JPH02215176A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To protect a wafer against breakdown so as to handle it easily by a method wherein an electrically isolating groove is provided to a wafer through etching and electrodes are formed through evaporation before polish, and then the semiconductor wafer in which many semiconductor lasers are built is polished to be as thick as specified. CONSTITUTION:A wafer 10' is coated with an SiNx film 21 through a plasma CVD method before electrodes are provided to the wafer 10', a resist film 22 is provided thereon, and a resist pattern 22A is formed through photolithography. Next, the film 21 is patterned with a buffer hydrofluoric acid using the pattern 22A as a mask to leave only a pattern 21A unremoved. A groove 23 is formed on an exposed face of the wafer 10' through etching with bromomethanol or the like using the pattern 21A as a mask. Then, the pattern 21A is removed, the wafer 10' is polished to be as thick as specified, both the sides of the wafer 10' are coated with electrode material 24 such as AuGeNi, AuZn or the like, the material 24 is separately provided inside the groove 23 formed on the upside of the wafer 10', and a negative electrode 7 and a positive electrode 8 are formed on the upside and the underside of the wafer 10' respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor laser used as a light emitting source for optoelectronic devices, particularly an optical communication device and an optical meter 111m.

[Conventional technology]

FIG. 4 shows the state of a semiconductor laser wafer.

A large number of semiconductor lasers are formed on the wafer.
The second wafer 10 is cleaved into strip-shaped arrays 13. Then, this cleavage plane 12 becomes a light emitting hole.

As a method for testing the characteristics of a semiconductor laser, if the wafer 10 is separated into individual semiconductor lasers, handling becomes difficult because the semiconductor lasers are small (approximately 300 μm square). Therefore, the array 13 in the form of a rectangle is easily measured and handled as it is.

In order to measure the characteristics of each semiconductor laser in the state of the array 13, it is necessary to electrically isolate the semiconductor lasers. A groove 11 is provided in a direction perpendicular to the cleavage plane 12 to electrically isolate the semiconductor lasers.

FIG. 5 is a perspective view showing an example of a conventional array state.

In this figure, 1 is a p-1n P substrate, 2 is a p-1
nP buffer layer, 3 is p-InGaAs active layer, 4 is n
-InP cladding layer, 5 is an n-In pH flow blocking layer, 6 is a p-InP current blocking layer, 7 is a negative electrode, 8 is a positive electrode, and 11 is a groove.

Such a structure has p-In on the p-1n P substrate 1.
Pba'11'77 layer 2. p-1nPGaAsP active layer 3
．． After forming the n-InP cladding layer 4 by sequential epitaxial growth, a mesa structure is formed, and further n-InP cladding layer 4 is formed by epitaxial growth.
P current blocking layer5. After epitaxially growing the p-InP current blocking layer 6, a negative electrode 7, a positive electrode 8. The groove 11 is formed therein.

Next, the conventional method of forming this groove 11 will be explained in FIGS. 6(a) to (h).
).

First, the wafer 10', which has a thickness of about 400 μm before forming the electrodes 7 and 8, is polished to about 100 μm, and as shown in FIG. A pattern 14 is formed. Next, Figure 6 (b
), using the resist pattern 14 as a mask, a metal film 15 such as AuZn or AuGeNi is deposited on the bifacial surface, and then the unnecessary metal film is removed by lift-off as shown in FIG. 6(C). 15 and resist pattern 14
remove.

Next, as shown in FIG. 6(d), the entire wafer 10' is heated.
and the metal film 15 are alloyed. After that, the 10th (
A resist pattern 16 is formed by a photolithography process as shown in e), then a metal M17 such as Au is formed on the entire surface by vapor deposition as shown in FIG. 6(f), and then a resist pattern 16 is formed by lift-off as shown in FIG. The resist pattern 16 is removed and etching is performed using the metal film 17 as a mask to form the groove 11 as shown in FIG. 6(h).

[Problem to be solved by the invention]

In the conventional groove forming method described above for electrically isolating the semiconductor lasers, the wafer 10' is polished before forming the groove 11, and when the wafer 10' has a thickness of about 100 μm, the first groove is formed.・Due to the lithography process, etc., it was easily broken and had to be handled with great care.

This invention allows for easy handling of wafers and fewer steps.
The present invention provides a method for manufacturing a semiconductor laser, which involves a method for forming a groove for electrically isolating semiconductor lasers.

[Means to solve the problem]

The method for manufacturing a semiconductor laser according to the present invention includes forming grooves for electrical isolation between the semiconductor lasers by etching, then polishing, and then vapor-depositing metal on the entire surface of the wafer 1 to form electrodes separated by the grooves. It forms the

[Effect]

According to this invention, the process of forming etching grooves for electrically isolating semiconductor lasers is greatly facilitated.

