KR20020096375A - fabrication method in semiconductor laser device - Google Patents

Abstract

PURPOSE: A method for fabricating a semiconductor laser device is provided to remove a complicated chip bar handling process by performing directly a process at a state of wafer without a chip bar cleaving process. CONSTITUTION: An n-GaAs wafer(10), an n-clad layer(20), a quantum well(40), and an InGap layer(50) are sequentially grown by using a MOCVD(Metal-Organic Chemical Vapor Deposition) method. An SiN mask is deposited thereon by using a PECVD(Plasma Enhanced Chemical Vapor Deposition) method. The SiN mask is etched to expose the InGaP layer(50). Nitrogen ions are implanted into a ridge in order to form a mirror side(30). The SiN mask is removed. The nitrogen ions are diffused by performing a thermal process. The mirror side is formed by removing a damage due to the ion implant process. A p-clad layer(70) is grown on the InGap layer(50). A ridge is formed on the p-clad layer(70). A CBL(Current Blocking Layer) region(80) is grown on the ridge. A plurality of electrode layers(100,110) are formed by depositing a GaAs capping layer on a whole surface of the above structure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly, to a method of manufacturing a high-power semiconductor laser device that reduces COD (Catastrophic Optical Damage) to provide stable light output for a long time.

Recently, as the speed of CD-RW increases, a semiconductor laser device with high optical output has become necessary.

This semiconductor laser oscillates at a wavelength of 0.98 μm, which is used to amplify a signal passing through an optical fiber as a light source of an Erbium Doped Fiber Amplifier (EDFA). Therefore, the larger the optical output of the 0.98 탆 semiconductor laser, the greater the optical amplification factor of the EDFA, which is important for the fabrication of a 0.98 탆 semiconductor laser capable of producing a high optical output.

Generally, however, since the end portion of the optical waveguide included in the active layer, i.e., the output surface, is oxidized faster than the center portion and the bandgap becomes smaller, the laser light is absorbed and is easily heated.

However, if the optical amplification rate is increased to improve the optical output of the semiconductor laser device, the optical power density is increased in the optical output plane and the temperature of the output plane is also increased, This shortens the lifetime of the semiconductor laser.

Therefore, various methods have been tried to solve these problems.

One of them is sulfur treatment on one surface to reduce the surface state. However, this method has difficulty in obtaining contamination and reproducible conditions that can occur in a wet process.

In another method, a non-absorbing layer (window layer) is introduced by introducing a GaN layer having a larger energy bandgap than an active region, thereby effectively suppressing COD.

However, these methods have a fundamental problem.

In other words, since a substrate is first cleaved and then a chip bar is formed and then applied, a facet is exposed to the outside during cleaving, and a clean mirror surface There was a problem getting a clean mirror facet.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for handling a complicated chip bar by performing a process directly on a wafer substrate without chip bar cleaving, There is a purpose to get rid of it.

It is another object of the present invention to prevent one side of the cleaving process from being directly exposed to external oxygen or water vapor.

1 is a view showing a structure of a laser device after primary growth according to the present invention

2 is a view showing a structure of a laser device after secondary growth according to the present invention

3 is a view showing a semiconductor laser device after cleaving according to the present invention

DESCRIPTION OF THE REFERENCE NUMERALS

10: substrate 20: n-clad layer

30: mirror surface 40: active layer

50: protective layer 60: SiN mask

70: p-cladding layer 80: CBL

90: capping layer 100, 110: electrode layer

According to another aspect of the present invention, there is provided a method of fabricating a semiconductor laser device, including: a first step of successively growing a n-clad layer, an active layer having ridges, A second step of forming a SiN mask on the active layer and etching the SiN mask to expose the protective film layer at the same position as the ridge formed in the active layer; A fourth step of removing the SiN mask, diffusing implanted ions through a heat treatment process, and removing damage caused by the ion implantation process to form a mirror surface; A p-cladding layer 70 is grown on the p-cladding layer, a ridge is formed in the p-cladding layer, and a CBL region is grown on the ridge to form a channel Forming a GaAs capping layer on the entire surface, and forming an electrode layer on the entire surface.

The heat treatment in the fourth step has another characteristic in forming the mirror surface through the heat treatment process of 600 °.

The function according to the present invention is effective in suppressing COD by manufacturing a window region at the same time as passivation of one surface before mirror coating, thereby improving the reliability of the device.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Preferred embodiments of a method of manufacturing a semiconductor laser device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a view showing a structure of a laser device after primary growth according to the present invention. FIG.

