KR20050087025A - Laser diode and method of manufacturing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode and a method of manufacturing the same, wherein trenches are formed on both sides of the ridge to planarize the surface of the laser diode to the same height as the ridge, thereby reducing the mechanical shock and pressure generated during the manufacturing process. Dispersion has the effect of minimizing damage to ridges.

In addition, the ridge can be protected, and the performance and yield of the device can be improved, and an effective assembly process can be enabled.

In addition, assembling is uniformly made over a larger area, it is possible to effectively dissipate heat, thereby improving the life of the device.

Description

Laser diode and its manufacturing method {Laser diode and method of manufacturing the same}

The present invention relates to a laser diode and a method of manufacturing the same, and more particularly, by forming trenches on both sides of the ridge to planarize the surface of the laser diode to the same height as the ridge to protect the ridge, The present invention relates to a laser diode and a method of manufacturing the same, which can minimize damage to ridges by dispersing mechanical shock and pressure generated in the air.

Recently, with the development of technologies related to nitride semiconductors, application fields are diversified, and corresponding markets are rapidly increasing.

One of the representative devices based on nitride semiconductors, a blue laser diode is being developed as a light source for a large capacity data storage device and a high resolution laser printer.

This blue laser diode has made significant technological advancements through active R & D activities over the past several years with light emitting diodes, but there are still no companies producing low uniformity of device characteristics and low yield.

FIG. 1 is a cross-sectional view illustrating a schematic structure of a general blue laser diode, and includes a buffer layer 11, an N-GaN layer 12, an N-AlGaN cladding layer 13, and an N-GaN wave on the sapphire substrate 10. The guide layer 14, the InGaN active layer 15, the P-GaN wave guide layer 16 and the P-AlGaN cladding layer 17 are sequentially stacked; Mesa etching is performed from the P-AlGaN cladding layer 17 to a part of the N-GaN layer 12 so that a part of the N-GaN layer 12 is exposed; A portion of the upper portion of the P-AlGaN cladding layer 17 is removed to form a ridge 17a protruding from the upper surface of the removed P-AlGaN cladding layer; A P-GaN layer 18 is formed on top of the ridge; A dielectric film (19) is formed on the entire surface of the P-GaN layer formed on the ridge to expose the upper surface of the N-GaN layer (12); A P-electrode 22 is formed surrounding the exposed P-GaN layer; An N-electrode 21 is formed to surround the exposed N-GaN layer 12.

In this case, the dielectric layer 19 is formed on the P-AlGaN cladding layer 17, the N-GaN layer 12, and the mesa etched side, as shown in FIG. 1.

The dielectric film is applied for passivation and transverse mode control for leakage current removal.

Such a conventional laser diode is formed in a structure in which the ridge is protruded, and a lot of impact is applied to the ridge manufacturing process, which causes the ridge to be damaged, thereby increasing the threshold current (I _th ) or lasing. It may be.

In particular, as shown in Fig. 2, in the scribing process of cleavage formation or chip separation, the wafer 50 on which the laser diode is manufactured is inverted and processed into the scribing tip 61, and all mechanical pressures protrude. The ridge 51 is easily damaged by concentrating on the ridge 51.

3 is a cross-sectional view showing a state in which a laser diode according to the related art is assembled. In order to assemble the laser diode 55, an N electrode (using solders 31 and 32 to a heat sink 70 that is a heat radiating medium) is used. 21) and the P-electrode 22, where the bonding with the heat sink is not evenly made with the entire electrode area, and only the protruding ridge portion may be combined.

Therefore, all the heat generated in the device is not effectively released through the entire surface, but only through the narrow ribs, which may lower device reliability.

The present invention is to solve the problems described above, by forming trenches on both sides of the ridge (Ridge) to planarize the surface of the laser diode to the same height as the ridge to protect the ridge, the mechanical generated during the manufacturing process It is an object of the present invention to provide a laser diode and a method of manufacturing the same, which can minimize damage to the ridge by dispersing impact and pressure.

Another object of the present invention is to project the ridges between the trenches, to protect the ridges, to improve the performance and yield of the device, to enable an effective assembly process, the assembly is uniform in a larger area The present invention provides a laser diode and a method of manufacturing the same, which can effectively emit heat to improve the life of the device.

In order to achieve the above object of the present invention, a preferred embodiment includes an N-GaN layer, an N-clad layer, an N-wave guide layer, an active layer, a P-wave guide layer, and a P-clad layer on a substrate. In a laser diode in which P-GaN layers are sequentially stacked, and light is emitted from an active layer by current injected into an N-electrode connected to the N-GaN layer and a P-electrode connected to the P-GaN layer,

The P-GaN layer and the P-clad layer are removed to form a pair of trenches spaced apart from each other.

