JPH04113685A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a threshold current and to obtain a high efficiency by selectively etching a-substrate with a stripe mask formed thereon as a mask, forming a mesa stripe thereon, and sequentially forming a reverse conductivity type first semiconductor layer, a-conductivity type second semiconductor layer, a third semiconductor layer and further a fifth semiconductor layer having wider forbidden band width than that of the fourth semiconductor layer. CONSTITUTION:A stripe mask 11 is fanned on a p-type GaAs substrate 10, and chemically etched with the mask 11 as a mask to form a mesa stripe 10a. Then, the mask 11 is removed with fluoric acid, then a GaInP layer, i.e., a third semiconductor layer 14 is removed with hydrochloric acid, and the surface of a p-type GaAs layer 13 is protected against contamination. In a later step, the surface is secondly grown. In this case, since the layer 13 is formed to previously form a p-n reverse junction boundary together with an n-type GaAs layer 12 of the base, no defect is generated in the boundary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor light emitting device, particularly a 0°6 μm band visible light semiconductor laser device.

The above-mentioned 0.6 μm band visible light semiconductor laser device is expected to be a device that realizes higher performance of optical information processing devices such as optical disk devices and laser printers because the writing density is inversely proportional to the square of the wavelength. Semiconductor laser devices for these applications must have low threshold current and high efficiency to reduce power consumption, and must have low astigmatism characteristics to improve writing and reading characteristics. is necessary.

[Conventional technology]

In order to meet the above requirements, conventional structures that increase the difference in refractive index in the lateral direction have been created by forming mesa stripes on a substrate and growing crystals on this substrate using metal organic vapor phase epitaxy (MOVPE). A semiconductor laser device has been proposed in which an active layer is formed and a light emitting region is formed at the tip of a step.

FIG. 2 shows a manufacturing process diagram of the conventional semiconductor laser device. In the same figure (A), a stripe mask 2 of silicon oxide or the like is formed on a p-type GaAs (gallium arsenide) substrate 1, and mesa stripes 1a are formed by etching using this as a mask.

Next, in FIG. 1B, n-type GaAs layers 3 for current confinement are formed on both sides of the mesa stripe 1a by MOVPE, and the stripe mask 2 is removed. Next, the same figure (
As shown in C), p-type AlGa is deposited on the surface using the MOVPE method.
InP (aluminum gallium indium phosphide) layer 4. Ga1nP (gallium indium phosphide) layer5. n-type AlGa InP layer6. n-type GaAs layer 7
grow.

[Invention or problem to be solved]

In the above conventional method, the surface of the n-type GaAs layer 3 shown in FIG. 2(B) is contaminated during the cooling process after the growth, and when the p-type AIGaInP layer 4 shown in FIG. 2(C) is grown on this surface. When a defect occurs on the surface of the n-type GaAs layer 3 and the device is operated as a semiconductor laser device, the n-type GaAs layer 3 for current confinement becomes p-type AlGaInPn.
There were problems in that leakage current occurred at the reverse junction interface of the seed layer, increasing the threshold current and decreasing efficiency.

The present invention provides a method for manufacturing a semiconductor device that can reduce leakage current at the reverse junction interface between a semiconductor layer for current confinement and a semiconductor layer on the surface thereof, reduce threshold current, and obtain high efficiency. The purpose is to

[Means to solve the problem]

The above problem is solved by the process of selectively etching a newly created stripe mask on a semiconductor substrate of one conductivity type to form a mesa stripe on the substrate, and the process of forming a mesa stripe on a semiconductor substrate of the opposite conductivity type using the mesa stripe as a mask. a step of selectively forming a semiconductor layer, a second semiconductor layer of one conductivity type, and a third semiconductor layer in order from the surface of the semiconductor substrate; and a step of removing the stripe mask and the third semiconductor layer. , a fourth semiconductor layer on a substrate including mesa stripes;
The present invention is solved by a method for manufacturing a semiconductor device, which includes a step of sequentially forming a fifth semiconductor layer having a wider forbidden band width than that of the semiconductor layer.

[Effect]

In the present invention, the first to third semiconductor layers are stacked on both sides of a mesa stripe in the first growth, and after the third semiconductor layer is removed, the fourth semiconductor layer is deposited in the second growth. A fifth semiconductor layer is laminated. The third semiconductor layer can protect the surface of the second semiconductor layer from contamination when the temperature drops, and by forming the second semiconductor layer, a reverse junction interface is created in advance with the underlying first semiconductor layer. Therefore, the second growth will not cause defects at this reverse junction interface.

Therefore, the first. The leakage current at the reverse junction interface for current confinement created by the second semiconductor layer can be reduced, the threshold current can be reduced, and high efficiency can be obtained.

〔Example〕

FIG. 1 shows a manufacturing process diagram of an embodiment of the present invention.

In the same figure (A), p-type GaAs with plane orientation (100)
A stripe mask 11 is formed on the substrate 10, and using this mask as a mask, chemical etching is performed using a mixed solution of sulfuric acid and hydrogen peroxide to form mesa stripes 10a. Next, using the MOVPE method at a growth temperature of 690°C, SiH,
n-type GaA with (monosilane) dopant, TEG ()ethylgallium), AsH, (arsine) source gas
An s-layer (first semiconductor layer) 12 is formed to a thickness of 0.8 μm, and p-type GaA is coated on its surface with a dopant of DMZ (dimethylzinc), a source gas of TEG, and AsH2.
An S layer (second semiconductor layer) 13 is formed to a thickness of 0.2 μm, and Ga I is further formed on its surface using raw material gases such as TEG, TMI (l-lymethylindium), PH, and (phosphine).
The nP layer 14 is formed to a thickness of 0.2 μm. The first growth is completed through each of the above steps, and the temperature is lowered.

