JPH04262589A - Manufacture of optical semiconductor device - Google Patents

Abstract

PURPOSE:To automate cleavage, division of a laser diode wafer and to eliminate a crack, damage of the wafer, a pellet. CONSTITUTION:A cleavage inducing groove 3 is formed at an epitaxial layer growing surface side of a laser diode wafer l except an active stripe region 2 in a direction perpendicular to the stripe region by etching. A cleavage auxiliary groove 6 is dug at a substrate side of a rear surface by using a dicing saw. Substantially a center between the stripes 2 is cut by using the saw. A cleavage line is so run toward the active stripe region as to divide a chocolate rod.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical semiconductor device, and more particularly to a method for dividing a laser diode wafer.

0002

2. Description of the Related Art Unlike gas lasers and solid-state lasers, semiconductor lasers use parallel cleavage planes of the chip itself as resonator mirrors. A conventional method for forming a laser diode having this cleavage plane is as follows.

An active layer is formed on a compound semiconductor substrate by epitaxial growth or ion implantation. Since this epitaxial wafer has a thickness of several hundred μm including the thickness of the substrate, it is difficult to cleave it as it is. Therefore, the thickness is reduced to about 100 μm or less by polishing, and then metal vapor deposition, alloying, etc. are performed to form electrodes and the laser diode wafer is completed.

FIG. 8 is a perspective view [(a)] and a partial plan view [(b)] of a wafer formed in this manner.
Below, in the drawings (a) and (b), (a) is a perspective view and (
b) is a plan view]. In the figure, 1a is a laser diode wafer that has been polished to a thin finish, and 2 is an active stripe region.

In the next cleavage process, as shown in FIG. 9, one end of the wafer is scratched with a diamond point 11 or the like, and cleavage lines 9a are run by pushing the wafer one by one.
A rod-shaped wafer 10a with a cleavage plane parallel to the plane (FIG. 10)
make.

Thereafter, as shown in FIG. 10, the LD pellets 8 are made into individual pellets by making scratches using the same diamond point 11, and the final shape of the LD pellets 8 is shown in FIG.
get a.

[0007]

[Problems to be Solved by the Invention] The conventional manufacturing method described above has the following problems. First, in the conventional manufacturing method, the film thickness of the wafer is made extremely thin in order to facilitate cleavage, so as the wafer size increases, handling becomes difficult and wafer cracking is likely to occur.

[0008] Secondly, the process of running the cleavage line is mainly manual work because it is difficult to automate or introduce jigs, and this work requires great skill.

Thirdly, wafers, bar-shaped wafers, and pellets are handled more frequently with tweezers, leading to chipping defects and
The rate of appearance defects such as scratches increases.

0010

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the manufacturing process of the present invention: a step of digging a cleavage-inducing groove in a direction perpendicular to the stripes; ■ a step of machining a cleavage-assisting groove on the substrate side of the back side of the wafer so as to overlap the cleavage-inducing groove using a mechanical means such as a dicing saw; running a cleavage line toward the active stripe region in a chocolate break manner.

[0011] The active stripe regions are separated using mechanical separation means such as a dicing saw, and this step is set before or after the above step (2).

0012

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. 1 to 5 are a perspective view and a plan view for explaining a first embodiment of the present invention. The laser diode wafer 1 shown in FIG.
It is about 0 to 500 μm. First, a cleavage-inducing groove 3 perpendicular to the active stripe region 2 is formed on the epitaxial layer growth surface of this wafer by photo-etching. In this case, about 10 μm on each side of the active stripe region 2 is left unetched. In addition, cleavage inducing groove 3
Anisotropic etching is used to form the cross-sectional shape of an inverted triangle.

Next, as shown in FIG. 2, a double-sided alignment device used in the photolithography process is used to form cleavage auxiliary grooves for dicing on the substrate side (back side) of the wafer so as to overlap the cleavage inducing grooves. Form mark 4. At this time, pellet separation marks 5 are also simultaneously formed in the middle of the active stripe region.

