in this case, the force applied is The strength and the direction have to be finely adjusted, and it depends largely on the manual work of an expert.

Problems to be Solved by the Invention The characteristics of the semiconductor laser are significantly affected not only by the crystal growth technique such as epitaxial growth but also by the quality of the cleavage plane formation method and other assembly techniques. The method is required to reduce damage to the cleaved portion, obtain the length of the semiconductor laser in the stripe direction (cavity length) with good reproducibility, and have good workability and excellent mass productivity. It is something. However,
In the above-mentioned conventional method, the force applied to the crystal by the sharp blade is large, and damage to the cleaved portion is not small. Moreover, even a skilled person is unlikely to obtain a flat cleaved mirror surface and is extremely inferior in workability. Further, since the work is done by hand, there is a large variation in the cavity length, and it is difficult to make the characteristics of the obtained semiconductor laser uniform.

In order to solve these problems, an object of the present invention is to provide a cleaving method for a semiconductor laser, which has less damage to the cleaved surface and has good workability.

Means for Solving the Problems The present invention provides a first step of making a scratch on a cleavage plane forming position in a peripheral portion of a semiconductor laser substrate, and a first step of making the substrate adhesive.
A second step of adhering and fixing to a sheet; a step of holding the base adhered and fixed to the first sheet on a stretchable second sheet; and a direction perpendicular to the substrate surface, in accordance with the blade scratch, And a step of cleaving the substrate from above the first sheet to cleave the substrate, the method of cleaving a semiconductor laser.

Effect According to the present invention, in addition to the striking force, the repulsive force from the stretchable second sheet is applied to the base in an overlapping manner, so that a stress that pushes the cleavage surface acts and blade damage is caused. Cleavage of the crystal substrate as the starting point is facilitated. Further, the striking force on the base body may be appropriately reduced by taking into account the repulsive force from the second sheet, so that damage to the base body surface, particularly the cleavage surface can be reduced.

Examples Next, the present invention will be described with reference to Examples. Fig. 1 a, b,
FIG. 3C is a schematic view of process order of the embodiment of the present invention. First, the first
As shown in the schematic plan view of FIG. 1A, a blade scratch 2 of a predetermined length formed by a diamond cutter is attached to the cleavage position of the peripheral portion of the substrate 1 of the epitaxial wafer. Second, as shown in the schematic cross-sectional view of FIG. 1B, the substrate 1 of this epitaxial wafer is covered with a thin cover sheet 3 made of polyethylene on the upper surface of the substrate 1, and the lower surface side is made of a slightly thick vinyl chloride-based material. The sheet is adhered and fixed by the adhesive sheet 4 coated with the adhesive 5. Thirdly, as shown in FIG. 6C, the sheet 4 is placed on the upper side, the base 1 is held on the elastic sheet 6 having excellent elasticity, and the hammer 7 for hitting is pressed from a position perpendicular to the surface of the base. By this, the cleavage can be easily performed.

The operation of the present invention in the above configuration will be described with reference to the schematic sectional view of FIG. When the hammer 7 is pressed from the adhesive sheet 4 side so that the force applied to the substrate 1 of the epitaxial wafer becomes perpendicular to the substrate 1, the elastic sheet 6 causes a repulsive force in a direction opposite to the applied force. . Due to this repulsive force, the base body 1 is bent, and bending stress is generated inside the surface on which cleavage is to be performed. At this time, regarding the bending stress and the repulsive force, due to the lever principle, even if a small repulsive force, that is, the force applied by the hammer 7 is small, the stress generated inside can be increased and the cleavage is facilitated. The blade scratches 2 provided on the side of the stretchable sheet 6 on the base body 1 act as the starting points of the cleavage, and the bending stress necessary for the cleavage can be reduced, so that the cleavage occurs exactly at the positions of the blade scratches 2 provided in advance. Due to the above-mentioned overall effect, the substrate 1 of the epitaxial wafer can be accurately cleaved at the position of the blade scratch 2 by applying a very slight force. If the above operation is performed without applying the pressure sensitive adhesive 5 to the pressure sensitive adhesive sheet 4, that is, without adhering and fixing the substrate 1, the force is dispersed when the cleavage plane interval is small, and the effect of the present invention is sufficiently obtained. Is not demonstrated to

In the present invention described above, the applied force can be effectively used for the cleavage surface and the introduction of unnecessary force can be removed, so that no damage is generated on the formed cleavage surface, and a good mirror surface is obtained. It can be obtained with good reproducibility.

An example in which the present invention is applied to a semiconductor laser using InP and InGaAsP as materials will be described in more detail.

