KR100275770B1 - Method for manufacturing semiconductor laser device - Google Patents

Abstract

PURPOSE: A method for manufacturing a semiconductor laser device is provided to facilitate diffusion control and to prevent efficiency degradation of the device in accordance with introduction of dopant of p-clad layer into an active layer by annealing the active layer into disordered state using laser. CONSTITUTION: On a first conductive semiconductor substrate(21) are successively deposited a first conductive clad layer(23), an active layer(24), a second conductive clad layer(25), an easy-conductive layer(26) and a cap layer(27) to form a laser oscillated layer. An impurity dispenser layer consisting of Si3N4 is formed on the laser oscillated layer. A laser beam is irradiated on a region of impurity dispenser layer excluding a stripe region so that a silicon atom in the impurity dispenser layer is diffused into the first conductive clad layer, the active layer, the second conductive clad layer, the easy-conductive layer and the cap layer to form a diffusion region. The impurity dispenser layer is removed to expose the cap layer. A metal electrode is formed under the substrate and on the cap layer.

Description

Manufacturing Method of Semiconductor Laser Device

1 is a cross-sectional view showing a semiconductor laser diode manufactured by using a phenomenon in which a superlattice is changed into an disordered layer by a conventional impurity diffusion,

2 (a) to 2 (e) are cross-sectional views illustrating an example of a method of manufacturing a laser diode device according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly, to a method for manufacturing a refractive index waveguide semiconductor laser device that can be manufactured by a first epitaxial growth process using an interlayer disorder phenomenon using a laser beam. .

A semiconductor laser device is a semiconductor device based on a PN junction structure. It injects a current into an active layer, which is a thin film made of a semiconductor material, and artificially induces electron-hole recombination to emit light corresponding to the reduced energy caused by these recombinations. As a semiconductor diode, a magneto optical disk drive (MODD) barcode reader, a laser beam printer, and the like are widely used. In order to increase the density of storing and reading information, the wavelength of the semiconductor laser used as the light source should be reduced and the output should be increased.

The semiconductor laser diode is manufactured by epitaxially growing InGap / InGaAlP-based three- and four-membered mixed crystal group III-V materials on a GaAs semiconductor substrate. As such, epitaxial growth includes liquid phase epitaxy (LPE), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and the like. Can be mentioned. Recently, the concept of quantum wells and strained layers has been introduced into laser diodes, and there is a need to control the exact thickness of thin films. Therefore, it is common to manufacture semiconductor lasers mainly by vapor phase growth methods such as the MOCVD method and the MBE method.

In general, in order to manufacture a refractive index waveguide semiconductor laser device, the epitaxial growth process and the etching process are performed. However, in the case of performing the etching process, it is difficult to accurately etch a layer formed of multiple layers by the epitaxial growth process as described above, and thus productivity is lowered.

In addition, when the second epitaxial regrowth process is performed after the first epitaxial growth process, the epitaxial layer that has been exposed to the atmosphere during the etching process is oxidized to obtain a high quality crystal film when the regrowth process is performed. Is hard. In addition, since the second epitaxial growth process must be performed after the etching process, it is very difficult to form a flat layer when performing the vapor phase growth method on the etched substrate.

In order to overcome this problem, Japanese Patent Laid-Open No. 4-321291 has proposed a laser diode which can be manufactured only by a first epitaxial growth process by using a phenomenon in which a superlattice is changed into a disordered layer by diffusing impurities. .

1 is a cross-sectional view showing a semiconductor laser diode manufactured by using the phenomenon in which the superlattice is changed into an disordered layer by the above-described conventional impurity diffusion.