Ridge is formed between the trenches,

A dielectric film is formed over the trenches and the entire surface of the P-GaN layer to expose a portion of the ridge.

The P-electrode is provided to surround the exposed ridge top surface and a portion of the dielectric film is provided a laser diode.

Another preferred aspect for achieving the above objects of the present invention is a buffer layer, an N-GaN layer, an N-AlGaN cladding layer, an N-GaN waveguide layer, an InGaN active layer, a P-GaN waveguide on the substrate. Sequentially laminating a layer, a P-AlGaN cladding layer and a P-GaN layer;

Removing the P-GaN layer and the P-AlGaN cladding layer to form a pair of trenches spaced apart from each other, and forming a ridge between the trenches;

Mesa etching from the P-AlGaN cladding layer to a portion of the N-GaN layer to expose a portion of the N-GaN layer;

Forming a dielectric film on an entire surface of the ridge to expose a top surface of the ridge and a part of the mesa-etched N-GaN layer;

A method of manufacturing a diode is provided, which includes forming a P-electrode surrounding a portion of the exposed ridge top surface and a dielectric layer and forming an N-electrode surrounding the exposed top surface of the N-GaN layer.

Another preferred aspect for achieving the above objects of the present invention comprises the steps of: growing a laser diode epitaxial structure on a conductive substrate;

Forming a pair of trenches spaced apart from each other in the laser diode epitaxial structure, and forming a ridge between the trenches;

Forming a dielectric film over the entire surface of the ridge to expose the upper surface of the ridge;

A method of manufacturing a laser diode is provided, which includes forming a P-electrode surrounding the exposed ridge top and trenches, and forming an N-electrode on the bottom of the conductive substrate.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

4A to 4E are diagrams illustrating a process of manufacturing a laser diode according to a first embodiment of the present invention. First, as shown in FIG. 4A, a buffer layer 111, an N-GaN layer 112, and an upper portion of the substrate 110 are provided. N-AlGaN cladding layer 113, N-GaN waveguide layer 114, InGaN active layer 115, P-GaN waveguide layer 116, P-AlGaN cladding layer 117 and P-GaN layer 118 ) Are stacked sequentially.

Next, the P-GaN layer 118 and the P-AlGaN cladding layer 117 are removed to form a pair of trenches 121 and 122 spaced apart from each other, and between the trenches 121 and 122. An ridge 125 is formed (FIG. 4B).

Herein, the depths 'd' of the trenches 121 and 122 may satisfy 0.1 μm ≦ d ≦ 5 μm.

6, the trenches 121 and 122 have a rectangular shape, and the width 'W' of the trenches 121 and 122 satisfies 1 μm ≦ W ≦ 500 μm, and the length 'L' 'Satisfies 100 µm ≤ L ≤ 1000 µm.

Subsequently, Mesa is etched from the P-AlGaN cladding layer 117 to a portion of the N-GaN layer 112 to expose a portion of the N-GaN layer 112 (FIG. 4C).

Thereafter, a dielectric film 130 is formed over the entire surface of the ridge 125 to expose the upper surface of the ridge 125 and a part of the mesa-etched N-GaN layer 112 (FIG. 4D).

Finally, the P-electrode 151 is formed to surround the exposed top surface of the ridge 125 and the dielectric layer 130, and the N-electrode 152 surrounding the top surface of the exposed N-GaN layer 112. (Fig. 4e).

5 is a cross-sectional view of a laser diode according to a second embodiment of the present invention, wherein a buffer layer 211, an N-GaN layer 212, an N-AlGaN cladding layer 213, and N− are formed on a conductive substrate 210. A GaN wave guide layer 214, an InGaN active layer 215, a P-GaN wave guide layer 216, a P-AlGaN cladding layer 217, and a P-GaN layer 218 are sequentially stacked; The P-GaN layer 218 and the P-AlGaN cladding layer 217 are removed to form a pair of trenches 221 and 222 spaced apart from each other, and a ridge between the trenches 221 and 222. Ridge) 225 is formed; A dielectric film 230 is formed over the entire surface of the ridge 225 to expose the top surface of the ridge 225; A P-electrode 251 is formed around the exposed ridge 225 and a portion of the dielectric film 230; The N-electrode 252 is formed on the bottom surface of the conductive substrate 210.

