JPH05235487A - Manufacture of light-emitting semiconductor device - Google Patents

Abstract

PURPOSE:To improve bonding performance between a dielectric film and a semiconductor layer, reliability of a light-emitting semiconductor device, and its manufacturing yield, by using polyimide as an etching mask for forming a ridge, and by forming dielectric films on both sides of the ridge with the use of a lift-off method. CONSTITUTION:First of all, an n-GaAs clad layer 3, a GRIN-SCH-DQW activating layer 4, a p-AlGaAs clad layer 5, and a p-GaAs cap layer 6 are successively grown on an n-GaAs substrate 1 by a metal organic vapor phase epitaxial growth system. A polyimide 12 is formed in stripe as an etching mask on the cap layer 6. Then, etching is applied to both of the cap layer 6 and the clad layer at a time to form a ridge 11. Subsequently, an alumina film 7 is made grown by sputtering method, and an alumina film 7A bonded on the ridge 11 is immersed in ammonium sulfide, and then the alumina film 7A is eliminated together with the polyimide 12. As a result, an alumina-buried layer 7 is formed on both sides of the ridge 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ridge waveguide type semiconductor light emitting device having a dielectric layer as a buried layer. The semiconductor light emitting device includes a semiconductor laser and a semiconductor light emitting diode.

[0002]

2. Description of the Related Art A ridge waveguide type semiconductor light emitting device having a buried layer of a dielectric layer on a semiconductor layer can be manufactured by a single crystal growth, and has a thermal conductivity equal to or higher than that of a semiconductor crystal. It has an advantage that it has excellent thermal characteristics.

An example of the structure of a ridge waveguide type semiconductor light emitting device using a dielectric material as an embedding material is shown in FIG. This semiconductor light emitting device was developed by the applicant (for example, Spring 1990 Applied Physics Proceedings Third Volume 28a-S).
A-9). Since the structure of the ridge waveguide type semiconductor light emitting device will be clarified by explaining the manufacturing process thereof in FIG. 2, a method of manufacturing the semiconductor light emitting device will be described with reference to FIG.

On the n-GaAs substrate 1, n-GaAs buffer layer 2, n-AlGaAs cladding layer 3, GRIN-SCH
-DQW active layer 4, p-AlGaAs cladding layer 5, p-G
The aAs cap layer 6 is sequentially formed. A stripe-shaped etching mask is used as a photoresist 13 on the cap layer 6.
(For example, AZ resist) (FIG. 3)
(A)). Next, the ridge portion 11 is formed by etching the portions of the clad layer 5 and the cap layer 6 which are not covered with the etching mask (FIG. 3 (B)). Further, alumina 7 is grown on the entire surface of the semiconductor wafer by a sputtering method or an electron beam evaporation method to form a buried layer on both sides of the ridge portion 11 (FIG. 3 (C)). Finally, the photoresist 13 used as a mask when forming the ridge and the alumina 7 deposited on the ridge are removed by a lift-off method so that the upper surface of the semiconductor light emitting device becomes flat. Cr / A on top of device
The up electrode 8 and the AuGeNin electrode 9 are formed on the lower surface (FIG. 3D).

In order to improve the adhesion between the alumina 7 which is a dielectric film and the semiconductor layer, it has been proposed to insert an adhesion medium such as Cr between the alumina 7 and the semiconductor layer and in the alumina ( JP-A-3-145173).

[0006]

The conventional ridge waveguide type semiconductor light emitting device manufactured by the manufacturing method described with reference to FIG. 3 has the following problems.

That is, in the method of forming the dielectric film shown in the step of FIG. 3C, the alumina is liable to peel off due to the poor adhesion between the alumina and the semiconductor layer.

It is generally known that if the substrate is heated during the growth of the alumina layer 7, the adhesion between the alumina and the semiconductor layer is improved, but the photoresist used as an etching mask is hardened and cured by heating the substrate. The lift-off method cannot be used because of deterioration, and the manufacturing process becomes complicated.

According to the method of inserting the adhesion medium such as Cr between the alumina and the semiconductor layer and into the alumina for improving the adhesion, current leakage occurs due to the metal such as Cr and the semiconductor light emitting device It adversely affects the electrical characteristics.

The present invention solves the above problems.

[0011]

DISCLOSURE OF THE INVENTION According to the present invention, in a method of manufacturing a ridge waveguide type semiconductor light emitting device having a dielectric film as a ridge burying layer on a semiconductor layer, polyimide is used as an etching mask for forming a ridge portion, and lift-off is performed. The dielectric film is formed on both sides of the ridge by the method. The substrate is heated when the dielectric film is formed. After forming the dielectric film, an ammonium sulfide solution is used when removing the polyimide mask.

[0012]

The present invention has the following effects due to the above configuration.

Since polyimide is used as an etching mask instead of photoresist, even if the substrate is heated to improve the adhesion between the dielectric film and the semiconductor layer during the growth of the dielectric film, the etching The mask does not harden and deteriorate. Therefore, the polyimide and the alumina deposited on the ridge can be removed by the lift-off method so that the upper surface of the semiconductor light emitting device becomes flat.

As a result, the adhesion between the dielectric film and the semiconductor layer is improved, and the reliability and the manufacturing yield are improved. Also,
Since the ammonium sulfide solution is used to remove the polyimide, the oxide film on the surface of the cap layer that forms the ridge during lift-off is also removed at the same time, and improvement of the ohmic electrode can be expected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a ridge waveguide type semiconductor light emitting device which is an embodiment of the present invention will be described below with reference to FIG.

First, a metal organic chemical vapor deposition method (MOCVD method)
Or, by the molecular beam epitaxy method (MBE method), etc.
-On a GaAs substrate 1, a 1.0 μm thick n-GaAs buffer layer 2, a 1.5 μm thick n-AlGaAs clad layer 3, a GRIN-SCH-DQW active layer 4, a 1.5 μm thick p-AlG.
An aAs clad layer 5 and a 1 μm thick p-GaAs cap layer 6 are sequentially grown.

Polyimide 12 is formed on the cap layer 6 as an etching mask in the form of a stripe having a width of 5 μm (FIG. 1 (A)).

Then, the cap layer 6 and the cladding layer 5 are combined and etched by about 2.3 μm (that is, the cladding layer 5 is slightly left) to form a ridge 11 (FIG. 1).
(B)).

Subsequently, the alumina film 7 having a thickness of 2 μm is grown by the sputtering method or the electron beam evaporation method (FIG. 1 (C)). The substrate temperature at this time is 250 degrees. 5 μm
The alumina film adhered on the ridge 11 having the width (particularly indicated by reference numeral 7A in FIG. 1C) is dipped in an ammonium sulfide solution and removed together with the polyimide 12. As a result, the buried layers 7 made of alumina are formed on both sides of the ridge 11.

Finally, an electrode 8 made of Cr / Au is deposited on the upper part of the element, and an electrode 9 made of AuGeNi is deposited on the lower part (FIG. 1 (D)).

Through the above manufacturing steps, the ridge waveguide type semiconductor light emitting device using alumina of the dielectric film shown in FIG. 2 as a filling material is completed.

[Brief description of drawings]

1A to 1D are cross-sectional views showing a manufacturing process of a ridge waveguide type semiconductor light emitting device using a dielectric material using polyimide as an etching mask as a filling material according to an embodiment of the present invention. is there.

FIG. 2 is a cross-sectional view of a ridge waveguide type semiconductor light emitting device using a dielectric as a filling material.

3A to 3D are cross-sectional views showing a manufacturing process of a ridge waveguide type semiconductor light emitting device using a dielectric as a filling material according to a conventional example.

[Explanation of symbols]

 1 n-GaAs substrate 2 n-GaAs buffer layer 3 n-AlGaAs clad layer 4 GRIN-SCH-DQW active layer 5 p-AlGaAs clad layer 6 p-GaAs cap layer 7 alumina layer (embedded layer) 8 Cr / Aup electrode 9 AuGeNin electrode 11 Ridge part 12 Polyimide (etching mask)

Claims (3)

[Claims] 1. In a ridge waveguide type semiconductor light emitting device having a dielectric film as a ridge burying layer on a semiconductor layer, polyimide is used as an etching mask for forming a ridge portion, and a dielectric is formed on both sides of the ridge by a lift-off method. A method for manufacturing a semiconductor light emitting device, which comprises forming a film. 2. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein the substrate is heated when the dielectric film is grown. 3. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein an ammonium sulfide solution is used for removing the polyimide mask.