JPH07297496A - Method for manufacturing group III nitride semiconductor laser - Google Patents

Abstract

(57) [Abstract] [Purpose] Easily create a mirror surface of a group III nitride semiconductor laser represented by Al _x Ga _Y In _1-XY N (including X = 0, Y = 0, X = Y = 0) To get. [Structure] Zinc oxide (Z
nO) 2 and aluminum nitride (AlN) 8 on other parts
Forming an intermediate layer consisting of a plurality of layers of group III nitride semiconductors (including Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = Y = 0) on the intermediate layer. Forming a semiconductor laser device layer composed of 3, 4, 5;
Only the intermediate layer 2 of zinc oxide (ZnO) is removed by wet etching using a solution that etches only zinc oxide, and the sapphire substrate 1 and the bottom layer 3 of the semiconductor laser device layer are removed.
A method for producing a Group 3 nitride semiconductor laser by forming a gap 20 between the first and second layers, cleaving the semiconductor laser element layer using the gap 20, and making the cleaved surface the mirror surface of the resonator of the laser.

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 a group III nitride semiconductor laser.

[0002]

2. Description of the Related Art A group III nitride semiconductor laser is disclosed in Japanese Patent Laid-Open No. 4-2.
As described in Japanese Patent No. 42985, a p-type technique by electron beam irradiation treatment (including (Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = Y = 0) was used. Things are known.

This semiconductor laser has a sapphire substrate
A buffer layer of 1N is formed, and a hetero-pn junction of a group III nitride semiconductor (including (Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = Y = 0) is formed thereon. It was formed.

[0004]

In this laser, the cleaved surface of the group III nitride semiconductor laser device layer cannot be obtained unless cleaved together with the sapphire substrate. However, it is difficult to cleave the sapphire substrate itself, and the A-axis of the sapphire and the group III nitride semiconductor are deviated by 30 degrees.
There is a problem that a good cleavage surface of the group nitride semiconductor laser device layer cannot be obtained.

According to the present invention, 3 formed on a sapphire substrate is used.
It is to improve the laser output by obtaining a good cleavage surface of the laser element layer made of a group nitride semiconductor.

[0006]

According to the present invention, zinc oxide (ZnO) is formed in a part of a sapphire substrate and an intermediate layer made of aluminum nitride (AlN) is formed in another part of the sapphire substrate.
Group III nitride semiconductor (Al _x Ga _Y In _1-XY N; X =
(0, Y = 0, X = Y = 0 is included), a semiconductor laser device layer including a plurality of layers is formed, and only an intermediate layer of zinc oxide (ZnO) is formed by wet etching using a solution that etches only zinc oxide. To form a gap between the sapphire substrate and the bottom layer of the semiconductor laser device layer, cleave the semiconductor laser device layer using the gap, and make the cleaved surface the mirror surface of the laser cavity. Is a method for manufacturing a group III nitride semiconductor laser.

[0007]

[Operation and effect of the invention] Zinc oxide (ZnO) and AlN
The lattice constants of sapphire and group III nitride semiconductors (Al _x Ga _Y In
_1-XY N; including X = 0, Y = 0, X = Y = 0)
Both materials function as a buffer layer capable of growing a good-quality Group III nitride semiconductor on the sapphire substrate. Then, by removing only the intermediate layer of zinc oxide (ZnO) by etching, a gap can be formed between the sapphire substrate and the group III nitride semiconductor laser device layer in that portion. Then, by utilizing this gap, only the group III nitride semiconductor laser device layer can be cleaved. Therefore, it is possible to obtain an extremely high quality mirror surface that forms the resonator of the laser element. Therefore, the output of the laser element can be greatly improved.

