JPS5929486A - Manufacture of semiconductor laser element - Google Patents

Abstract

PURPOSE:To enable a thick electrode layer connecting to the golden ribbon lead to be formed easily by means of a plating process by a method wherein an insulating film is selectively formed on the entire surface of a substrate selectively coated with the insulating film and the backside thereof coated with a gold layer evaporating film to plate the insulating film with a gold layer film excluding the top surface of a mesastriping light emitting region. CONSTITUTION:Several striping grooves 5 with the depth reaching a buffer layer 2 are provided in parallel at specified interval and golden electrode layers 8, 9 are respectively coated to be formed on the surface and back side of a substrate 1 including a selectively formed insulating film 7 excluding the top surface of the divided mesastriping light emitting regions 6 while an oxide insulating film made of SiO2 is patterned selectively coating the specified element separating region to be the boundary between each laser elements to form an insulating film pattern 31 on the electrode layer 9. Several laser elements may be easily formed by means of forming a gold plate layer 32 around several score mum thick with a plating process on the electrode layer 9 and utilizing the insulating film pattern region 31 not gold plated for cleaving each edge parts 33, 34 and 35.

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to an improvement in a method for manufacturing a semiconductor laser device.In particular, it relates to an improvement in a method for manufacturing a semiconductor laser device. The present invention relates to a method for forming a metal electrode layer.

(b) Prior art and problems In general, semiconductor laser elements that emit infrared rays, such as lead-sulfur-selenium (PBSE) or lead-tin tellurocogen, are
As shown in the figure, for example, on a substrate l made of PbTe of p conductivity type, a buffer layer 2 made of P'Ll 'I' e of p2# conductivity type, an active layer 8 made of PbSnTe of p conductivity type, and an active layer 8 made of PbSnTe of p conductivity type are formed. A top layer 4 made of type PI) Te is sequentially deposited by liquid phase epitaxial growth.

Next, on the surface of the substrate 1, a plurality of nutripe-shaped grooves 5 having a depth reaching the buffer layer 2 are provided in parallel at a predetermined interval to form a mesa stripe-shaped light emitting region 6, and further, on the surface of the substrate 1, a light emitting region 5 is formed. An insulating film 7 is selectively formed except for the top surface of the region 6. Then, an electrode layer 8 made of gold (Au) is deposited on the front surface of the substrate 1 including the insulating film 7, and a two-layer electrode layer 9 made of gold and platinum (Au-Pt) is deposited on the back surface. After that, a diamond needle or a safety razor with a sharp tip is applied in a direction perpendicular to the surface of the edge portion of the substrate l corresponding to the predetermined cleavage lines 10 and 11 to press and cleave it. A plurality of semiconductor laser devices shown in the figure are obtained.The semiconductor laser device thus constructed is connected to a top layer 4 on a heat sink base 12 made of, for example, copper and having high thermal conductivity, as shown in the figure. Indium (In
), and the structure is such that the heat generated during operation is dissipated at the PN junction of the element, and the laser beam is continuously oscillated in an excellent manner. Further, a gold (Au) ribbon lead 13 is connected to the other electrode layer 9 of the element using indium (In) as a bonding material.

By the way, in the semiconductor laser device having the above-mentioned configuration,
The reason why the electrode layer 9 provided on the p-conductivity type PI)Te semiconductor region l side has a two-layer structure made of Au-Pt is as follows.
When the electrode layer 9 is composed of only a gold (Au) vapor-deposited layer, the In solder interposed when connecting the gold ribbon lead 13 on the gold vapor-deposited layer and the gold vapor-deposited layer become alloyed, and over a long period of time In order to eliminate the harmful inconvenience in the electrode structure in which the alloyed metal contacts with the p-conductivity type PbTe semiconductor region and acts as a donor, increasing the connection resistance with the gold ribbon lead 13, A Pt layer is stacked on the gold vapor deposited layer to prevent alloying of Au and In. However, when the above-mentioned alloying is suppressed by the Pt layer, the adhesive strength between the wL electrode layer and the gold ribbon lead 13 bonded through the In solder decreases, and the gold ribbon lead 18 becomes It had the disadvantage of being easy to peel off. In order to eliminate this drawback, an attempt has been made to construct the electrode layer 9 with a thick (about several tens of micrometers) gold plating layer using a plating method. A difficult inconvenience has arisen. Therefore, a photoresist film is selectively formed on the electrode layer 9 and the electrode layer 9 in the element isolation region is removed by etching, or
A photoresist film is selectively formed in advance on the element isolation region on the surface of the P'l)T e semiconductor substrate 1 where the electrode layer 9 is to be formed, and then a gold electrode layer is deposited thickly, and then the resist film is removed. However, in the former case, selective etching is not easy because the gold plating layer is thick, and in the latter case, the thick gold plating layer is surrounded by a thick gold plating layer on the resin film. However, there was a drawback that it was difficult to completely remove the resist film.

(c) Purpose of the Invention The present invention has been made in view of the drawbacks of the conventional art described in 1. It is possible to easily form a thick electrode layer to which a gold ribbon lead is to be connected by a plating method without interfering with element separation by cleavage. The object of the present invention is to provide a novel method for manufacturing a semiconductor laser device.