〔Example〕

FIGS. 1(a) to 1(g) are process diagrams for explaining one embodiment of the present invention. First, as shown in FIG. 1(a), Si is deposited on the wafer 10' before electrode formation using the plasma CVD method.
An Nx film 21 is formed. Next, a resist film 22 is formed on this 5iNxl 121, and then a resist pattern 22A is formed in a photolithography process (see FIG. 1).
b)) Using this resist pattern 22A as a mask, the SiNx film 21 is patterned using buffered hydrofluoric acid, etc.
An Nx film pattern 21A is formed [FIG. 1(C)]. Next, using the SiNx film pattern 21A as a mask, etching is performed with bromethanol or the like to form a groove 23, and then the entire SiNx film pattern 21A is removed [FIG. 1(d)].
), the wafer 10' is polished to about 100 μm. Next, AuGeNi or A
An electrode material 24 such as uZn is deposited [FIG. 1(e)], heated and alloyed [FIG. 1(f)], and Au'IF is deposited on top of it.
7. Deposit II material to form negative electrode. Forming the positive electrode 8 [first
Figure (g)).

According to the above manufacturing method, the groove 23 has a dovetail shape, and the width of the groove widens from the surface to the inside of the groove. This widened part becomes a shadow during vapor deposition, and no electrode metal is vapor-deposited. Semiconductor lasers can be electrically isolated. Therefore, even in the array state, the same current-voltage characteristics as in the case of physically separating the semiconductor lasers into individual semiconductor lasers can be obtained.

FIG. 2 is a current (mA)-voltage (V) characteristic diagram of a semiconductor laser, which is measured in an array in the present invention. On the other hand, the results were exactly the same when the semiconductor lasers were physically separated and measured.

Figure 3 is a current (lrIA) vs. optical output (mW) characteristic diagram, showing two cases in which the Ueno fabricated according to the present invention was measured in an array and one in which it was measured physically separated into individual semiconductor lasers. It showed exactly the same characteristics as the measured case.

From the results shown in FIGS. 2 and 3 above, it was confirmed that the semiconductor lasers in the array state were electrically isolated by the manufacturing method of the present invention.

In the above embodiment, the groove 23 has a dovetail shape, but the present invention is not limited to this shape, and any shape may be used as long as the groove 23 is not deposited on a portion of the groove 23. It is also possible to prevent the wafer 10' from being deposited on a portion of the groove 23 by tilting the wafer 10' during the deposition.

〔Effect of the invention〕

As explained above, in this invention, grooves for electrical isolation are formed in advance by etching before polishing the wafer 1iFF, and then electrodes are formed by vapor deposition. Therefore, the electrodes are separated by the grooves, and the insulation between the semiconductor lasers is improved. It is maintained. Since the wafer is thick during the groove manufacturing process before polishing, it has the advantage of being easy to handle.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a semiconductor laser at each step in an embodiment of the present invention, and FIGS. 2 and 3 are current-voltage characteristic diagrams and current-light output of the semiconductor laser for detailed explanation of the present invention. Characteristic diagram, Part 4 is a perspective view of a conventional wafer on which a large number of semiconductor lasers are formed, Figure 5 is a perspective view showing an example of a conventional semiconductor laser in an array state, and Figure 6 is electrical isolation of a conventional wafer. 3 is a schematic cross-sectional view of a semiconductor laser in each step showing a method for forming a groove for use in the semiconductor laser; FIG. In the figure, 1 is a p-I n P substrate, 2 is a p-I n P substrate, and 2 is a p-I n P substrate.
P rose 1" layer, 3 is p -1n Ga A s P
Active layer, 4 is n −1n P cladding layer, 5 is n −1
nP current blocking layer, 6 p-InPt4 flow blocking layer, 7 negative electrode, 8 positive electrode, 10' wafer, 11 groove, 21
A is a 5iNxllllj pattern, 22A is a resist pattern, 23 is a groove, and 24 is an electrode material. Figure 1 Figure 2 □ Current (mA) Figure 3 Flow through □ (mA) Figure Figure Figure

Claims (1)

[Claims] In a semiconductor wafer on which a large number of semiconductor lasers have been fabricated, grooves are formed in the semiconductor lasers by etching before forming electrodes, and then the wafer is polished to a predetermined thickness, metal is vapor-deposited over the entire surface of the wafer, and the grooves are etched into the semiconductor lasers. 1. A method of manufacturing a semiconductor laser, comprising forming electrodes that electrically separate semiconductor lasers.