Thus, the second embodiment of the present invention grows a laser diode epi structure on a conductive substrate, forms a pair of trenches spaced apart from each other, and forms a ridge inside the trenches. .

Thereafter, a dielectric film is formed on the front surface of the ridge to expose the top surface of the ridge, a P-electrode is formed around the exposed ridge top surface and the trenches, and an N-electrode is formed on the bottom surface of the conductive substrate to manufacture a laser diode. It is.

As described above, the present invention forms trenches on both sides of the ridge to planarize the surface of the laser diode to the same height as the ridge to protect the ridge, thereby preventing mechanical shock and pressure generated during the manufacturing process. Dispersion has the effect of minimizing damage to ridges.

In addition, the ridge can be protected, and the performance and yield of the device can be improved, and an effective assembly process can be enabled.

In addition, assembling is uniformly made over a larger area, it is possible to effectively dissipate heat, thereby improving the life of the device.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

1 is a cross-sectional view showing a schematic structure of a typical blue laser diode

2 is a schematic cross-sectional view showing a state in which a scribing process is performed on a wafer on which a laser diode according to the prior art is manufactured.

3 is a cross-sectional view showing a state in which a laser diode according to the prior art is assembled.

4A to 4E are manufacturing process diagrams of a laser diode according to the first embodiment of the present invention.

5 is a cross-sectional view of a laser diode according to a second embodiment of the present invention.

6 is a schematic top view for explaining the width and length of a trench in accordance with the present invention.

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

110 substrate 111211 buffer layer

112,212: N-GaN layer 113,213: N-AlGaN cladding layer

114,214: N-GaN waveguide layer 115,215: InGaN active layer

116,216 P-GaN wave guide layer 117,217 P-AlGaN cladding layer

118,218 P-GaN layer 121,122,221,222 Trench

125,225: Ridge 151,251: P-electrode

152,252: N-electrode 210: conductive substrate

Claims (6)

An N-GaN layer, an N-clad layer, an N-wave guide layer, an active layer, a P-wave guide layer, a P-clad layer, and a P-GaN layer are sequentially stacked on the substrate and connected to the N-GaN layer. A laser diode in which light is emitted from an active layer by a current injected into an N-electrode and a P-electrode connected to a P-GaN layer, The P-GaN layer and the P-clad layer are removed to form a pair of trenches spaced apart from each other. Ridge is formed between the trenches, A dielectric film is formed over the trenches and the entire surface of the P-GaN layer to expose a portion of the ridge. The P-electrode is formed around the exposed ridge top surface and a portion of the dielectric film laser diode. The method of claim 1, And the depth 'd' of the trenches satisfies 0.1 μm ≦ d ≦ 5 μm. The method according to claim 1 or 2, The width 'W' of the trenches satisfies 1 μm ≦ W ≦ 500 μm, A length 'L' satisfies 100 µm ≤ L ≤ 1000 µm. Sequentially laminating a buffer layer, an N-GaN layer, an N-AlGaN clad layer, an N-GaN wave guide layer, an InGaN active layer, a P-GaN wave guide layer, a P-AlGaN cladding layer, and a P-GaN layer on the substrate; ; Removing the P-GaN layer and the P-AlGaN cladding layer to form a pair of trenches spaced apart from each other, and forming a ridge between the trenches; Mesa etching from the P-AlGaN cladding layer to a portion of the N-GaN layer to expose a portion of the N-GaN layer; Forming a dielectric film on an entire surface of the ridge to expose a top surface of the ridge and a part of the mesa-etched N-GaN layer; Forming a P-electrode surrounding the exposed top surface of the ridge and a portion of the dielectric layer, and forming an N-electrode surrounding the exposed top surface of the N-GaN layer. Growing a laser diode epi structure on the conductive substrate; Forming a pair of trenches spaced apart from each other in the laser diode epitaxial structure, and forming a ridge between the trenches; Forming a dielectric film over the entire surface of the ridge to expose the upper surface of the ridge; Forming a P-electrode surrounding the exposed ridge top surface and the trenches, and forming an N-electrode on the bottom surface of the conductive substrate. The method of claim 5, Growing a laser diode epitaxial structure on the conductive substrate, A buffer layer, an N-GaN layer, an N-AlGaN cladding layer, an N-GaN waveguide layer, an InGaN active layer, a P-GaN waveguide layer, a P-AlGaN cladding layer, and a P-GaN layer are sequentially stacked on the conductive substrate. Method for producing a laser diode, characterized in that.