JPH0983081A - Fabrication of semiconductor laser element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an active layer against damage due to cleavage by etching a trench deeper than the active layer in parallel with a stripe electrode, describing a scribe line in the trench in parallel with the stripe electrode, and then cleaving a substrate along the scribe line. SOLUTION: A trench 3 is etched between the rows of stripe electrodes (face orientation 011) 2 formed on the 100 crystal face of a substrate 1. A scratch 4 is made in the side part of substrate 1 by means of a scriber and the substrate 1 is cleaved at the position of scratch 4 thus obtaining a stripe laser bar 6. A scribe line 7 is then described on the bottom of trench 3 by means of a scriber. A sharp object, e.g. the edge of a cutter, is subsequently applied to the surface of laser bar 6 where the trench is not etched and the laser bar 6 is cleaved along the scribe line 7. According to the method, the active layer 5 of semiconductor laser element can be protected against damage due to cleavage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a method of manufacturing a high power semiconductor laser device suitable for laser radar.

[0002]

2. Description of the Related Art Generally, gas lasers such as He--Ne gas, solid-state lasers such as ruby, and semiconductor lasers using semiconductors are known as laser beams, depending on the device that generates them. A conventional method for manufacturing a semiconductor laser device will be described with reference to FIGS.

First, an insulating film and an electrode are formed on a substrate in which an active layer and a clad layer are single-crystal grown on a substrate such as GaAs, and then patterned and etched by a predetermined photolithography process to form a stripe electrode 31. Then, the semiconductor laser device forming substrate is manufactured.

After that, the side portion of the semiconductor laser element forming substrate is scratched and the wall is opened in a direction perpendicular to the stripe electrode 31 to manufacture a strip-shaped laser bar 30. This cleavage is performed along the crystal direction, and the cleavage surface 32 is formed into a mirror shape and used as a resonance surface.

Next, a scribe line 33 is inserted between the laser bar 30 and a scriber 34 in parallel with the stripe electrode 31 from the surface close to the active layer, and a cutter blade or the like is applied from below the scribe line 33. It is cleaved along the scribe line 33 to form one element. The cleavage plane parallel to the stripe electrode 31 does not become a mirror surface and therefore does not become a resonance surface.
The size of one element is about 500 μm × 500 μm.

[0006]

In the manufacturing process of the above-mentioned conventional semiconductor laser device, the scriber device is used.
There is a step of forming a groove in parallel with the stripe electrode. At that time, a scribe line is mechanically drawn at a depth of several μm using a sharp needle tip made of diamond or the like.

However, the active layer is located at a very close distance of 4 to 5 μm from the upper surface of the semiconductor laser device forming substrate,
By drawing this scribe line, the active layer will be damaged. This damaged area is apparently distant from the stripe electrode, but if the width of the stripe electrode is large, a current of several tens of amperes can be instantaneously passed through the element, for example, as in a high-power semiconductor laser element. In order to output a light output of 10 watts, the width of the stripe electrode must be 100 μm or more (30 μm or less for a low power semiconductor laser). In such a case, external stress applied to the active layer and crystals in the active layer are required. Defects easily propagate, which greatly affects the reliability of the device. Therefore, there is a problem that the deterioration of the element is accelerated and long-term reliability cannot be obtained.

When the laser bar 30 is fully scribed when the scribe line 33 is drawn,
In many cases, a defect portion 33a having a corner of the resonance surface 32 is generated, which not only causes a crystal defect in the active layer 35, but also causes thermal stress concentration during a thermal shock test, causing a crack from the defect portion 33a toward the inside. Occurs. As a result, there is a problem that the yield is remarkably reduced.

Further, when the cleavage is carried out in the same manner as when the resonance surface is formed, the elementized surface also becomes the resonance surface, and the laser light cannot be extracted from the front surface of the predetermined element.

Therefore, the present invention provides a method of manufacturing a semiconductor laser device, which prevents damage to the active layer due to cleavage of device division, and manufactures a semiconductor laser device having high output and high reliability for a long period of time. To aim.