Referring to FIG. 1, an n-InGaAlP first cladding layer 3 is formed below the active layer 4, and a p-InGaAlP second cladding layer 5 is formed thereon to form a laser oscillation layer. . An n-GaAs buffer layer 2 is provided below the laser oscillation layer, and the buffer layer 2 and the laser oscillation layer are formed on the n-GaAs substrate 1. A p-InGaP conducting layer 6 is formed on the laser oscillation layer, a p-GaAs cap layer 7 is formed thereon, and an oxide source, which is an impurity source, is formed on the cap layer 7. Alternatively, an insulating film pattern 12 made of silicon nitride is formed. The insulating layer pattern 12 exposes a current passing region of the cap layer, and an impurity-illuminated disordered region 13 formed by diffusion of impurities such as silicon is disposed below the insulating layer pattern 12 except for the current passing region. The site | part is formed over a part of the cap layer 6, the 2nd cladding layer 5, the active layer 4, and the 1st cladding layer 3. As shown in FIG. In addition, an n-metal electrode 11 is formed below the substrate, and a p-metal electrode 10 is formed on the insulating layer 12 and the cap layer 7.

In order to manufacture the semiconductor laser diode device described above, a buffer layer 2, a first cladding layer 3, an active layer 4, and a second cladding layer 5 are formed on the substrate 1 by an epitaxial growth method. ), The energizing bilayer 6 and the cap layer 7 are sequentially grown. Next, an insulating film serving as an impurity dispenser layer is formed on the cap layer 7, and then the current path (current passing region) of the laser oscillation layer and the cap layer 7 is exposed to the insulating film. The openings are formed by a normal photolithography process to form the insulating film pattern 12. Next, the epitaxial layer on which the insulating film pattern is formed is heat-treated at a high temperature so that impurities such as Si present in the impurity supply layer diffuse into the epitaxial layer to induce interlayer disorder, as shown in the cap layer 7, An disordered region is formed over a portion of the current carrying layer 6, the second cladding layer 5, the active layer 4, and the first cladding layer 3. This interlayer disorder increases the energy band gap and lowers the refractive index to form a refractive index waveguide structure. Subsequently, an n-metal electrode 11 is formed below the substrate 1, and a p-metal electrode 10 is formed on the insulating layer 12 and the cap layer 7 to complete the illustrated semiconductor laser device. .

According to the above method, the semiconductor laser device can be manufactured simply by performing only the first epitaxial process. However, since the semiconductor laser diode of the above structure is not a self-aligned structure, the impurity supply layer must be patterned to form a current path and a predetermined disordered region, and a separate photolithography process is required for this purpose. . In addition, in order to diffuse the impurities, a high temperature heat treatment must be performed. During the high temperature heat treatment, impurities of the second cladding layer of p-InGaAlP flow into the active layer to act as a center of the non-luminescent bond, thereby lowering the efficiency of the device. However, in devices with low heterogeneous barriers, oscillation itself becomes difficult and there is a problem in practical use.

Accordingly, it is an object of the present invention to provide a method for manufacturing a semiconductor laser device which can easily form a disordered region of a semiconductor laser device while solving the above problems while maintaining the advantages of the laser device by the impurity phenomenon described above.

In order to achieve the above object of the present invention, the present invention is characterized in that by forming a disordered region by selectively heating the epitaxial layer formed with an insulating film composed of an impurity source using a laser beam.

Specifically, according to the present invention, forming a laser oscillation layer by sequentially forming a first conductive first cladding layer, an active layer and a second conductive second cladding layer on the first conductive semiconductor substrate;

Forming an impurity supply layer on the laser oscillation layer; And

The laser beam is partially scanned on the impurity supply layer except for the stripe region, and the impurity from the impurity supply layer is diffused to a part of the first clad layer, the active layer and the second clad layer to partially disassemble the disordered region. There is provided a method of manufacturing a semiconductor laser device comprising the step of forming. The impurity supply layer may be formed using, for example, an insulating material such as silicon nitride. In the specific manufacturing method of the present invention, after doping the first conductive type impurity in the disordered region, an electrode is formed to complete the laser device.

According to the present invention, the directionality is imparted to the diffusion of impurities by the laser beam, so that the diffusion can be easily controlled, and therefore, it is possible to manufacture a laser device having excellent characteristics. In addition, since the active layer is locally heated using a laser to cause disorder, the problem caused by the dopant of the p-clad layer entering the active layer is eliminated as in the conventional method, thereby increasing the efficiency and reliability of the device. .