1, an n-GaAs wafer 10, an n-cladding layer 20, an active layer (QW) 40, and an InGaP 50 are sequentially formed by MOCVD (organometallic compound CVD) Crystal growth.

In this case, the InGaP 50 serves as a primary mask when performing nitrogen ion implantation, masks out diffusion during subsequent heat treatment, and functions as an etch-stop layer when forming a ridge after the secondary growth. At the same time.

Then, a SiN mask 60 is deposited on the grown sample by PECVD. Then, the SiN mask 60 is left so as to maintain a ridge width of 2 to 3 占 퐉 and a channel width of 20 占 퐉 through a photolithography process, Or etched to expose InGaP (50) through a dry etching process.

The thus formed ridge is implanted with nitrogen ions by an ion implantation method.

At this time, the region into which the nitrogen ions are implanted will be the portion to be the mirror surface 30 in the future, and the concentration of the ions and the depth of implantation are determined in consideration of the device manufacturing process.

Nitrogen ion implantation must have sufficient energy to penetrate the primary mask, InGaP (50), and the implant depth is concentrated in the active area.

After the SiN mask 60 is removed, the implanted ions are diffused through a heat treatment process to remove the damage caused by the ion implantation process.

It is known that the doping profile during the diffusion process generally follows a Gaussian distribution. Therefore, the region where the nitrogen is implanted is annealed at a temperature of about 600 ° to form the GaN region 30.

The GaN layer 30 is grown on the active layer 40 in the (Al) state, since the arsenic (As) is removed while the gallium (Ga) atom is implanted with nitrogen (N) The energy gap is larger than that of GaAs, which serves as a non-absorbing layer when driving the device.

Next, the secondary process steps shown in FIG. 2 are as follows.

The p-cladding layer 70 is grown on the InGaP layer 50.

Then, a ridge shape is formed in the P-type cladding layer 70, a CBL (Current Blocking Layer) region 80 is grown on the ridge, and a channel for current injection is formed.

Finally, a GaAs capping 90 is formed on the upper portion.

Then, a p-metal (Ti / Pt / Au) 100 is deposited using an electron beam evaporator as a metallization process.

After lapping, n-metal (AuGe / Ni / Au) 110 is deposited and then the process is completed.

3 is a diagram showing a semiconductor laser device after cleaving according to the present invention.

3, an n-cladding layer 20, an active layer 40 having an optical waveguide and a GaN layer 30, a protective layer 50, a p-cladding layer 70, and a CBL Cladding layer 70 and an electrode layer 100 (110) for laminating a current blocking layer 80 and a current from the CBL 80 to the active layer 40 through the p-cladding layer 70.

The GaN layer 30 can be seen in the active layer 40 on one side because the GaN layer 30 is exposed not in the active layer 40 during the cleaving process, It is possible to perfectly protect one surface of the active layer 40 from impurities such as water vapor.

Thus, a semiconductor laser device capable of preventing COD can be provided.

The method of manufacturing a semiconductor laser device according to the present invention as described above has the following effects.

First, a GaN window layer is formed on one side of a mirror in a high power semiconductor laser device, thereby reducing light absorption near the surface, thereby suppressing COD, thereby enhancing device reliability.

Second, there is a process advantage because there is no separate cleaving process in mirror surface processing.

Third, it can be applied to all semiconductor laser diodes.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments but should be determined according to the claims.

Claims (4)

A first step of successively growing a n-clad layer, an active layer having ridges, and a protective film layer on the substrate, A second step of forming a mask on the protective film layer and etching the mask to the same position as the ridge formed on the active layer to expose the protective film layer; A third step of implanting nitrogen ions into a ridge formed in the mask using an ion implantation method; A fourth step of removing the mask, diffusing ions implanted through a heat treatment process, and removing damage caused by the ion implantation process to form a mirror surface; A fifth step of growing a p-cladding layer 70 on the protection layer, forming a ridge shape in the p-cladding layer, and growing a CBL region in the ridge to form a channel, And a sixth step of forming a GaAs capping layer on the entire surface and forming an electrode layer on the GaAs capping layer. The method according to claim 1, The protective layer functions as a first mask when performing nitrogen ion implantation, and functions as an etch-stop layer when masking out diffusion during a subsequent heat treatment and forming a ridge after second growth. Of the semiconductor laser device. The method of claim 1, wherein the SiN mask PECVD, and then forming a ridge width of 2 to 3 占 퐉 and a channel width of 20 占 퐉 through a photolithography process. The method according to claim 1, Wherein the heat treatment in the fourth step forms a mirror surface through a heat treatment process of 600 °.