[0011]

In order to achieve the above-mentioned object, the present invention is a semiconductor laser device forming substrate in which semiconductor laser device constituent elements including an active layer are laminated and formed on a semiconductor substrate, and a stripe electrode is provided at the top. A step of forming
A step of removing between the stripe electrodes to a depth at which the active layer is removed, and forming an etching groove, and a semiconductor laser device forming substrate in which the etching groove is formed,
Cleaving so as to form a resonance surface in a direction orthogonal to the column direction of the stripe electrode, a step of producing a strip-shaped laser bar, and a scribe line along the stripe electrode is drawn on the bottom of the etching groove of the laser bar. And a step of cleaving the semiconductor substrate along the scribe line and dividing the semiconductor laser element into individual semiconductor laser elements.

Further, the scribe line drawn on the bottom of the etching groove is drawn on the bottom of the etching groove so as not to reach the ends of the cleavage planes of the laser bar, and the region drawing the scribe line on the bottom of the etching groove is exposed. An insulating film and a metal film are stacked on the insulating substrate and the bottom of the etching groove, and a scribe line is drawn from the metal film to reach the semiconductor substrate.

In the method of manufacturing a semiconductor laser device according to the present invention as described above, when the semiconductor laser device forming substrate on which a plurality of devices are formed is cleaved to divide the semiconductor laser device into individual semiconductor laser devices, parallel to the stripe electrodes. An etching groove is formed to a depth exceeding the active layer, a scribe line is drawn in the groove in parallel with the stripe electrode, and cleavage is performed along the scribe line.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1A is a top view of a semiconductor laser device forming substrate on which a large number of semiconductor laser devices in the manufacturing process are formed as a first embodiment for explaining a method for manufacturing a semiconductor laser according to the present invention. The same figure (b) shows the front view. FIG. 2 shows a state in which a scribe line is provided on the semiconductor crystal substrate in a bar state, and FIG.
FIG. 3 is a diagram showing a cross-sectional structure of a semiconductor laser device separated into individual devices.

First, in FIG. 1A, a clad layer 10, an active layer 5, a clad layer 11, and a cap layer 12 are laminated on a semiconductor substrate 9 as shown in FIG. 3, and an insulating layer 13 is further formed thereon. 1 shows a semiconductor laser device forming substrate 1 on which a plurality of semiconductor laser devices in a manufacturing process in which a stripe electrode 2 is formed are formed. Although not shown, a lower electrode and a solder layer are formed on the back surface of the semiconductor laser device forming substrate 1.

The semiconductor laser device forming substrate 1 is formed on a crystal plane of 100 planes.

[Equation 1] Etching grooves 3 are parallel grooves formed between the rows of by etching. The etching groove 3 is formed to a depth of 4 to 5 μm, which is deeper than the active layer 5 of the semiconductor laser device. The etching groove 3 may be formed by either a wet etching method or a dry etching method.

Then, the semiconductor laser device forming substrate 1
A scratch 4 is formed on the side of the scriber by a scriber, and cleavage is performed from the position of the scratch 4 to obtain a strip-shaped laser bar 6. The cleavage plane 8 at this time becomes a resonance plane. Next, in this laser bar 6, a scribe line 7 is formed at the bottom of the etching groove 3 with a scriber.

Here, if the position where the scribe line 7 is drawn starts from a position separated by 30 μm or more from each resonance surface 8, each semiconductor laser element can be well separated without being chipped.

The scribe line 7 is shown in FIG.
As shown in FIG. 7, if the relationship between the resonator length a of the laser and the scribe line length b satisfies the following relationships: b / a ≧ 0.5, (ab) / 2 ≧ 30 μm, good device isolation can be achieved. it can.

Next, a sharp object such as a blade of a cutter is pressed against the surface of the laser bar 6 facing the surface where the etching groove 3 is present, and cleavage is performed along the scribe line 7 to obtain one semiconductor laser element. At this time, the etching groove 3
Is formed deeper than the active layer 5, so that portion does not serve as a resonance surface.

