JPS5858831B2 - Method for manufacturing semiconductor light emitting device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor light emitting device.

Distributed feedback type laser,
Several types of lasers are being considered, including integrated dual waveguide lasers; Nischitic resonant surface lasers.

Among these, etched resonant surface lasers are very simple to manufacture and have been extensively researched, but continuous oscillation at room temperature has not yet been achieved.

The reasons for this are (1) a structure that could effectively dissipate the heat generated in the active region had not been found, and (2) in the conventional etching method, the cavity surface was not sufficiently flat. There were two main reasons: the oscillation threshold was high.

The present invention relates to a method of manufacturing a semiconductor laser device that eliminates the above-mentioned conventional drawbacks and realizes continuous oscillation at room temperature for the first time as an etched resonant surface type laser.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a perspective view showing a semiconductor laser device manufactured according to an embodiment of the present invention, in which the laser element region as a light emitting part is formed into a mesa stripe shape, and a high resistance Ga layer is formed on the side surface of the laser element region.
In this structure, the heat generated in the active region 2 is absorbed by the p-GaAl
Not only through As3, p+-GaAs4, but also through GaA
It can also escape to the electrode 21 through s1 xpx 11.

Therefore, by attaching the electrode 21 to a heat dissipating body such as a copper block, the heat dissipation characteristics can be greatly improved.

Further, by setting the stripe width to about 1 to 2 μm, the oscillation threshold value can be lowered to about 10 mA, and continuous oscillation at room temperature is possible without attaching a heat sink to the electrode 21.

Cavity surface 3 for laser oscillation as a light emitting surface of the light emitting part
1 is formed by etching, but in order to maximize flatness on any crystal plane, we developed a mixed solution of sodium hydroxide, hydrogen peroxide, and ammonia water.

Conventionally, chemical etching solutions for forming cavities include:
H2SO, H2O2, H2O mixture, or H2O
A mixed solution of 2, NH, and OH was often used, but with these solutions, the light emitting surface 31, which serves as the cavity for resonance, may have many unevenness in some parts, and the difference in etching rate between GaAs and G'aAIAs may occur. Due to the large size, the cavity end face 31 was not flat as shown in FIG. 2a, which caused problems.

For example, if you use a mixture of H2O2, NH, and OH,
The result will be as shown in Figure 2a.

In this case, the end of the active region 2 of the light emitting part is not perpendicular to the bonding surface, and the reflectance decreases, making it impossible to form a good resonant surface.

Also, since the GaAlAs layers 1 and 3 are etched deeper than the active region 2, current is not uniformly injected into the active region 2, thus significantly increasing the oscillation threshold.

When a mixed solution of sodium hydroxide solution, hydrogen peroxide solution and ammonia solution is used as the etching solution, by appropriately selecting the amounts of each solution, as shown in Fig. 2,
The cavity end face is perpendicular to the bonding surface, and its etched surfaces can also be aligned in the same plane.

This was true for any crystal plane.

As a result of the experiment, sodium hydroxide made into a 1 molar aqueous solution,
3-10 30% hydrogen peroxide solution and 30% ammonia solution:
When etched with an etching solution prepared at a ratio of 1:1, the cavity end face was the flattest and the oscillation threshold was also low.

A method for manufacturing a semiconductor laser device will be described in detail below with reference to specific examples.

Note that FIGS. 3 a to 3 e and 3 a' to e' are process cross-sectional views and plan views of the method for manufacturing a semiconductor laser device of the present invention,
FIG. 4 is a completed perspective view of the same.

Example substrate (IX 1018cIfr3f) n-type Ga
A (100) plane of As5 was used, and an n-GaAlAs layer 1. p-Ga
As layer z, p GaAlAs layer 3. A p+-GaAs layer 4 is grown (Fig. 3a, a).

Next, a SiO2 film 6 is deposited on the surface of the p+-GaAs layer 4, and a 5in2 film 6 is left in a stripe shape of 3 μm width using a photoetching technique, and the other SiO□ film is removed.

The stripe direction may be any direction, but in this experiment it was set to (1
00), (110).

(120) stripes were made in three directions (same as above).

b/).

Next, the area to which the SiO2 film 6 is not attached is etched using a mixture of sulfuric acid, hydrogen peroxide, and aqueous ammonia.

The etching depth is 2 to 3 μm.

At this time, GaAs and GaAlA directly under the stripe part
S is also etched, and the stripe width becomes about 1 μm (e and C in the same figure).

Next, photoetching is performed again so that the SiO2 film 6 remains only on the upper part of the stripe part, and the SiO2 film 6 is grown in a region other than the stripe part by a single-phase growth method on one high-resistance GaAs□-XPX layer.

In this example, Ga AS, 99''0.01 was grown by a pyrolysis method using Ga (CHa) ss AsH2 and PH3.

At a growth temperature of 630° C., a buried layer with a specific resistance of 1040 − was formed.

At this time, the surface of the buried layer and the surface of p-GaAs4 are made to be on the same plane (d and d' in the same figure).

Next, after removing the SiO2 film 6 with hydrofluoric acid, the entire surface is
A u-Zn alloy 21 is deposited by vapor deposition and etched by 300 mm in a direction just perpendicular to the stripe direction using a photoetching method.
Leaving the Au-Zn alloy 21 with a μm width, the other Au-Zn is removed (e and e in the same figure).

Next, 1 mol sodium hydroxide = 30-rich hydrogen peroxide solution: 3
Au
- GaAs and GaAlAs in the areas to which the Zn alloy 21 is not attached are removed by etching.

The etching depth at this time is approximately 5 μm.

The end face of the cavity after this etching can be fully utilized as a laser resonator, as described above.

After that, the total thickness will be 100 μm.
A monolithic laser device as shown in FIG. 4 is completed by polishing s5, attaching electrode metal 22, and cutting to an appropriate size including a stripe region.

In the photoetching process of Au-Zn alloy 21, Au-Z
If the n-alloy 21 is left in a suitable shape, a laser having the structure as shown in FIG. 2 can be easily produced.

It goes without saying that the present invention can be used not only for semiconductor laser devices but also for semiconductor light emitting devices such as ordinary light emitting diode devices.

Furthermore, the etching solution of the present invention includes Ga, Al*As5P.
Naturally, it can be used as an etching solution for manufacturing various semiconductor devices other than semiconductors containing .

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a semiconductor laser device manufactured according to an embodiment of the present invention, FIGS. 2a and 2b are comparison views of the conventional and inventive cross-sections of the cavity end of the laser device, and FIG. 3 is a. −
e and a'-♂ are a process sectional view and a plan view showing one embodiment of the method for manufacturing a semiconductor light emitting device of the present invention, and FIG. 4 is a structural perspective view of a semiconductor laser device obtained by the embodiment. 1-------n-GaAIAs, 2...---p-
GaAS. 3--p-GaAIAs, 4--p+-GaAs
15 ・----n-Ga As, 5-------
8 i 02 film, 11-... High resistance Ga A
s I z P z layer, 21, 22------
Open electrode, 31... Resonance surface by etching.

Claims (1)

[Claims] 1. When forming a mesa stripe-shaped light-emitting part made of GaAs and GaAlAs and including an active region on a semiconductor substrate, the light-emitting surface perpendicular to the bonding surface of the light-emitting part is treated with an aqueous solution of sodium hydroxide and hydrogen peroxide. A method for manufacturing a semiconductor light emitting device, characterized in that etching is performed using a mixed solution of water and aqueous ammonia.