KR20050066691A - A manufacturing method of semiconductor laser diode - Google Patents

Abstract

The present invention relates to a method of manufacturing a semiconductor laser diode, the method of manufacturing a semiconductor laser diode according to the present invention is an n-type cladding layer, an active layer, a p-type first cladding layer, an etching barrier layer (ESL), p on an n-type substrate After growing the second type cladding layer and the p-type cap layer sequentially, the p-type cap layer and the p-type second cladding layer are etched to form a ridge, and a current blocking layer ( CBL) and a p-type cap layer are grown to deposit electrodes on the p-type cap layer and the n-type substrate, respectively, to form electrodes. By using AlGaAs instead of AlGaInP, it is possible to easily form a ridge in one etching, thereby simplifying the manufacturing process of the 650 nm laser diode.

Description

A manufacturing method of semiconductor laser diode

The present invention relates to a method for manufacturing a laser diode, and more particularly, in manufacturing a laser diode having a wavelength of 650 nm, it is possible to easily form a ridge by changing some of the conventional laminated materials to other materials. And a simplified 650 nm semiconductor laser diode manufacturing process. Recently, optical storage devices have been gradually replaced from CD-ROM / RW to DVD-ROM / RW. The CD-ROM / RW uses a laser diode with a wavelength of 780 nm and the DVD-ROM / RW uses a laser diode with a wavelength of 650 nm. Optical storage devices with short wavelengths can store much larger amounts of data, making 650nm laser diodes a popular destination. However, the technology of manufacturing 650nm laser diodes is known to be much more difficult than the technology of manufacturing 780nm laser diodes. The reason for this is that in manufacturing a conventional 650 nm laser diode as shown in FIG. 1C, AlGaInP is used instead of AlGaAs used as a p-type cladding material in a 780 nm laser diode. It is difficult to grow a film having crystallinity, and as shown in FIG. 1A, when not only the p-type first cladding layer 4 but also the p-type second cladding layer 6 is AlGaInP, the p-type second cladding layer 6 In order to deposit a cap layer (8) on GaAs, it is necessary to separately grow a middle layer (7) with InGaP to alleviate the difference due to the difference in the lattice structure of the two materials, as shown in FIG. This is because the process of forming a ridge by etching the cap (8) layer, the intermediate layer (7) and the p-type second cladding layer (6) is also more complicated in the 780 nm laser diode.

That is, there is dry etching as an etching method for making a ridge of a conventional 650nm laser diode, but in this case, by using gas such as BCl ₃ , Cl ₂ , Ar in a reactive ion etching (RIE) device, Phosphorus damage (damage) can be given, it should be by a wet etching method, there is a problem that the wet etching must go through several steps in the conventional structure as described above. For example, the GaAs cap layer is first etched using NH ₄ OH + H ₂ O ₂ + H ₂ O or N ₂ SO ₄ + H ₂ O ₂ + H ₂ O solution, and then the InGaP interlayer (7) and a portion of the p-type second cladding layer 6 of AlGaInP were etched using a HBr + H ₂ O ₂ + H ₂ O solution, and the remainder of the p-type second cladding layer 6 of AlGaInP was sulfuric acid solution. (Temperature heating) should be used to etch until an InGaP etch barrier layer (ESL: 5) is revealed.

Accordingly, it is an object of the present invention to fabricate a 650 nm laser diode by changing the p-type second cladding layer to AlGaAs instead of AlGaInP and forming a cap of p-type GaAs directly on the p-type second cladding layer. It is possible to easily form a ridge to provide a method for manufacturing a simpler 650 nm laser diode.

In order to achieve the above object, the 650nm laser diode manufacturing method proposed in the present invention is an n-type cladding layer, an active layer, a p-type first cladding layer, an etch stop layer (ESL), p-type on the n-type substrate After growing the 2 clad layer and the p-type cap layer sequentially, the p-type second clad layer and the p-type cap layer are etched to form a ridge, and a current blocking layer A layer is formed by growing a CBL) and a p-type cap layer, and depositing a metal on the upper portion of the p-type cap layer and the lower portion of the n-type substrate to form an electrode.

Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 2A to 2C.

First, as shown in FIG. 2A, an n-type buffer layer (not shown) is grown on the n-type substrate 10, and then the n-type cladding layer 20, the active layer 30, and the p-type first cladding layer 40 are sequentially formed. ), An etch barrier layer (ESL: 50), a second p-type cladding layer 60, and a p-type cap (cap: 70) layer are respectively grown (hereinafter referred to as "first growth". box).

In this case, the n-type substrate 10 and the n-type buffer layer are n-type GaAs, the n-type cladding layer 20 is n-type AlGaInP, and the active layer 30 is InGaP / AlGaInP. Well: MQW), the p-type first cladding layer 40 is p-type AlGaInP, the etch-blocking layer (ESL: 50) is InGaP, and the p-type second cladding layer 60 is p-type AlGaAs. The p-type cap layer may be p-type GaAs, respectively. Each layer growth on the n-type substrate 10 may be performed by a metal organic chemical vapor deposition (MOCVD) method.

