CN101132111A

CN101132111A - GaN-based blue laser manufacturing method

Info

Publication number: CN101132111A
Application number: CNA2006101125476A
Authority: CN
Inventors: 李慧; 种明
Original assignee: Institute of Semiconductors of CAS
Current assignee: Institute of Semiconductors of CAS
Priority date: 2006-08-23
Filing date: 2006-08-23
Publication date: 2008-02-27

Abstract

A method for manufacturing a gallium nitride-based blue laser, comprising sequentially epitaxially growing a gallium nitride buffer layer, an N-type gallium nitride layer, an N-type cladding layer, an N-type waveguide layer, and multiple quantum wells in an active region on a sapphire substrate layer, P-type waveguide layer, P-type cladding layer, and P-type GaN layer to form a gallium nitride laser structure; etch to form a ridge waveguide; prepare an insulating protective layer and a P-type electrode; prepare a metal cladding layer; Prepare the metal covering layer on the gallium oxide substrate; bond the prepared two samples together, introduce thermally conductive and insulating epoxy resin sealant into the gap, and cure; remove the sapphire substrate; cleavage; after cleavage Coating on the surface of the die cavity; welding the bottom of the gallium arsenide substrate to the heat sink through the solder layer, and leading the P electrode lead and the N electrode lead from the solder layer of the heat sink and the N-type electrode respectively to complete the production of the blue laser .

Description

The manufacture method of gallium nitride based blue laser device

Technical field

The invention belongs to technical field of semiconductors, be meant the manufacture method of gallium nitride based blue laser device especially.

Background technology

GaN base wide-bandgap material is the popular direction of a lot of countries research at present as semiconductive luminescent materials.The GaN based blue laser device especially since its high density storage, dvd system of new generation, laser printing, laser projection and medical aspect application cause people's extensive concern.In actual applications, device is stable most important.The raising of GaN laser calorifics characteristic is most important to realizing the work of device high temperatures.Aspect the GaN laser fabrication, the substrate of growing GaN laser structure employing at present has Sapphire Substrate, SiC substrate and GaN substrate etc.With respect to other substrates, because the Sapphire Substrate low price, so be used widely at present.As substrate but a lot of disadvantageous aspects are arranged with sapphire: one is because its thermal conductivity very low (having only about half of gallium arsenide substrate) causes the heat radiation of GaN laser to become a difficult problem; Its two sapphire and GaN material lattice mismatch are serious, and the lattice plane of the two differs 300, the laser cavity surface that feasible very difficult cleavage goes out to get well.

Summary of the invention

The heat-sinking capability that the manufacture method that the purpose of this invention is to provide a kind of gallium nitride based blue laser device, this method help preparing high-quality laser cavity surface and can effectively improve laser, the performance and the life-span of improving tube core.

The manufacture method of a kind of gallium nitride based blue laser device of the present invention is characterized in that, comprises the steps:

1) on Sapphire Substrate, utilizes metallochemistry organic vapor phase deposition method epitaxial growth of gallium nitride resilient coating, n type gallium nitride layer, N type cover layer, N type ducting layer, active area multiple quantum well layer, P type ducting layer, P type cover layer, P type gallium nitride layer successively, form the gallium nitride laser structure;

2) utilize the method for dry etching, etching P type gallium nitride layer, P type cover layer, P type ducting layer, active area multiple quantum well layer, N type ducting layer and the tectal part of N type both sides etching form ridge waveguide;

3) on the both sides of ridge waveguide and N type cover layer, prepare insulating protective layer;

4) prepare P type electrode at the top of ridge waveguide;

5) upper surface at P type electrode and insulating protective layer prepares metal cladding;

6) get a gallium arsenide substrate, on this gallium arsenide substrate, prepare metal cladding;

7) utilize on-plane surface metal bonding technology that the print that print is inverted and step 6) prepares that step 5) prepares is bonded together, two print metal claddings are closely contacted;

8) gap between two good prints of bonding imports the conduction epoxy resin sealing, and solidifies;

9) remove Sapphire Substrate, expose n type gallium nitride;

10) on n type gallium nitride, make N type electrode;

11) cleavage is divided into singulated dies;

12) the tube core cavity surface film coating after cleavage;

13) by solder layer with gallium arsenide substrate bottom be welded to heat sink on, and respectively from heat sink solder layer and N type electrode draw P contact conductor and N contact conductor, finish the making of blue laser.