Next, as shown in FIG. 3, using the auxiliary groove marks 4 and a dicing saw with a blade thickness of 20 to 30 μm, the back surface of the substrate is cut so that the remaining film thickness is 50 to 100 μm. Dig a cleavage auxiliary groove 6.

Next, as shown in FIG. 4, the wafer 1 is similarly divided along the pellet separation marks 5 using a dicing saw to form bar-shaped wafers 7.

Next, as when breaking chocolate, this rod is slightly bent in the direction a to widen the cleavage inducing grooves 3, and the cleavage line 9 is run toward the active stripe region 2 to separate the individual pieces as shown in FIG. Divide into 8 LD pellets. At this time, adhesive tape can be attached to the substrate side and used to divide the substrate. In this case, by stretching the adhesive tape a little at the same time as the division, it is possible to prevent the cleaved surfaces from scratching each other.

FIGS. 6 and 7 are perspective views for explaining a second embodiment of the present invention. In this example, after the same processing as in the first example is performed up to the stage shown in FIG.
In this state, the wafer is bent in the direction of the arrow a, and a cleavage line 9 is run across the wafer to divide it into rod-shaped wafers 10 having cleavage planes. Thereafter, it is separated into individual pellets using a dicing saw.

Compared to the first embodiment, the method of this embodiment does not change the process order from the conventional technology process, so it is suitable for products that require additional steps (for example, coating on cleaved end faces, etc.). This method has the advantage that this step can be carried out without changing the additional step.

[0019]

As explained above, in the present invention, cleavage is performed after forming a cleavage inducing groove on the epitaxial layer growth side of the wafer and a cleavage assisting groove on the back side of the wafer.
The following effects can be achieved. (2) Since the wafer has sufficient strength as a whole, cracking of the wafer can be prevented and its handling becomes easy. ■Since cleavage can be carried out using the chocolate break method, it does not require a high degree of skill to operate as in the case of conventional techniques. ■Since handling with tweezers can be eliminated throughout the entire process, appearance defects such as chips and scratches can be significantly reduced. ■Easier to automate work processes.

[Brief explanation of the drawing]

FIG. 1 is a perspective view and a partial plan view for explaining a first embodiment of the present invention.

FIG. 2 is a perspective view and a partial plan view for explaining a first embodiment of the present invention.

FIG. 3 is a perspective view and a partial plan view for explaining the first embodiment of the present invention.

FIG. 4 is a perspective view and a partial plan view for explaining the first embodiment of the present invention.

FIG. 5 is a perspective view and a partial plan view for explaining the first embodiment of the present invention.

FIG. 6 is a perspective view for explaining a second embodiment of the present invention.

FIG. 7 is a perspective view for explaining a second embodiment of the present invention.

FIG. 8 is a perspective view and a partial plan view for explaining a conventional example.

FIG. 9 is a perspective view and a partial plan view for explaining a conventional example.

FIG. 10 is a perspective view for explaining a conventional example.

FIG. 11 is a perspective view for explaining a conventional example.

[Explanation of symbols]

1, 1a Laser diode wafer 2 Active stripe region 3 Cleavage inducing groove 4 Cleavage auxiliary groove mark 5 Pellet separation mark 6 Cleavage auxiliary groove 7 Rod-shaped wafer 8, 8a LD pellet 9, 9a Cleavage line 10, 10a Rod-shaped with cleavage plane Wafer 11 Diamond Point

Claims (1)

[Claims] 1. A step of selectively etching the epitaxial growth surface of a wafer in which a laser diode is formed to form a cleavage-inducing groove orthogonal to the active stripe region in a shape that does not overlap the active stripe region, and A method for manufacturing an optical semiconductor device, comprising the steps of: forming a cleavage auxiliary groove overlapping the cleavage inducing groove by mechanical means; and performing cleavage at the cleavage inducing groove and the cleavage auxiliary groove.