Next, as shown in FIG. 2B, a dielectric film is deposited on the first-grown wafer to form a ridge structure, and the dielectric film is patterned into a stripe shape through a known photolithography process. , The p-type cap layer 70 and the p-type second cladding layer 60 are etched according to the pattern.

Here, SiO ₂ or Si ₃ N ₄ may be used as the dielectric layer, and etching of the p-type cap layer and the p-type second cladding layer 60 may be simultaneously performed in one step. At this time, the etching of the p-type cap (cap: 70) layer and the p-type second cladding layer 60 is a wet etching NH ₄ OH + H ₂ O ₂ + H ₂ O or N ₂ SO ₄ + H ₂ O _{A 2} + H ₂ O solution can be used (in this case 50 InGaP can serve as a complete etch stop layer).

Lastly, in order to make a 650 nm laser diode as shown in FIG. 2C, the ridge structure 80 is formed, and then a current blocking layer CBL 90 is formed on the etch barrier layer 50 while covering the side of the ridge 80. After the p-type second cladding layer 60 is grown to a height, the p-type cap (cap: 70) layer is grown on the upper surface of the ridge 80 and the current blocking layer 90 again, and the p-type cap 70) The metals 100 and 110 are deposited on the upper layer and the n-type substrate 10, respectively, and the laser diode chip is completed by a chip cleaving process around the non-absorbing region.

Wherein the growth of the current blocking layer (CBL: 90) and the second p-type cap (cap: 70) layer (hereinafter referred to as "secondary growth") is known MOCVD method as the first growth As a result, the current blocking layer CBL 90 may be formed of n-type AlGaAs, and the second p-type cap 70 may be formed of p-type GaAs. In addition, the upper metal electrode 100 of the second p-type cap layer 70 is formed by sequentially stacking Ti, Pt, and Au, and the metal electrode 110 under the n-type substrate 10. ) May be formed by sequentially stacking AuGe, Ni, and Au.

As described above, the 650 nm laser diode manufacturing method according to the present invention changes the p-type second cladding layer to AlGaAs instead of AlGaInP and forms a cap layer of p-type GaAs directly on the p-type second cladding layer. As a result, the existing 780 nm laser diode process can be applied as it is to the formation of a ridge structure, thereby simplifying the 650 nm laser diode manufacturing process.

1A and 1B are cross-sectional views illustrating a ridge forming process of a 650 nm laser diode according to a conventional method.

1C is a cross-sectional view showing a 650 nm laser diode structure by a conventional method.

2A and 2B are cross-sectional views illustrating a ridge forming process of a 650 nm laser diode according to the present invention.

Figure 2c is a cross-sectional view showing a 650nm laser diode structure according to the present invention.

<Description of the symbols for the main parts of the drawings>

1, 10: n-type substrate (n-type GaAs) 2, 20: n-type cladding layer (n-type AlGaInP)

3, 30: active layer (MQW) 4, 40: p-type first cladding layer (p-type AlGaInP)

5, 50: etching barrier layer (InGaP) 6: p-type second cladding layer (p-type AlGaInP)

60: p-type second cladding layer (p-type AlGaAs) 7: intermediate layer (InGaP)

8, 70 p-type cap layer (p-type GaAs) 80: ridge

9: current blocking layer (n-type AlInP) 90: current blocking layer (n-type AlGaAs)

11, 100: p-side metal electrode (Ti / Pt / Au) 12, 110: n-side metal electrode (AuGe / Ni / Au)

Claims (5)

First to sequentially grow an n-type cladding layer, an active layer, a p-type first cladding layer, an etch stop layer (ESL), a p-type second cladding layer and a p-type cap layer on the n-type substrate Steps; Forming a ridge by etching the p-type cap layer and the p-type second cladding layer according to a pattern until the etching stop layer (ESL) is exposed; The current blocking layer (CBL) is grown on the etch stop layer (ESL) to cover the side of the ridge to the height of the p-type second cladding layer, and the ridge and the current are formed on the etch stop layer (ESL). Re-growing the p-type cap layer on the entire upper surface of the blocking layer CBL; And a fourth step of forming an electrode by depositing metal on an upper portion of the p-type cap layer and a lower portion of the n-type substrate. The method of claim 1, And the p-type second cladding layer of the first step is made of AlGaAs, and the p-type cap layer is made of p-type GaAs. The method of claim 2, The n-type substrate of the first step is n-type GaAs, the n-type cladding layer is n-type AlGaInP, the active layer is made of In-GaP / AlGaInP, Multi-Quantum Well (MQW), p-type first cladding layer Silver p-type AlGaInP, etch blocking layer (ESL) is InGaP, the third step current blocking layer (CBL) is n-type AlGaAs, p-type cap layer is p-type GaAs, The metal electrode on the four-step p-type cap layer is formed by stacking Ti, Pt, and Au, and the metal electrode on the bottom of the n-type substrate is formed by stacking AuGe, Ni, and Au. Laser diode manufacturing method. The method of claim 2 or 3, And etching the p-type second cladding layer and the p-type cap layer for forming the ridges of the second step by wet etching. The method of claim 4, wherein The wet etching of the second step is a method of manufacturing a laser diode, characterized in that using NH ₄ OH + H ₂ O ₂ + H ₂ O or N ₂ SO ₄ + H ₂ O ₂ + H ₂ O solution.