Next, the stripe mask 11 is removed with hydrofluoric acid, and then the Ga1nP layer (third semiconductor layer) 14 is removed with hydrochloric acid to obtain the shape shown in FIG. In this case, the surface of the GalnP layer 14 will be contaminated when the temperature is lowered, or this will be removed, so there is no problem.
3 surfaces can be protected from contamination. Also, whether a second growth is performed on the surface of the lever in a later step or the p-type GaAs layer 1
3, the underlying n-type GaAs layer 1
Since a p-n reverse junction interface is created in advance with 2, defects will not occur at this reverse junction interface, but defects will occur at the reverse junction interface between the n-type GaAs layer 3 and the p-type AlGa1nP layer 4. Compared to the conventional example shown in FIG. 2, the leakage current at this reverse junction interface can be reduced, the threshold current can be reduced, and a highly efficient semiconductor laser device can be obtained.

Next, in FIG. 1(C), the DMZ dopant, PH, T
EG, TMI, TMA (trimethylaluminum) raw material gas p-type A] Ga1nP layer (fifth semiconductor layer) 1
5, and a GalnP layer (fourth semiconductor layer) 16 is formed on the surface using raw material gases of TEG, TMT, and PH,
Furthermore, SiH4 dopant, TEG, TM
I.

An n-type AlGaTnP layer (fifth semiconductor layer) 17 is formed using a TMA source gas, and an n-type GaAsJii 18 is further formed on its surface using a SiH4 dopant and TEG, As Hs source gases. In this case, p-type A]G
aInP layer 15. The n-type AlGa InP layer 17 is Gal
It is necessary that the forbidden band width be wider than that of the nP layer 16.

Next, Au-Zn (gold/zinc) is applied to the p-type GaAs substrate 10.
A layer 19 and an Au layer 20 are evaporated to form a p-electrode, and an n-type Ga
Au-Ge (gold/kermanium) layer 21 on As layer 18
is vapor-deposited to form an n-electrode, and the resonator is separated at a cavity length of 300 μm to complete the process.

Note that the n-type GaAs layer 12 may be an n-type A]GaAs layer, and the conditions of the first semiconductor layer are A1. -, Ga, As (
0<x≦1). Further, the Ga InP layer 14 is made of AlG
It may be an alnP layer, and the conditions for the third semiconductor layer are (A I
+-8Ga, ) o, s I no, s P(0
(X≦1). Further, the GalnP layer 16 is made of AlGa
It may be an InP layer, and the conditions for the fourth semiconductor layer are (A I
+-y Gay) o, s I no, s P (
0<'1≦1). Also, p-type AlGa InP layer 1
5 and p-type AlGa InPIiil 7 (fifth semiconductor layer) conditions are (A I I-z Ga-) o, s
I no, s P O'<z<1).

〔Effect of the invention〕

As explained above, according to the present invention, the first growth is performed on both sides of the mesa stripe in the first growth. After laminating a 2nd third semiconductor layer and removing the third semiconductor layer, a 4th layer is grown on the mesa stripe and on the stacked structure of the first growth. Since the fifth semiconductor layer is laminated, the first. The reverse junction interface for current confinement created by the second semiconductor layer will not be contaminated and cause defects, thereby reducing leakage current at the reverse junction interface, reducing threshold current, and achieving high efficiency. I can do it.

[Brief explanation of drawings]

FIG. 1 is a manufacturing process diagram of an embodiment of the present invention, and FIG. 2 is a manufacturing process diagram of a conventional example. In the figure, 10 is a p-type GaAs substrate (semiconductor substrate), 10a is a mesa stripe, 11 is a stripe mask, 12 is an n-type GaAs layer (first semiconductor layer), and 13 is a p-type GaAs layer (second semiconductor layer). ), 4 is a Ga InP layer (
5 is a p-type AlGa InP layer (fifth semiconductor layer), 5 is a p-type AlGa InP layer (fifth
semiconductor layer) 6 is a Ga InP layer (fourth semiconductor layer),
7 is an n-type AlGa InP layer (fifth semiconductor layer) 8 is an n-type AlGa InP layer (fifth semiconductor layer)
Figure 3 shows a shaped GaAs layer.

Claims (1)

[Claims] A step of selectively etching using a stripe mask (11) formed on a semiconductor substrate (10) of one conductivity type as a mask to form a mesa stripe (10a) on the substrate (10). Using the stripe mask (11) as a mask, a first semiconductor layer (12) of opposite conductivity type, a second semiconductor layer (13) of one conductivity type, and a third semiconductor layer (14) are formed. selectively forming the stripe mask (11) and the third semiconductor layer (10) in order from the surface of the semiconductor substrate (10);
4), and a fourth semiconductor layer (16), a fourth semiconductor layer (16) having a wider forbidden band width than the fourth semiconductor layer (16), is formed on the substrate (10) including the mesa stripe (10a). 5 semiconductor layers (1
5 and 17).