((1) Structure and object of the invention According to the present invention, a plurality of mesa stripe-shaped light emitting regions are provided in parallel to each other on the surface of a compound semiconductor substrate, and a plurality of mesa stripe-shaped light emitting regions are provided on the surface of the substrate other than the top surface of each of the light emitting regions. After selectively depositing an insulating film and then depositing a metal vapor deposited film on the entire surface of the board and the back surface of the substrate, the metal vapor deposited film on the back surface of the substrate is formed between each laser element. a step of selectively forming an insulating film in an element isolation region that is a boundary of the insulating film; a step of plating a metal layer on the metal vapor deposited film except on the insulating film; and cleaving the insulating film portion into a plurality of metal layers. This is achieved by providing a method for manufacturing a semiconductor laser device, which comprises the step of dividing the semiconductor laser device into two semiconductor laser devices.

(e) Embodiments of the invention Embodiments of the invention will be described in detail below with reference to the drawings.

3 to 6 are perspective views showing one embodiment of the method for manufacturing a semiconductor laser device according to the present invention in the order of steps. In each figure below, parts equivalent to those in FIGS. 1 and 2 are given the same reference numerals. As shown in Figure 3, PbT of p4 type
P conductivity type pb' is placed on the e-wiping plate l by a normal manufacturing method.
A buffer layer 2 made of RE, an active layer 8 made of Pb5nTe of p conductivity type, and a top layer 4 made of PbTe of n conductivity type are formed in this order. Thereafter, a plurality of stripe-like grooves 5 having a depth reaching the buffer layer 2 are provided in the surface of the substrate 1 in parallel at predetermined intervals to define a mesanutraipe light emitting region 6, and further, a mesanutraipe light emitting region 6 is formed on the surface of the substrate 1. S:1-02 selectively except for the top surface of the light emitting region 6
An insulating film 7 made of the following materials is formed. Next, electrode layers 8.9 made of gold (Au) are formed on the front surface of the substrate 1 including the insulating film 7, and the back surface of the substrate 1, respectively.

The steps up to this point are the same as the conventional method. However, in the present invention, next, Si is deposited on the electrode layer 9 on the back surface of the substrate.
An oxide insulating film made of O2 is deposited, and the insulating film is selectively coated on the 'clt1 layer 9 on the back surface of the substrate in a predetermined element isolation region serving as a boundary between each laser element. Then, patterning is performed to form an insulating film pattern 31 as shown in FIG. and the insulating film pattern 3
A thick gold plating layer 32 having a thickness of about several thousand meters is formed on the electrode layer 9 coated with the gold plating layer 3 by, for example, a plating method.

In this case, the gold plating layer 32 is not forged onto the insulating film pattern 31''2, as shown in FIG. 2, so that the elements are substantially isolated. Therefore, by using the area of the AiJ insulating film backing 31 that is not plated with gold and cleaving the edge portions 88, 84, and 85, it is possible to easily control a plurality of laser elements 36 as shown in FIG. Obtainable.

The semiconductor laser device 36 obtained in this manner is transferred to the heat sink base 1 through the electrode layer 8 connected to the top layer 4.
If the gold ribbon lead 18 is bonded to the other electrode made of the thick gold plating layer 32 through the wire, the electrode is formed of the thick gold plating layer 32. , the gold plating layer 3
2 and alloyed with PbT easily convert the p-conductivity on the element side into PbT type.
e The inconvenience of increasing connection resistance without reaching the semiconductor region and making contact is eliminated, and the gold ribbon lead 13 is connected to the thick gold plating layer 32 through the process n.
Because it is connected in an alloyed form with the electrode consisting of
The adhesive strength is also improved.

(0) Effects of the Invention As is clear from the above explanation, according to the method for manufacturing a semiconductor laser device according to the present invention, the electrode layer to which the gold ribbon leads of the semiconductor substrate on which a plurality of mesa stripe light emitting regions are to be connected is , it is possible to easily form a thick layer using a plating method without interfering with device separation by cleaving the substrate in the final process.Therefore, gold ribbon leads can be attached to the electrodes made of the thick gold plating layer through a process. This type of bonding eliminates the disadvantage of increasing connection resistance as in conventional methods, and also has the advantage of improving the adhesive strength of the gold ribbon leads, making it possible to obtain highly reliable semiconductor laser devices. It is extremely advantageous to apply not only to the manufacture of lead chalcogen-based compound semiconductor laser elements but also to the manufacture of other compound semiconductor laser elements, and excellent practical effects are exhibited.

[Brief explanation of drawings]

1 and 2 are perspective views illustrating a conventional method for manufacturing a semiconductor laser device, and FIGS. 3 to 6 are perspective views illustrating an example of a method for manufacturing a semiconductor laser device according to the present invention in the order of steps. It is. In the drawing, l is a compound semiconductor substrate, 2 is a buffer layer, 3 is an active layer, 4 is a top layer, 5 is a striped groove,
6 is a mesa stripe light emitting region, 7 is an insulating film, 8.9 is an electrode layer, 31 is an insulating film pattern, 82 is a gold plating layer, 83
, 34 and 35 are edge portions, and 36 is a semiconductor laser element. Figure 1 Figure 2 j Figure 3 Figure 4

Claims (1)

[Claims] A plurality of mesa stripe-shaped light emitting regions are provided parallel to each other on the surface of a compound semiconductor substrate, an insulating film is selectively deposited on the surface of the substrate other than the top surface of each light emitting region, and then an insulating film is formed on the entire surface of the substrate. After depositing a metal vapor deposited film on the upper surface and the back surface of the substrate, selectively forming an insulating film in an element isolation region serving as a boundary between each laser element on the metal vapor deposited film on the back surface of the substrate; A semiconductor laser device comprising the steps of: depositing a metal layer on the metal vapor deposited film except on the insulating film; and dividing the semiconductor laser device into a plurality of semiconductor laser devices by separating the insulating film portion. manufacturing method.