Wherein the material of P type electrode is individual layer, alloy or the sandwich construction of Ni, Co, Fe, Cr, Al, Cu, Au, Ti, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os.

Wherein the material of insulating protective layer is SiO2, SiNx, ZrO2 or TiO2.

Wherein the material of metal cladding is Ni, Co, Ti, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os individual layer, alloy or sandwich construction.

Wherein remove Sapphire Substrate in the step 9), concrete grammar is earlier with reducing thin of sapphire substrate, utilize the method for laser scribing to mark the lines groove at the Sapphire Substrate back side, utilize the wet etching liquid of sapphire and gallium nitride then, the Sapphire Substrate of lines trench bottom is eroded fully, then the gallium nitride resilient coating is eroded, thereby Sapphire Substrate is peeled away from gallium nitride epitaxial slice fully by the lines groove.

Wherein the material of N type electrode is Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os individual layer, alloy or sandwich construction.

Wherein the tube core cavity surface film coating after cleavage is meant the anti-anti-film of one side plating at vertical ridge waveguide, another side plating high-reflecting film.

Wherein the material of cavity surface film coating employing is SiO2, SiNx, TiO2 monofilm or multi-layer film structure.

Wherein the material of heat sink employing is oxygen-free copper, tungsten-copper alloy or copper metal.

Description of drawings

In order to further specify technology contents of the present invention, below in conjunction with execution mode and accompanying drawing the present invention is done a detailed description, wherein:

It is the epitaxy junction composition of the GaN base laser of substrate that Fig. 1 represents among the present invention with the sapphire.

Fig. 2 represents the profile behind the preparation gallium nitride laser P district ridge among the present invention.

Fig. 3 represents to have prepared P district ridge among the present invention is profile after the epitaxial wafer of substrate and gallium arsenide substrate are bonded together with the sapphire.

Fig. 4 represents the lines layout that utilizes laser scribing to mark at the Sapphire Substrate quilt cover among the present invention.

Profile after Fig. 5 represents among the present invention Sapphire Substrate removed.

Fig. 6 represents the profile behind the preparation N type electrode among the present invention.

Fig. 7 represents to be welded on the heat sink profile of making gallium nitride based blue laser device of the present invention of going up.

Embodiment

The present invention is a kind of manufacture method of gallium nitride based blue laser device.Its detailed process is as follows:

As shown in Figure 1, on Sapphire Substrate 1, utilize metallochemistry organic vapor phase deposition method epitaxial growth of gallium nitride resilient coating 2a, n type gallium nitride layer 2b, N type cover layer 3, N type ducting layer 4, active area multiple quantum well layer 5, P type ducting layer 6, N type cover layer 7, P type gallium nitride layer 8 successively, form the gallium nitride laser structure.The characteristics of this gallium nitride laser structure are that the defect concentration of gallium nitride resilient coating 2a is much larger than n type gallium nitride layer 2b, so the corrosion rate of gallium nitride resilient coating 2a will be much larger than the corrosion rate of n type gallium nitride layer 2b in gallium nitride wet etching liquid.

At first utilize method etching P type gallium nitride layer, P type cover layer 7, the P type ducting layer 6 of dry etching as shown in Figure 2, form ridge waveguide.Utilize the method for plasma activated chemical vapour deposition (PECVD) etching print surface whole deposition one deck insulating protective layer of ridge waveguide, the insulating protective layer the selection of material is SiO2, SiNx, ZrO2 or TiO2 single or multiple lift structure.Expose the top area of ridge platform then by the method for whirl coating photoetching, wet etching is removed the insulating protective layer of the top area of ridge platform, finally forms insulating protective layer 10, exposes P type gallium nitride layer 8.Utilize the method for electron beam evaporation or magnetron sputtering on the P type gallium nitride layer 8 at ridge platform top, to prepare P type electrode 9, it is individual layer, alloy or sandwich constructions such as Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os that P type electrode adopts material, then P type electrode 9 is carried out under the oxygen atmosphere 500 degree high temperature and scalds fire in order to remove hairs and handle.Utilize the print surface deposition metal cladding 11 of method after finishing above-mentioned steps of electron beam evaporation or magnetron sputtering.It is individual layer, alloy or sandwich constructions such as Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os that metal cladding 11 adopts material.So just form structure as shown in Figure 2.