By the manufacturing method described above, the active layer 5 of the semiconductor laser device can be provided with an extremely highly reliable device without any mechanical damage.

In this embodiment, the insulating layer 13 and the stripe electrode 2 are patterned by a photolithography process so that the semiconductor substrate 9 is exposed so that the scribe line 7 is not covered by the scriber needle. The scribe line 7 can be easily inserted.

The light emitting region 14 in the active layer 5 corresponds to the stripe width, and the stripe width is 4 in this embodiment.
00 μm, element width 600 μm, resonator length 500 μm
And

Next, as a second embodiment for explaining the method of manufacturing a semiconductor laser according to the present invention, the structure of a semiconductor laser device is shown in FIG. 4 and described.

In the above-described first embodiment, the semiconductor substrate 9 is exposed at the position where the scribe line 7 is drawn, but in the present embodiment, the insulating film 17 covers the element region up to the position of the scribe line 7, It is reliable.

When the scribe line 7 is drawn on the insulating film 17, since the insulating film 17 is made of SiO2, Si3 N4 or the like, the scriber needle slides, so that the insulating film 1
An Au film to be the stripe electrode 16 is simultaneously formed on the electrode 7, and the needle of the scriber is made to bite from the surface of the electrode 16 so as to pass through the insulating film 17 and into the semiconductor substrate 9.
It is possible to describe the scribe line.

In this embodiment, the same effect as that of the above-described first embodiment can be obtained.

Next, as a third embodiment for explaining the method for manufacturing a semiconductor laser according to the present invention, the structure of a semiconductor laser device is shown in FIG. 5 and described.

In the above-described second embodiment, the Au film also serving as the stripe electrode 16 is formed on the insulating film 17, but when the adhesion strength between the insulating film 17 and the Au film is small, the scribe line 7 is drawn. If the semiconductor laser device is divided into one semiconductor laser device, the Au film at the cut surface may be peeled off from the insulating film 17.

Therefore, in the third embodiment, after the insulating film 17 is formed as in the second embodiment, the scriber needle bites into only the region where the scribe line is drawn, separately from the stripe electrode 16. Such a metal stripe 18 is also formed when the stripe electrode 2 is formed. However, the metal stripe 18 need not be the same material as the stripe electrode 2.

The method for manufacturing a semiconductor laser according to the present invention is not limited to the above-described embodiment, and stripes are formed in a direction orthogonal to the stripe electrode 2 on the surface having the plane orientation 100 described in the embodiment. The electrodes may be formed.

Further, in this embodiment, the stripe width is 4
Although it is set to 00 μm, the stripe width is not particularly limited. Therefore, the present invention may be applied to not only pulse-driven high-power semiconductor lasers but also direct-current (CW) semiconductor lasers with a small stripe width.

As a method of using an etching groove for cleaving a semiconductor laser, there is one disclosed in Japanese Patent Publication No. 59-14914, which is one in which an etching groove is formed in a resonance surface. The subject of the present invention,
Regarding cleavage for forming an element in a direction parallel to the stripe electrode, cleavage is performed by a method similar to that described in the related art. Therefore, the operation and effect of the present invention cannot be obtained with this conventional technique.

Further, as a scribe line for cleaving the semiconductor laser from the position away from the resonance surface,
There is one described in Japanese Patent Publication No. 1-41268, which describes a scribe line from the back surface side (the side opposite to the upper electrode) of the element formation surface of the semiconductor substrate, and is essentially No mechanical damage to the active layer can be ruled out. Therefore, the operation and effect of the present invention cannot be obtained with this conventional technique.

As described above, according to the present embodiment, the active layer is formed in parallel with the stripe electrodes in the cleavage for dividing the semiconductor laser device forming substrate on which a large number of devices are formed into individual semiconductor laser devices. An etching groove is formed to a depth to be removed, a scribe line is drawn in the groove in parallel with the stripe electrode, and cleavage is performed along the scribe line to prevent damage to the active layer at all and to obtain a single semiconductor laser. It can be divided into elements.