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

2 (a) to 2 (e) are cross-sectional views illustrating an example of a method of manufacturing a laser diode device according to the present invention.

Referring to FIG. 2 (a), the n-type GaAs buffer layer 22 and the n-type InGaAlP first cladding layer are formed on the n-type GaAs semiconductor substrate 21 by using a vapor deposition method such as MOCVD or MBE. 23), an InGaP active layer 24, a p-type InGaAlP second cladding layer 25, a p-type InGaP passivation layer 26 and a p-type GaAs cap layer 27 are sequentially stacked to form an epitaxial layer. .

Referring to FIG. 2 (b), a silicon nitride film 28 to be used as an impurity supply layer is formed on the cap layer 27 by a conventional CVD method.

Referring to Figure 2 (c). The laser beam 30 is scanned on the substrate at portions other than the stripe region defining the current path of the epitaxial layer.

As described above, as a method of selectively scanning a laser beam, the laser beam 30 may be moved by a method of moving the laser beam along a predetermined path or by fixing the laser beam and moving the substrate, for example, according to a computer program. ) May be selectively scanned into the insulating film 28. At this time, the insulating layer 28 is locally heated by the scanned laser beam 30 so that the silicon atoms in the insulating film 28 have the cap layer 27, the conductive layer 26, and the second cladding layer ( 25), the active layer 24 and the first cladding layer 23 are diffused to form a diffusion region 29. In the region into which the silicon is diffused, a super lattice disorder occurs to increase the energy band gap, while the refractive index is lowered, thereby changing the refractive index of the device in the transverse direction. Therefore, since refractive index oscillation is possible and n-type impurities are implanted in this region, even if the p-type metal is entirely deposited on the cap layer 27, current passes only through the active region where impurity diffusion does not occur. Done. In addition, since diffusion occurs under the impurity supply layer using a laser beam, the diffusion of impurities is directional, thereby facilitating control of diffusion.

Referring to FIG. 2 (d), after the laser beam 30 is irradiated, the masking pattern and the insulating layer 28 are removed, and then n-type impurities are selectively added to the impurity diffusion region 29. Doping with

Referring to FIG. 2 (e), n-metal is deposited on the lower portion of the substrate 21 to form an n-metal electrode 31, and p-metal is deposited on the cap layer 27 to p. The metal electrode 32 is formed to complete the laser device of the present invention.

The manufacturing method of the semiconductor laser device of this invention has the following advantages.

1) Since the laser device can be manufactured only by the first epitaxial growth process, productivity is improved.

2) Compared with the prior art, the step of forming the opening after the deposition of the insulating film can be omitted, and the disordered phenomenon is selectively caused by the self-matching type, so the process is simple and the productivity is high.

3) The directionality is imparted to the diffusion of impurities by the laser beam, so that the diffusion can be easily controlled, and therefore a laser device having excellent characteristics can be manufactured.

4) In addition, since the active layer is locally heated by using a laser to cause disorder, the problem caused by the dopant of the p-clad layer flowing into the active layer is eliminated as in the conventional method, thereby improving efficiency and reliability of the device. Increases.

As mentioned above, although this invention was demonstrated to an Example, this invention is not limited to this, A deformation | transformation and improvement are a matter of course within the range of common knowledge of a person skilled in the art.

Claims (2)

Forming a laser oscillation layer by sequentially forming a first conductive first cladding layer, an active layer and a second conductive second cladding layer, an electricity transfer layer, and a cap layer on the first conductive semiconductor substrate; Forming an impurity supply layer made of silicon nitride (Si ₃ N ₄ ) on the laser oscillation layer; The laser beam is scanned on the impurity supply layer except for the stripe region, and the silicon atoms in the impurity supply layer are diffused into the first cladding layer, the active layer, the second cladding layer, the transfer layer, and the cap layer. Forming a diffusion region; Removing the impurity supply layer to expose the cap layer; And forming a metal electrode under the substrate and on the cap layer. The method of claim 1, further comprising doping the first conductive type impurity in the diffusion region.