Other gets a slice gallium arsenide substrate 13, also deposits layer of metal cover layer 11 on its surface, and the employing material is individual layer, alloy or sandwich constructions such as Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os.

To prepare as shown in Figure 3 to be inverted and adopt on-plane surface metal bonding technical key with the gallium arsenide substrate for preparing metal cladding 11 and be in the same place as the print of Fig. 2 structure, key and the time two prints the metal cladding face be faying face, and the alignment edge of two prints that align.The print gap good at bonding imports conduction epoxy resin sealing 12, and carries out cured.Its purpose strengthens the intensity of two print mechanical bond on the one hand, can improve the heat-sinking capability of laser on the other hand.

The Sapphire Substrate 1 of the print that above-mentioned key is become reconciled is removed then, as shown in Figure 5.Concrete grammar is that the Sapphire Substrate 1 of the print of at first above-mentioned key being become reconciled evenly is thinned to about 30um, and the method for utilizing laser scribing is then drawn the lines group of the degree of depth about for 25um at the Sapphire Substrate face according to the lines layout that designs as Fig. 4.Then print is put into molten potassium hydroxide solution, control etching time to Sapphire Substrate is taken out print when print comes off.The detailed process of corrosion is at first to be corroded in the sapphire corrosive liquid, when sapphire is corroded the 5um left and right sides, the sapphire of lines trench bottom is corroded fully to be gone, expose gallium nitride resilient coating 2a, because the defect concentration of gallium nitride resilient coating 2a is much larger than n type gallium nitride layer 2b, so the corrosion rate of gallium nitride resilient coating 2a will be much larger than the corrosion rate of n type gallium nitride layer 2b in gallium nitride wet etching liquid.Like this, corrosive liquid sees through the lines groove rapidly with gallium nitride resilient coating 2a undercutting, thereby Sapphire Substrate is peeled off from print, and sapphire takes out print once coming off from corrosive liquid.This moment, n type gallium nitride layer 2b was exposed to outermost layer, and the single die cross section as shown in Figure 5;

Then make N type electrode 15 as shown in Figure 6 on n type gallium nitride layer 2b, it is individual layer, alloy or sandwich constructions such as Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os that N type electrode adopts material.Having made N type electrode 15 back cleavage prints is singulated dies, and with the tube core cavity surface film coating, at the anti-anti-film of one side plating of vertical ridge waveguide, another side plating high-reflecting film, the material that cavity surface film coating adopts is SiO2, SiNx, TiO2 monofilm or multi-layer film structure.

Behind the tube core cavity surface film coating, its gallium arsenide substrate 13 is welded on heat sink 16 by solder layer 14, and draws P type contact conductor 17 and N type contact conductor 18 respectively, form a complete tube core with good heat conductive performance, its cross section as shown in Figure 7.

The present invention is a kind of manufacture method of gallium nitride based blue laser device, after having prepared ridge waveguide, by on-plane surface metal bonding technology the gallium nitride epitaxial slice height entirely is bonded on the gallium arsenide substrate 13, can realize like this Sapphire Substrate evenly being thinned to very thin degree (30um), utilize the method for laser scribing and wet etching that Sapphire Substrate is removed then by mechanical lapping.The substrate of so successfully realizing the gallium nitride laser switches to gallium arsenide substrate by Sapphire Substrate.The characteristics sapphire removal method easy realization low for equipment requirements of this method.Traditional make substrate with sapphire and make gallium nitride based blue laser device a lot of disadvantageous aspects are arranged: one is because its thermal conductivity very low (having only about half of gallium arsenide substrate) causes the heat radiation of GaN laser to become a difficult problem; Its two sapphire and GaN material lattice mismatch are serious, and the lattice plane of the two differs 300, the laser cavity surface that feasible very difficult cleavage goes out to get well.And after realizing that substrate switches to gallium arsenide substrate, cleavage direction according to GaAs can be obtained high-quality laser cavity surface easily, while is owing to the ridge waveguide district that the laser heat mainly produces the district combines by metal and gallium arsenide substrate, heat can by the much better gallium arsenide substrate of thermal conductivity lead heat sink on, distribute, thermal characteristics is greatly enhanced like this, thereby has improved the performance of laser greatly.

