JPS6194389A - Manufacture of semiconductor laser element - Google Patents

Abstract

PURPOSE:To obtain structure for constricting currents through one-time epitaxial growth by selectively forming an active layer and a clad layer onto an exposed substrate between striped insulating films shaped onto the semiconductor substrate in an epitaxial manner. CONSTITUTION:Striped insulating films 10 are formed onto an N-InP substrate 1, and a substrate exposed section 11 is shaped in the width of an active layer for a semiconductor laser. Active-layer InGaAsP 12 is liquid-phase epitaxial- formed selectively onto the section 11, and clad-layer P-InP 13 is liquid-phase epitaxial-shaped selectively. P-InP does not grow on the insulating films 10 at that time, but P-InP 13 also grows in the lateral direction because the supersaturation section of a solute in a solution on the insulating film concentrates onto the exposed substrate. A cavity 14 is shaped between the laterally growing P-InP 13 and the insulating film 10 or both InP and the insulating film are brought into contact. Consequently, the P-InP layer 13 is stabilized and stress to the active layer 12 is prevented by coating the surface with an insulating film 15. An opening is bored to the insulating film 15, and electrodes 16, 17 are attached, thus completing an element. According to the constitution, the element can be formed through one-time epitaxial growth and a simple process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a semiconductor laser suitable for optical integrated circuits and the like.

Structure of a conventional example and its problems FIG. 1 shows an example of a buried structure as one of the conventional semiconductor laser elements. First, as shown in Figure 1(a), n-type I
On an nP substrate 1, an n-type InP layer 2 serving as a buffer 1, an InGaAsP layer 3 serving as an active layer, and a P-type InP layer 4 serving as a cladding layer are epitaxially grown in sequence. Next, the first
After etching as shown in Figure 2(b), P-type InP 5 and n-type I are etched as shown in Figure 2(C).
Electrodes 7 and 8 are formed by epitaxially growing nP 6. However, this structure requires epitaxial growth twice, and has drawbacks such as introduction of defects at the interface during embedding and poor etching controllability.

FIG. 2 shows an example of a device in which these processes are simplified. First, as shown in FIG. 2 (?L), on an n-type InP substrate 1, an n-type InP layer 2, an InGaAsP layer 3,
P-type InP layers 4 are epitaxially grown in sequence. Next, as shown in FIG. 2(b), etching is performed, and then, as shown in FIG. 2(C), only the active layer 3 is selectively etched in the lateral direction until the active layer width is sufficient. . Thereafter, in FIG. 2(d), the temperature is raised again and a manoshroom type semiconductor laser device is formed using a mass transformer. In FIG. 2(6), an insulating film 9 is formed to reinforce both sides of the active layer to form a semiconductor laser element. If this structure is used, the epitaxial group 417) step can be performed only once. However, there is a drawback in the ability to control the etching of the active layer in the lateral direction, as shown in FIG. 2(C), and in FIG. 2(d), there is an inconvenience that a heating process is required instead of buried epitaxial growth. It's something you say.

OBJECTS OF THE INVENTION The object of the present invention is to easily obtain a structure for current narrowing of a semiconductor laser device.

Structure of the Invention The present invention selectively forms an active layer on an exposed substrate between striped insulating films formed on a semiconductor substrate.

By epitaxially growing the semiconductor layer that becomes the cladding layer, it is possible to form a current constriction structure in one epitaxial growth.

DESCRIPTION OF EMBODIMENTS The present invention will be described in detail with reference to the drawings, taking an InP semiconductor laser as an example. First, as shown in FIG. 3(a), n
A striped insulating film 10 is formed on an InP type substrate 1. At this time, the exposed substrate portion 11 is made to have a width suitable for the width of the active layer of the semiconductor laser. Next, the exposed part 1 of the board
1, as shown in FIG. 3(b), an In
The eaAs P layer 12 is selectively formed by liquid phase epitaxial growth. Furthermore, a P-type rnP layer 13 which becomes a cladding layer is selectively grown on the active layer 12 by liquid phase epitaxial growth.

In liquid phase epitaxial growth, the P-type InP 13 does not grow on the insulating film 10, but in this case, the supersaturation of the solute in the solution on the insulating film concentrates on the exposed substrate. ), it is possible to grow laterally.

However, in this case, the space between the laterally grown P-type 1nP 13 and the insulating film is a cavity 14 or only a contact, and there is no crystal bond at all. Therefore, P-type InP layer 1
In order to stabilize the active layer 12 and prevent stress on the active layer 12, an insulating film 15 is formed and held as shown in FIG. As shown in Figure (e), electrodes 16 and 17 are formed to constitute a semiconductor laser element.

Effects of the Invention As described above, the present invention provides a structure for current constriction of a semiconductor laser device by selective liquid phase epitaxial growth using a striped insulating film. Therefore, according to the present invention, it is possible to form an element structure with one epitaxial growth and a simple process, which is extremely advantageous for simplifying the element manufacturing process, improving the epitaxial interface state, and integrating on the same substrate. .

[Brief explanation of the drawing]

Figures 1 (&) to (0) and Figures 2 (a) to (e) are process cross-sectional views showing a conventional semiconductor laser device and its manufacturing method, and Figures 3 (2L) to (6) are from this book. 1A and 1B are process cross-sectional views showing a method for manufacturing a semiconductor laser device according to an embodiment of the invention. 1... N-type InP substrate, 1o... Self-insulating film, 11... Striped window, 12...
Active f@ (InGaAsP), 13... Cladding layer (P-type InP). Figure 1 (L) (Tano Figure 2 (O-n Figure 3)

Claims (1)

[Claims] forming a stripe-shaped window suitable for the width of the active layer of the semiconductor laser element on the semiconductor substrate using an insulating film;
A step of selectively forming a semiconductor layer that will become an active layer on the exposed substrate between the insulating films by an epitaxial method, and a step of selectively forming a semiconductor layer that will become a cladding layer on the active layer by an epitaxial method so that the width of the active layer is smaller than that of the active layer. 1. A method for manufacturing a semiconductor laser device, comprising the step of forming the device so as to obtain sufficient lateral growth.