JPH02119284A - Formation of protective film for semiconductor laser end face - Google Patents

Abstract

PURPOSE:To prevent creeping of a protective film to a mount surface without a rectangular jig to be inserted between semiconductor laser bars by closely arranging a plurality of semiconductor bars with the light emitting end face tilted and up on a flat supporting base and by depositing an insulating film. CONSTITUTION:Fixing jigs 3a, 3b are provided with an inclination of about 12 deg., and a plurality of semiconductor laser bars 1 are inserted therebetween in lamination with an electrode 6a at a side of a light emitting region 5 on the left side and fixed to a flat supporting base 4. A protective film is formed to an upper end side 7a on the semiconductor laser bar from an upper part through sputtering, etc. Then, a protective film is formed with a lower end side 7b up. According to this constitution, a protective film of a uniform film thickness can be formed all over the end side, thereby preventing creeping of the protective film on a mount surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming a protective film on a light emitting end face of a semiconductor laser.

[Conventional technology]

Generally, semiconductor lasers have a width of 3 mm, as shown in Figure 4.
The light emitting region 5, which is a rectangular parallelepiped with a cavity length of 300 μm and a thickness of about 100 μm, is 10 μm away from the electrode 6a on one side.
m, and the light emitting end face (hereinafter referred to as end face) >7a
and 7b contains 5i02 to prevent surface oxidation.
A protective film such as the following is formed. The thickness of the protective film is, for example, λ/2 where the refractive index of the film is n and the wavelength of the laser is λ.
The thickness is determined to be a predetermined value, such as n. The formation of this protective film is
-m, as shown in FIG. 5, a bar with a length of about 2 cm before being pelletized is formed with semiconductor lasers connected in the horizontal direction.

As can be seen from Figure 3, which shows the conventional method for forming a protective film, in the conventional method, a semiconductor laser bar 1 in which a plurality of semiconductor lasers are connected and a rectangular parallelepiped jig 2 that is about the same length or slightly longer than the bar are used. A plurality of them were stacked alternately, and both ends thereof were sandwiched between fixing jigs 3 and fixed to a flat support base 4, and a protective film was formed by sputtering or the like from perpendicularly above the flat support base. At this time, if the height of the rectangular parallelepiped jig 2 in contact with the electrode 6a on the light emitting region side of the semiconductor laser bar 1 is even slightly higher than the resonator length of the bar-shaped semiconductor laser, the film thickness near the light emitting region will be reduced to a predetermined thickness. will not reach it. On the other hand, if the semiconductor laser bar 1 is too high than the rectangular parallelepiped jig 2, the film wraps around the electrode portion, worsening the heat dissipation of the semiconductor laser and hindering mounting on a heat sink and wire bonding. Therefore, the rectangular parallelepiped jig 2 is 10 to 20μ smaller than the semiconductor laser bar 1 as shown in FIG.
Those with a low m height are used.

[Problem to be solved by the invention]

When the above-described conventional method for forming an end face protective film is used, the following problems occur. First, the resonator length of a bar-shaped semiconductor laser has a variation of approximately ±10 μm due to variation in the distance between walls. Therefore, as mentioned above, in order to prevent the film from wrapping around to the electrode side as much as possible while ensuring a predetermined film thickness, we prepared several types of rectangular parallelepiped jigs with different heights and adjusted them to fit each semiconductor laser bar. Therefore, it is necessary to select a rectangular parallelepiped jig, which requires time, so conventional jigs have low mass productivity. The second point is that in the conventional method, wrapping around to the electrode side always occurs. In particular, the wrap around the mounting surface for mounting onto a heat sink made of silicon, diamond, etc. must be suppressed as much as possible to ensure sufficient heat dissipation. The present invention provides a method for forming an end face protective film that eliminates these problems.

[Means to solve the problem]

The present invention provides a method for closely arranging and fixing a plurality of semiconductor laser bars in which a plurality of semiconductor lasers each having a multilayer structure including a light-emitting region are connected on a flat support base with the light emitting end face facing upward. The structure is such that an insulating film is deposited on the light emitting end face which is arranged at an angle.

[Example 1] Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. In this example,
The present invention is applied to a semiconductor laser having an upside-down mount structure in which the electrode 6a on the light emitting region side is mounted on a heat sink, which is commonly used to efficiently dissipate heat generated in the light emitting region. When the thickness is 100 μm, the resonator length is about 300 μm, and the variation is ±10 μm,
As shown in the figure, the fixing jigs 3a and 3b have surfaces that contact the semiconductor laser bars with an inclination of about 12°, and between them, the plurality of semiconductor laser bars 1 are attached to the electrodes 6 on the light emitting region 5 side.
Align a to the left side, stack them and sandwich them, and attach the flat support base 4.
Fix to. In this state, a protective film is formed from above on the upper end surface 7a of the semiconductor laser bar by sputtering or the like.

Next, place the lower end surface 7b upward, and in the same manner, the end surface 7b
A protective film is also formed on b.

According to this method, the end face near the light emitting region is lower than the adjacent semiconductor laser bar, but because it is tilted, 5. A protective film having a uniform film thickness and a predetermined thickness can be formed over the entire end face. At the same time, it is possible to almost completely prevent the protective film from wrapping around the mounting surface.

At this time, the electrode 6b on the side opposite to the mounting surface has a wraparound of about 20 μm on average and about 40 μm at the maximum on one side, but this does not interfere with wire bonding.

[Example 2] FIG. 2 is a sectional view showing a second embodiment of the invention.

The present embodiment is applied to a semiconductor laser with an up-side up-mount structure, which is a semiconductor laser with good heat dissipation and is used to avoid distortion caused by the mount on the light emitting region. In this case, the mounting surface is the light emitting area 5
Since the electrode 6b is on the far side, contrary to the first embodiment, the electrode 6b is aligned on the left side, a plurality of semiconductor laser bars 1 are overlapped, and the fixing jigs 3a and 3b are used to support a flat surface. 4 and form a protective film in the same manner as in the first embodiment.

〔Effect of the invention〕

As explained above, the present invention provides a fixing jig with an inclined portion, thereby ensuring the ability to form a predetermined film thickness without the need for a rectangular parallelepiped jig sandwiched between semiconductor laser bars. This has the effect of almost completely preventing wraparound. Therefore, there is no need to select the height of the rectangular parallelepiped jig, which greatly reduces the number of man-hours.In addition, since the rectangular parallelepiped jig is eliminated, the throughput of the protective film formation process is approximately doubled, increasing mass productivity. Are better.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a first embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a second embodiment, FIG. 3 is a vertical cross-sectional view of a conventional protective film forming jig, and FIG. The figure is an external view of a semiconductor laser, No. 5
The figure shows an external view of a semiconductor laser bar. 1... Semiconductor laser bar 2... Rectangular parallelepiped jig, 3
...Fixing jig, 3a, 3b...Fixing jig, 4.
... Planar support base, 5... Light emitting region, 6a... Electrode on the light emitting region side, 6b... Electrode farther from the light emitting region, 7
a. 7b... end surface. Agent Patent Attorney Susumu Uchihara 35 wards 34 reasons 55 problems

Claims (1)

[Claims] A plurality of semiconductor laser bars each having a plurality of semiconductor lasers each having a multilayer structure including a light-emitting region are closely arranged and fixed on a flat support base with the light emitting end face facing up, and the light emitting area arranged at an angle is A method for forming a protective film on a semiconductor laser end face, the method comprising depositing an insulating film on an emitting end face.