JPS62226685A - Semiconductor laser with plasma protective film and manufacture thereof - Google Patents

Abstract

PURPOSE:To stabilize element characteristics by coating a side surface including the exposed surface of an active layer with a hetero-junction on a compound semiconductor substrate with a plasma nitride film. CONSTITUTION:An active layer 33 with a predetermined hetero-junction 32 and AlGaAS 53 are superposed onto a GaAs substrate 31, and elec trodes 34,35 are attached according to a prescribed manner. CVD Si3N4 36 is plasma-formed on the side surface of the active layer 33 containing the hetero-junction. An Au wire 37 is joined with the electrode 34, and the back electrode 35 is soldered 38 to a base 39, thus completing a semiconductor laser 40 with a plasma protective film having striped structure. A buried structure type can be shaped approximately similarly. According to the constitution, the side surface of the active layer is coated with the Si3N4 film 36 with excellent adhesive properties, and an oxide and a carbide do not adhere on the active layer 33 directly and the active layer is kept extremely purely, thus stably displaying superior characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a half-75 laser with a plasma protective film and a method for manufacturing the same.

[Prior art and its problems] Conventionally, a semiconductor laser with a stripe structure has been manufactured in the following manner. First, as shown in FIG. 3(4), an active layer 3 with a predetermined heterojunction 2 formed on a GaAa substrate 1 and an AtGaAs layer 54 are sequentially provided. Eight-
Predetermined electrodes 4.5 connected to the substrate 1 are formed.

Next, as shown in FIG. 3(B), AtGaAs was
A 6-ft electrode cover is attached to the electrode 4 on the electrode 4, and using this as a mask, a dielectric film 8 is formed to cover the GaAs substrate 1 and the source surface 7, which is the side surface of the active layer 3. The dielectric film 8 is
For example, it is formed using a 5IO2 film, a Sl, N4 film, or an At203 film.

Next, as shown in FIG. 3(C), an opening 1 is formed for connecting the extending wire 9 to the electrode 4 on the AtGaAB layer 54.
0, the electrode cover 6 is removed.

Thereafter, as shown in FIG. 3(2), a gondinda wire 9 is connected to the electrode 4 in the opening 10 to obtain a semiconductor laser 15 having a striped structure.

However, when the semiconductor laser 15 is obtained in this manner, it is necessary to attach the polarization cover 6 to prevent the dielectric film 8 from adhering to a predetermined region of the electrode 4 of the GaAs substrate 1 immediately after expansion and opening. Furthermore, when connecting the Zendinda gland 9, it is necessary to remove this electrode cover 6. Since the electrode cover 6 is attached and removed for each semiconductor chip, productivity and yield are significantly reduced. Further, the dielectric film 8 described above has poor adhesion because its expansion coefficient is different from that of the GaAs substrate 1. As a result, there is a problem in that good device characteristics cannot be obtained.

By the way, conventional embedded type semiconductor lasers are manufactured in the following manner, for example. First, as shown in FIG. 4(4), an active layer 17 is formed on a GaAs substrate 1 with an n-type GaAa layer 16 interposed therebetween. The active layer 17 is made of n-type AjGaAs
A heterojunction 20 is formed between the layer 1B and the p'-type ALGaAs layer 19.

A p-type GaAs layer 21 is formed on the p-type AtGaAs layer 19.

Next, as shown in FIG. 4(B), p-type GaAs ilJ
After patterning 21 into a predetermined shape, the active mzy immediately below it is also patterned in the same way.

Next, as shown in FIG. 4C, a buried layer 23 is formed by gloss turning to cover the active layer 17 and the GaAs layer 21''f.

Next, as shown in FIG. 4 (0)), the buried layer 23 is etched until the main surface of the p-type GaAa layer 21 is exposed.

Thereafter, an electrode 24 connected to the p-type GaAs layer 2 as shown in FIG. 30
get.

However, when the semiconductor laser 30 is obtained in this way, epitaxial growth is performed by cleaning the active layer 17 after etching, but oxides and carbides adhere to the interface of the heterojunction during etching and cleaning. If epitaxial growth is performed in this state, the presence of impurities such as oxides will cause leakage current, making it impossible to obtain a semiconductor laser 30 with good device characteristics with high reproducibility. .