[0008]

EXAMPLES The present invention will be described below based on specific examples. (Al _x Ga _Y In _1-XY N; including X = 0, Y = 0, X = Y = 0) A horizontal organometallic compound vapor phase epitaxy apparatus was used for the production of a single crystal for a semiconductor laser diode. As shown in FIG. 1, (00
A sapphire substrate 1 having a plane orientation of 01) direction was prepared, and the sapphire substrate 1 was washed with an organic chemical such as methanol. Then, the sapphire substrate 1 was set in the chamber of the RF sputtering apparatus, and the chamber was evacuated to vacuum. After that, a ZnO target is sputtered with a mixed gas of argon and oxygen, and the thickness of the ZnO target is uniformly 100 nm on the upper surface of the sapphire substrate 1, as shown in FIG.
Thus, the intermediate layer 2 made of ZnO was formed.

Next, a photoresist is uniformly coated on the ZnO intermediate layer 2 and exposed in a predetermined pattern.
After development, the photoresist was left in the portion where the intermediate layer 2 of ZnO was left. Then, using the photoresist having the predetermined pattern as a mask, the unmasked portion of the intermediate layer 2 of ZnO was removed by etching with aqua regia.

In this way, as shown in FIGS. 3 and 4, the ZnO intermediate layer 2 was formed in a lattice pattern. Next, this sapphire substrate 1 is placed in a crystal growth portion of a crystal growth apparatus after being washed with an organic material. After evacuation of the growth furnace, hydrogen is supplied and the temperature is raised to about 1200 ° C. As a result, the hydrocarbon gas attached to the surface of the sapphire substrate 1 is removed to some extent.

Next, regarding the step of forming a semiconductor laser device layer on the sapphire substrate 1 processed as described above,
This will be described with reference to FIGS. 5, 6 and 7. FIG. 5 shows A of FIG.
6 is a sectional view taken along line A-A, and FIG. 6 is a sectional view taken along line BB in FIG.
That is, the cutting directions of FIGS. 6 and 5 form an angle of 90 degrees.

The temperature of the sapphire substrate 1 is lowered to about 600 ° C., and trimethyl aluminum (TMA) and ammonia are added.
By supplying (NH ₃ ), as shown in FIG. 5, an AlN layer 8 having a uniform film thickness of about 50 nm is formed on the sapphire substrate 1. Next, only the supply of TMA was stopped, the substrate temperature was raised to 1040 ° C, and TMA, trimethylgallium (TMG) and silane (SiH
₄ ) is supplied to grow the Si-doped n-type GaAlN layer 3 (n layer).

Once the wafer is taken out of the growth furnace, GaAl
After masking a part of the surface of the N layer 3 with SiO _2, it is returned to the growth furnace and evacuated to supply hydrogen and NH ₃ to raise the temperature to 1040 ° C. Next, as shown in FIG. 5 and FIG. 7, TMG is supplied to a portion not masked with SiO ₂ to have a thickness of 0.5 μm.
GaN layer 4 is grown. Next, by further supplying TMA and biscyclopentadienylmacnesium (Cp ₂ Mg),
As shown in FIGS. 5 and 7, the doped GaAlN layer 5 (p layer) is
It grows 0.5 μm.

Next, the SiO ₂ used as the mask is removed with a hydrofluoric acid type etchant. Next, as shown in FIGS. 5 and 7, after depositing a SiO ₂ layer 7 on the doped GaAlN layer 5 (p layer), a window 7A is opened in a strip shape having a length of 1 mm and a width of 50 μm.
It is moved to a vacuum chamber and the doped GaAlN layer 5 (p layer) is subjected to electron beam irradiation treatment. The electron beam irradiation treatment conditions were an electron beam acceleration voltage of 15 KV, an emission current of 120 μA or more, an electron beam spot diameter of 60 μmφ, and a sample temperature of 297.
K.

Next, as shown in FIG. 7, the window 7A portion of the doped GaAlN layer 5 (p layer) and the Si-doped n-type GaAlN layer 3 are formed.
Metal electrodes 6A and 6B are formed on the (n layer), respectively.