Claims

1. A fabrication method of gallium nitride-based blue light laser, is characterized in that, comprises the steps:

1) On the sapphire substrate, epitaxially grow GaN buffer layer, N-type GaN layer, N-type cladding layer, N-type waveguide layer, multi-quantum well layer in active region, P-type A waveguide layer, a P-type cladding layer, and a P-type GaN layer form a GaN laser structure;

2) Etching the P-type gallium nitride layer, P-type cladding layer, P-type waveguide layer, active region multi-quantum well layer, N-type waveguide layer and both sides of the N-type cladding layer by dry etching Etching to form a ridge waveguide;

3) Prepare an insulating protective layer on both sides of the ridge waveguide and on the N-type cladding layer;

4) Prepare a P-type electrode on the top of the ridge waveguide;

5) preparing a metal covering layer on the upper surface of the P-type electrode and the insulating protective layer;

6) taking a gallium arsenide substrate, and preparing a metal covering layer on the gallium arsenide substrate;

7) Using the non-planar metal bonding technique to invert the sample prepared in step 5) and bond the sample prepared in step 6) together, so that the metal covering layers of the two samples are in close contact;

8) Introduce thermally conductive and insulating epoxy resin sealant in the gap between the bonded two samples, and cure;

9) Remove the sapphire substrate to expose N-type gallium nitride;

10) Fabricate N-type electrodes on N-type gallium nitride;

11) cleavage, split into individual tube cores;

12) Coating on the cavity surface of the tube core after cleavage;

13) Weld the bottom of the gallium arsenide substrate to the heat sink through the solder layer, and lead out the P electrode lead and the N electrode lead from the solder layer of the heat sink and the N-type electrode respectively to complete the production of the blue laser.

2. the manufacture method of GaN-based blue light laser according to claim 1, is characterized in that, wherein the material of P-type electrode is Ni, Co, Fe, Cr, Al, Cu, Au, Ti, W, Mo, Single layer, alloy or multilayer structure of Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os.

3. The fabrication method of GaN-based blue laser according to claim 1, wherein the material of the insulating protection layer is SiO2, SiNx, ZrO2 or TiO2.

4. The fabrication method of GaN-based blue light laser according to claim 1, wherein the material of the metal coating is Ni, Co, Ti, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os single layer, alloy or multilayer structure.

5. the manufacture method of gallium nitride-based blue light laser according to claim 1 is characterized in that, wherein step 9) removes sapphire substrate, and concrete method is to thin sapphire substrate earlier, utilizes laser scribing The method draws line grooves on the back of the sapphire substrate, and then uses the wet etching solution of sapphire and gallium nitride to completely etch the sapphire substrate at the bottom of the line grooves, and then etches the gallium nitride buffer layer through the line grooves, thereby The sapphire substrate was completely peeled off from the GaN epitaxial wafer.

6. The manufacturing method of GaN-based blue light laser according to claim 1, wherein the material of the N-type electrode is Ni, Co, Fe, Cr, Al, Cu, Au, W, Mo, Ta, Ag, Pt, Pd, Rh, Ir, Ru, Os single layer, alloy or multilayer structure.

7. the manufacture method of gallium nitride-based blue light laser according to claim 1 is characterized in that, wherein in the tube core cavity surface coating film after cleavage, refers to coating anti-reflection coating on one side of vertical ridge waveguide, another One side is coated with high reflective film.

8 . The method for manufacturing a GaN-based blue laser according to claim 7 , wherein the material used for the cavity surface coating is SiO2, SiNx, TiO2 single-film or multi-layer film structure.

9 . The method for manufacturing a GaN-based blue laser according to claim 1 , wherein the heat sink is made of oxygen-free copper, tungsten-copper alloy, or copper metal.