The present invention has been made in view of these points, and provides a semiconductor laser with a plasma protective film and a method for manufacturing the same, which can obtain semiconductor lasers with a striped structure and a buried structure with excellent device characteristics at a high yield. It is something.

[Problem fK: Means for Solving] The present invention provides an active layer having a heterojunction formed on a compound semiconductor substrate, an IT pole formed on the active layer,
A semiconductor laser with a plasma protective film is provided, comprising a plasma protective film attached to a side surface of the active layer including an exposed interface of the heterojunction.

The present invention also provides a step of forming an active layer including a heterojunction using a predetermined number of main turns of electrodes provided on a main surface of a compound semiconductor substrate as a mask, and forming an active layer including an exposed interface of the heterojunction of the active layer. A method of manufacturing a semiconductor laser with a plasma protective film is characterized in that the method includes the step of covering side surfaces including the plasma protective film with a plasma protective film.

Here, the semiconductor laser to which the present invention is applied includes those with a striped structure and those with a buried structure.

In addition, it is preferable to use a plasma protective film made of a plasma nitride film or a compound of the substrate material.◎ Also, as a means of forming the plasma protective film, there is no need to grow it integrally with the substrate through plasma processing. Also,
Alternatively, a compound of the substrate material may be deposited.

In addition, as compound semiconductor substrates, GaA@, InP,
Refers to compounds consisting of other ■-v group compounds and ■-■ group compounds.

[Function] According to the semiconductor laser with a plasma protective film and the method for manufacturing the same according to the present invention, since the side surfaces of the active layer including at least the exposed interface of the heterojunction are covered with the plasma protective film, excellent device characteristics can be achieved. Semiconductor lasers having a striped structure and a buried structure can be obtained with high yield.

[Examples] Examples of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a semiconductor laser having a stripe structure. It should be noted that the explanation of the structure of the semiconductor laser with a plasma protective film will be explained along with the explanation of the manufacturing method described below.

First, as shown in FIG. 1(3), for example, a GaAs substrate 3 is
A predetermined heterojunction 32 is formed on the substrate 1, and a specific active layer 33 and an AAGaAs layer 53 are sequentially provided on the substrate.

Next, predetermined electrodes 34 and 35 connected to the AtGaAs layer 53 and the GaAs substrate 31 are formed.

Next, as shown in FIG. 1(B), the GaAs substrate 31 is deposited between the walls by, for example, parallel plate plasma CVD (Ch
chemical 'Vapor Deposition
) ' A is installed in the room A, and for example, a plasma generation condition 36 is formed on the side surface of the active layer 33 including the heterojunction under the following plasma generation conditions.

Plasma generation conditions RF' power 200W Substrate temperature
150° C., electrode distance: 20, chamber internal pressure: 0.2 TorrNH, gas flow rate: 308 CCM, processing time: about 60 minutes. Through this processing, a plasma nitride film 36 with a thickness of about 500× is formed.

After that, as shown in FIG. 1C, a bonding wire 37 made of gold wire or the like is connected to the electrode 34 on the AtGaAs layer 53, and the electrode 35 on the back side is attached to the base 3 with solder 38.
9 to obtain a semiconductor laser 40f with a stripe structure and a plasma protective film.

In a semiconductor device with a plasma protective film configured in this way, the side surfaces of the active layer 33 including the exposed interface of the heterojunction 32 are covered with the plasma nitride film 36, so that the plasma nitride film 36 and the active layer It has good adhesion with the layer 33, etc., prevents leakage current due to generation of bin poles, and can stably exhibit excellent device characteristics.

Furthermore, according to this method of manufacturing a semiconductor laser with a plasma protective film, there is no need to attach or remove the t-pole cover 6, which is required in the conventional method shown in FIG. Yield can be significantly improved.

Next, an embodiment in which the present invention is applied to a buried semiconductor laser will be described. Note that the explanation of the structure of this semiconductor laser with a plasma protective film will be explained along with the explanation of the manufacturing method described below.