The substrate 1 of the epitaxial wafer is a InP clad layer, an InGaAsP active layer, an InP clad layer, and four InGaAsP layers for improving ohmic contact of electrodes grown on a InP substrate by a liquid phase epitaxial method. Thickness is about 100μ
The Au-based metal for electrodes is vapor-deposited on the P-type and n-type surfaces. As shown in FIG. 1a, on the surface of the substrate 1 on the epitaxial growth side, a blade scratch 2 having a repeating pitch of P = 0.25 mm and a length of about 0.5 mm is formed on one side of the periphery perpendicular to the cleavage direction <O11>. Was formed by a diamond cutter. In this step, the substrate 1 of the epitaxial wafer described above is used.
Is fixed on a stage that can be accurately translated by a stepping motor or the like, and the interval between the blade scratches 2 due to the diamond cutter can match the set target value with almost no error.

Next, as shown in FIG. 1B, the substrate 1 of the above-mentioned epitaxial wafer is adhered and fixed to a vinyl chloride-based adhesive sheet 4 coated with an adhesive 5 to prevent peeling during cleavage. The upper part was pressed with a thin polyester sheet 3 for cover. Further, the vinyl chloride-based pressure-sensitive adhesive sheet 4 to which the substrate 1 was fixed was held on a stretchable sheet 6 made of silicon rubber having excellent stretchability as shown in FIG. 1c. In this embodiment, the elastic sheet 6 is stretched in a direction perpendicular to the cleavage direction in order to increase the elasticity of the elastic sheet 6 made of silicone rubber and increase the repulsive force.
In this state, when the hammer 7 for striking was pressed gently in accordance with the blade scratch 2, the base body 1 was cleanly cleaved at the position of the blade scratch 2. Due to the presence of the blade scratch 2, the force required for cleavage is significantly reduced.
Even if the position is slightly deviated, there is no problem and the cleavage occurs at the position of the blade scratch 2. This fact indicates that if the initial position is adjusted sufficiently, the cleavage process can be easily automated by using a normal automatic feeding mechanism, which can be a great advantage in terms of mass production.

FIG. 3 illustrates the yield in the cleavage step in the conventional cleaving method and the method of the present invention in order to investigate the effect of the present invention. While the conventional method has a low value of 38% to 50%, the method of the present invention has a yield of 67 to 84%, which can improve the yield by about 30%, and it has been possible to solve the problems in workability so far. As described above, the method of the present invention 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, which are important for the characteristics of the semiconductor laser. In the conventional method, it was impossible to make the resonator length uniform by distributing it in a fairly wide range due to manual work, but in the method of the present invention, it is possible to obtain a uniform element with good reproducibility, which is almost equal to the target value. Becomes Also in this respect, the superiority of the present invention became clear.

Further, according to the method of the present invention, the flatness of the obtained cleavage plane is very good, the variation with respect to the outgoing light angle can be reduced, and further, the force applied at the time of cleavage is small, so that the point of reliability is high. However, excellent elements have been realized. In addition, in the embodiment of the present invention, the formation of the cleavage plane of the InP semiconductor laser has been described, but it is of course applicable to the semiconductor laser of other materials such as Ga Al As, and the same effect can be obtained.

EFFECTS OF THE INVENTION As described above, according to the present invention, a high quality cleaved surface can be formed reproducibly and very easily by a simple device, and its industrial value is great.

[Brief description of drawings]

1A to 1C are schematic views in order of steps showing an embodiment of the present invention, FIG. 2 is a schematic sectional view for explaining a process of the embodiment of the present invention,
FIG. 3 is a characteristic diagram comparing the yield in the cleaving process of the semiconductor laser between the present invention and the conventional method, and FIG. 4 is a characteristic diagram comparing the variation in the cavity length of the semiconductor laser between the present invention and the conventional method. . 1 ... Substrate, 2 ... Blade scratch, 3 ... Cover sheet, 4 ...
... Adhesive sheet, 5 ... Adhesive, 6 ... Stretchable sheet (silicone rubber), 7 ... Hammer.

Claims (1)

[Claims] 1. A first step of making a blade scratch on a cleavage surface forming position of a peripheral portion of a semiconductor laser substrate, a second step of adhesively fixing the substrate to an adhesive first sheet, and the first sheet. Holding the adhesively fixed base body on a stretchable second sheet; and cleaving the base body from above the first sheet in a direction perpendicular to the surface of the substrate in accordance with the blade scratches to cleave the base body. A method of cleaving a semiconductor laser, comprising: