KR100239498B1 - Method for manufacturing semiconductor laser diode - Google Patents

Abstract

The method of manufacturing a semiconductor laser diode is to simplify three chemical etching processes and three epitaxial growth processes in manufacturing a semiconductor laser diode according to the prior art, and includes an undoped AlGaAs layer and an undoped layer on a first conductive substrate. Depositing a GaAs layer and an insulating film for use as a mask and a current blocking film for selective growth in a subsequent process, and removing the vicinity of the center of the insulating film in a rectangular shape by a photo etch process and etching to the substrate surface using the mask as a mask And depositing a first conductive cladding layer, an active layer, a second conductive cladding layer, and a high concentration first conductive cap layer on the etched rectangular portions in order, and on the high concentration first conductive cap layer and below the substrate. The second conductive electrode and the first conductive electrode are respectively formed in the process. have.

Description

Semiconductor laser diode manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor laser diodes, and more particularly to a method for fabricating a semiconductor laser diode to simplify a complex epitaxy growth process for obtaining high power.

Conventional laser diodes for obtaining high power of 100mV or more used a structure called NAM-BTRS (Non-Absorbing Mirror-Buried Twin Ridge Structure).

Hereinafter, a semiconductor laser diode manufacturing method according to the related art will be described with reference to the accompanying drawings.

1 (a) to 1 (f) are perspective views showing a process of a semiconductor laser diode according to the prior art. As shown in FIG. 1 (a), a chemical etching process is performed on a p-type GaAs substrate 1. First mesa is formed, and as shown in FIG. 1 (b), an n-type GaAs current blocking layer 2 is grown on the front surface by using a Liquid Phase Epitaxy (LPE) method.

As shown in FIG. 1 (c), the n-type GaAs current blocking layer 2 is selectively etched by chemical etching to form V-grooves and secondary mesas. As shown, the p-type cladding layer 3, the p-type guide layer 4, the active layer 5, the n-type limiting layer 6 and the n-type buffer layer 7 are sequentially formed using the LPE method.

Subsequently, both mirror surfaces are removed to the active layer 5 by a photo etch process as shown in FIG. 1 (e), and MOCVD (Metal Organic Chemical Vapor Deposition) on the front surface as shown in FIG. 1 (f). The laser diode is completed by growing and planarizing the n-type cladding layer 8 by the method and forming the n-type contact layer 9 thereon.

The semiconductor laser diode manufacturing method according to the prior art is to solve the collapse of the mirror surface by the generated heat to obtain a high output, both sides of the facet (facet) to suppress the heat generated by the current injected from the mirror surface A current blocking layer was placed and the active layer was removed to minimize heat.

In addition, a clad layer having a large energy gap was placed on both mirrors to prevent light absorption as much as possible.

However, the semiconductor laser diode manufacturing method according to the related art has three chemical etching processes and three epitaxial growth processes, which makes the process complicated, and it is difficult to control the thickness of the central part when the clad layer is grown after etching both the sheets. Exposing the active layer cross section to the air causes oxidation to deteriorate device characteristics.

Therefore, the present invention has been made to solve the above problems, a semiconductor laser diode manufacturing method for simplifying the process of three chemical etching process and three epitaxy growth process in the manufacturing of semiconductor laser diode according to the prior art. The purpose is to provide.

1 (a) to 1 (f) are perspective views showing a process of a semiconductor laser diode according to the prior art.

2 (a) to 2 (d) are cross-sectional views and perspective views showing the process of the semiconductor laser diode according to the present invention.

* Explanation of symbols for main parts of the drawings

11 substrate 12 undoped Al _0.45 Ga _0.55 As layer

13: undoped GaAs layer 14: insulating film

15,17 cladding layer 16: active layer

18: cap layer 19, 20: electrode

The semiconductor laser diode manufacturing method according to the present invention for achieving the above object is, the undoped AlGaAs layer and the undoped GaAs layer on the first conductive substrate and the mask and current blocking film required for selective growth in the next process A step of depositing an insulating film for use as a sequential step, a step of removing the vicinity of the center of the insulating film in a rectangular form by a photo etch process, and etching it to the surface of the substrate using the mask as a mask; Forming a cladding layer, an active layer, a second conductive cladding layer, and a high concentration first conductive cap layer, and forming a second conductive electrode and a first conductive electrode on the high concentration first conductive cap layer and under the substrate, respectively. It consists of the process of doing.

Hereinafter, a semiconductor laser diode manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings.

2 (a) to 2 (d) are cross-sectional views and perspective views showing a process of a semiconductor laser diode according to the present invention, which are sequentially shown on the n-type GaAs substrate 11 as shown in FIG. 2 (a). Si ₃ N for use as a mask and current blocking film for growing an undoped Al _0.45 Ga _0.55 As layer 12 and an undoped GaAs layer 13 by LPE or MOCVD and selectively growing on it An insulating film 14 such as ₄ or SiO ₂ is deposited.

Then, as shown in FIG. 2 (b), a predetermined portion of the center of the insulating film 14 is opened in a rectangular shape by a photolithograph process, and the insulating film 14 is used as a mask to the surface of the substrate 11. After etching, the n-type AlGaAs cladding layer 15, the active layer 16, and the p-type AlGaAs cladding layer were removed by MOCVD on the portions removed in a rectangular shape as shown in FIGS. 2 (c) and 2 (d). 17), the p-type electrode 19 is formed over the high concentration P-type GaAs cap layer 18, and the n-type electrode 20 is formed below the substrate 11 to manufacture the semiconductor laser diode according to the present invention.

FIG. 2 (c) is a cross-sectional view taken along line AA ′, which is a narrow portion of the rectangular shape as shown in FIG. 2 (b), and FIG. 1 (d) is a rectangle as shown in FIG. 2 (b). BB 'section which is wide part of shape.

Such a semiconductor laser diode according to the present invention includes all of the features of the prior art NAM-BTRS.

That is, the current injected only to the DH (Double Heterostructure) formed near the center of the substrate flows, and the undoped AlGaAs layer formed on both facets sufficiently enlarges the energy gap, thereby suppressing the absorption of photons generated during light emission. It acts as a NAM, and AlGaAs on the facet side is undoped, so the resistance is large, limiting the current to only the central portion.

Therefore, it is possible to sufficiently suppress the heat that can be generated in the mirror surface to increase the COS (Catastrophic Optical Damage) level that influences the high output to obtain an output of 100mW or more.

As described above, the method for manufacturing a semiconductor laser diode according to the present invention simplifies the process, prevents the active layer from being exposed to air, suppresses the deterioration of device characteristics due to oxidation, and provides sufficient current limitation without providing a current limiting layer. In addition, the n-type substrate having a low defect level of the substrate itself can be used.

Claims (1)

Depositing an undoped AlGaAs layer, an undoped GaAs layer on the first conductive substrate, and an insulating film for use as a mask and current blocking film for selective growth in a subsequent step; A step of removing the vicinity of the center of the insulating film in a rectangular form by a photo etch process and etching the substrate to the surface of the substrate; Depositing a first conductive cladding layer, an active layer, a second conductive cladding layer, and a high concentration of the first conductive cladding layer on an etched rectangular portion in order; And forming a second conductive electrode and a first conductive electrode on the high concentration first conductive cap layer and under the substrate, respectively.