First, as shown in FIG. 2(4), an n-type GaAs layer 42, an active layer 43, and a p-type GaAs layer 44 are formed on a GaAs substrate 41.
ilY rKJff layer. The active layer 43 is i −n
It is sandwiched between an AtGaAs layer 45 and a p-type ALGaAm layer 46, and has a heterojunction 47 at the junction interface.

Next, as shown in FIG. 2(B), a mask 48 of a predetermined/4 turn is placed on the p-type GaAs layer 44, selective etching is performed to pattern the p-type GaAa layer 44, and then the p-type GaAa layer 44 is patterned. The active layer 43 of is patterned in the same manner.

Next, plasma treatment was performed under the same conditions as shown in FIG. A plasma nitride film 49 having a thickness of 50 to 200 mm is formed.

Next, as shown in FIG. 2C, the mask 48 is removed and the buried layer 5θ all-plasma nitride film 49 made of high-resistance AAGaAs and the p-type GaAs layer 44 are regrown.

Next, as shown in FIG. 2(2), p-type G is added to the buried layer 50.
An etching process is performed at 1 where the main surface of the aAs layer 44 is exposed.

Thereafter, a predetermined electrode 51 connected to the exposed p-type GaAs layer 44 is formed to obtain a buried structure semiconductor laser 52 with a plasma protective film as shown in FIG. 2(E).

In such a semiconductor laser 52 with a plasma protective film, since the side surfaces of the active layer 43 including the exposed interface of the heterojunction 47 are covered with the plasma nitride film 49, oxides and carbides are not directly attached to the active layer 33. It is extremely clean without any dirt, and a high quality embedded calendar 50 is laminated thereon. As a result, excellent device characteristics can be stably exhibited.

Further, according to the method for manufacturing a semiconductor laser with a plasma protective film, the active q including the exposed interface of the heterojunction 47
Since the buried layer 50 is formed after the plasma nitride film 49 is formed on the side surface of the J4s, a semiconductor laser with excellent device characteristics can be obtained at a high yield.

[Effects of the Invention] As explained above, according to the semiconductor laser with a plasma protective film and the manufacturing method thereof according to the present invention, it is possible to easily obtain semiconductor lasers with a striped structure and a buried structure with excellent device characteristics at a high yield. It is something that can be done.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram showing a method of manufacturing a semiconductor laser with a plasma protective film to which the method of the present invention is applied, and Fig. 2 is an explanatory diagram showing a method of manufacturing a semiconductor laser with a plasma protective film to which the method of the present invention is applied. FIGS. 3 and 4 are explanatory views showing a method for manufacturing a semiconductor laser, and FIGS. 3 and 4 are explanatory views showing a conventional method for manufacturing a semiconductor laser. 31... GaAs substrate, 32... Heterojunction, 33
...active layer, 34.35...electrode, 36...plasma nitride film, 37...? Ending line, 38...
Solder, 39... Base, 40... Semiconductor laser with plasma protective film, 41... GaAs substrate, 42... N-type GaAs layer, 43... Active layer, 44 - P-type GaAs
layer, 45- n-type AtGaAs layer, 46... p-type AtGaAs layer, 47... heterojunction, 48... mask, 49... plasma nitride film, 50... buried layer, 51 ... Electrode, 52 ... Semiconductor laser with plasma protective film Applicant's agent Patent attorney Takehiko Suzue Figure 1 Silk 4rI! I

Claims (4)

[Claims] (1) An active layer having a heterojunction formed on a compound semiconductor substrate, an electrode formed on the active layer, and plasma deposited on the side surface of the active layer including the exposed interface of the heterojunction. A semiconductor laser with a plasma protective film, characterized by comprising a protective film. (2) A semiconductor laser with a plasma protective film according to claim 1, wherein a stripe-type semiconductor laser is constituted by an active layer having a heterojunction. (3) A semiconductor laser with a plasma protective film according to claim 1, wherein a buried type semiconductor laser is constituted by an active layer having a heterojunction. (4) forming an active layer including a heterojunction using a predetermined pattern of electrodes provided on the main surface of the chemical semiconductor substrate as a mask, and plasma-forming the side surface of the active layer including the exposed interface of the heterojunction; A method for manufacturing a semiconductor laser with a plasma protective film, comprising the step of covering with a protective film.