As described above, the sapphire substrate 1 on which the group III nitride semiconductor laser layer was formed was immersed in a hydrochloric acid-based etchant, and the etchant temperature was set to 60 ° C. Then, only the intermediate layer 2 of ZnO was etched in an ultrasonic cleaner for about 10 minutes. As a result, ZnO shown in FIG.
The intermediate layer 2 is removed, and as shown in FIG. 6, the sapphire substrate 1 and the Si-doped n-type which is the lowermost layer of the semiconductor laser device are removed.
Lattice-shaped gaps 20 were formed between the GaAlN layer 3 (n layer).

Next, as shown by the line C--C in FIG. 4, a sharp blade is pressed from directly above the lattice-shaped gaps 20 from the upper surface of the SiO ₂ layer 7 to form the doped GaAlN layer 5 (p layer). , GaN layer 4,
The semiconductor laser device layer composed of the Si-doped n-type GaAlN layer 3 (n layer) was cleaved. As a result, the cleaved end surface becomes the mirror surface of the laser resonator.

Next, as shown in FIG. 4, the lattice-shaped gaps 2 are formed.
Dicing is performed along 0 to obtain each semiconductor laser chip. In the above embodiment, the thickness of the ZnO intermediate layer 2 is 100 nm, but it can be used in the range of 10 nm to 10 μm. In the above example, the GaN of the active layer is
Layer 4 is doped GaAlN layer 5 (p layer) and Si-doped n-type GaAlN
Since the layer 3 (n layer) is scissors, a semiconductor laser having a pn structure is realized by two heterojunctions. But,
The layer structure of this semiconductor laser device layer may be arbitrary as long as a pn junction is formed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method for manufacturing a semiconductor laser according to a specific embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the method of manufacturing the semiconductor laser according to the embodiment.

FIG. 3 is a cross-sectional view showing the method of manufacturing the semiconductor laser according to the embodiment.

FIG. 4 is a plan view showing the method of manufacturing the light emitting diode according to the embodiment.

5 is a sectional view taken along the line AA in FIG. 4 showing the method for manufacturing the light emitting diode according to the embodiment.

FIG. 6 is a cross-sectional view taken along the line BB in FIG. 5, showing the method for manufacturing the light emitting diode according to the embodiment.

FIG. 7 is a sectional view showing the method for manufacturing the light emitting diode according to the embodiment.

[Explanation of symbols]

1 ... Sapphire substrate 2 ... Intermediate layer of ZnO 3 ... Si-doped n-type GaAlN layer (n layer) 4 ... GaN layer 5 ... Doped GaAlN layer (p layer) 6A, 6B ... Electrode 7 ... SiO ₂ layer 20 ... Gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 591014950 Hiroshi Amano 2-chome Yamanote, Meito-ku, Nagoya, Aichi 104 Takara Condominium Yamanote 508 (72) Inventor Masayoshi Koike, Kasuga Town, Nishiichi Kasugai-gun, Aichi Prefecture Nagahata 1, Nagata Synthetic Co., Ltd. (72) Inventor Norikatsu Koide 1 Ochiai, Nagahata, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Toyota Synthetic Co., Ltd. (72) Inventor Hiroshi Amano Room No. 103, Bldg. 19, Nijigaoka Higashi Danchi, 21-21 Kamioka-cho, Meito-ku, Nagoya, Aichi

Claims (2)

[Claims] 1. Zinc oxide (ZnO) is formed on a part of a sapphire substrate and aluminum nitride (AlN) is formed on another part.
Is formed on the intermediate layer, and a Group III nitride semiconductor (Al _x Ga _Y In _1-XY N; X =
The intermediate layer of zinc oxide (ZnO) is formed by wet etching using a solution that etches only zinc oxide by forming a semiconductor laser device layer composed of a plurality of layers (including 0, Y = 0, X = Y = 0). And removing only this to form a gap between the sapphire substrate and the lowermost layer of the semiconductor laser device layer, cleaving the semiconductor laser device layer using the gap, and cleaving the cleaved surface of the laser resonator. A method for manufacturing a group III nitride semiconductor laser by using a mirror surface of 2. The thickness of the intermediate layer according to claim 1,
It is 0 nm to 10 μm.