Further, according to the present embodiment, since the resonance surface and side portions are trapezoidal (mesa) shaped, there is no chipping during cleavage, and excessive thermal stress concentration does not occur during a thermal shock test. Further, it is possible to supply a highly reliable semiconductor laser device and improve the yield.

In the semiconductor laser device forming substrate,
Since the semiconductor substrate is exposed, the scribe line can be easily drawn in the substrate with the diamond needle of the scriber device.

Even when an insulating film is formed on a semiconductor substrate and a scribe line of the insulating film is drawn, a metal film for an electrode is formed on the insulating film and a diamond needle is written on the metal film. This makes it possible to easily form a scribe line in the semiconductor substrate through the insulating film.

When a semiconductor laser device is formed by using the method for manufacturing a semiconductor laser of the present invention, it is suitable for a high-power semiconductor laser having a light emitting region width of 100 μm or more in the active layer and a large stripe width. The device can be surely formed.

[0041]

As described in detail above, according to the present invention, a semiconductor laser which prevents damage to the active layer due to cleavage of device division and produces a semiconductor laser device having high output and high reliability for a long period of time. A method for manufacturing an element can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor laser device forming substrate on which a large number of semiconductor laser devices for carrying out a first embodiment of the present invention are formed.

FIG. 2 is a diagram showing an example in which slive lines are drawn on a laser bar manufactured from the semiconductor laser device forming substrate shown in FIG.

3 is a diagram showing a cross-sectional structure of one semiconductor laser device obtained by dividing the semiconductor laser device forming substrate shown in FIG.

FIG. 4 is a diagram showing a cross-sectional structure of a semiconductor laser device for explaining a second embodiment according to the present invention.

FIG. 5 is a diagram showing a cross-sectional structure of a semiconductor laser device for explaining a third embodiment according to the present invention.

FIG. 6 is a view showing a substrate on which a plurality of semiconductor laser devices are formed for explaining a conventional method for manufacturing a semiconductor laser device.

FIG. 7 is a diagram showing a configuration of one divided semiconductor laser device for explaining a conventional method for manufacturing a semiconductor laser device.

[Explanation of symbols]

1 ... Semiconductor laser element forming substrate, 9 ... Semiconductor substrate, 2 ...
Stripe electrode, 22 ... Etching groove, 5 ... Active layer, 1
0, 11 ... Clad layer, 12 ... Cap layer, 13 ... Insulating film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriyuki Matsushita 1-1, Showa-cho, Kariya city, Aichi prefecture

Claims (4)

[Claims] 1. A step of forming a semiconductor laser device constituent element including an active layer on a semiconductor substrate in a laminated manner to form a semiconductor laser device forming substrate having a stripe electrode on an uppermost portion, and the active layer is provided between the stripe electrodes. Removing to a depth to be removed and forming an etching groove; and cleaving the semiconductor laser device forming substrate having the etching groove formed so as to form a resonance surface in a direction orthogonal to the column direction of the stripe electrodes. Then, a step of manufacturing a strip-shaped laser bar, at the bottom of the etching groove of the laser bar, draw a scribe line along the stripe electrode, and cleave the semiconductor substrate along the scribe line, individual semiconductor laser element A method of manufacturing a semiconductor laser, comprising: 2. The method of manufacturing a semiconductor laser according to claim 1, wherein the scribe line drawn on the bottom of the etching groove is drawn on the bottom of the etching groove so as not to reach the ends of the cleavage planes of the laser bar. . 3. The method of manufacturing a semiconductor laser according to claim 1, wherein the semiconductor substrate is exposed in a region that draws a scribe line at the bottom of the etching groove. 4. An insulating film and a metal film are laminated on the bottom of the etching groove that draws the scribe line, and the scribe line is drawn so as to reach the semiconductor substrate from the metal film. The method of manufacturing a semiconductor laser according to claim 1, wherein