CN101514484B

CN101514484B - Porous material substrate used in GaN film grown by HVPE method and method thereof

Info

Publication number: CN101514484B
Application number: CN200910046387A
Authority: CN
Inventors: 于广辉; 王新中; 林朝通; 曹明霞; 卢海峰; 李晓良; 巩航; 齐鸣; 李爱珍
Original assignee: DAHOM (FUJIAN) ILLUMINATION TECHNOLOGY Co Ltd
Current assignee: Dahom (Fujian) Illumination Technology Co., Ltd.
Priority date: 2009-02-20
Filing date: 2009-02-20
Publication date: 2012-08-29
Anticipated expiration: 2029-02-20
Also published as: CN101514484A

Abstract

The invention relates to a nano-porous material substrate used in hydride vapor phase epitaxy (HVPE) gallium nitride (GaN) film and a preparation method thereof. The invention is characterized in that composite nano-porous material is taken as a substrate for epitaxially growth of a thick film GaN, and the quality of crystalloid can be improved, meanwhile, the substrate can be conveniently stripped. A metal Al thin layer is firstly sedimentated on a GaN template taking Si as the substrate, even porous meshed anodic aluminum oxide (AAO) is formed by an electrochemic method, porous GaN material is obtained by erosion of technologies such as induced coupling plasma etching (ICP) and the like, and the bottom of the holes are exposed outside the surface of the Si substrate; on this basis, a corrosion method is adopted to realize the corrosion for Si and obtain the composite nano-porous structure; by the superficial treatment, the Si is covered with a SiNx layer or SiO2 layer, so as to meet the requirements of subsequent epitaxial growth. After being washed, the product is put into an HVPE system, and the thick film GaN layer grows. The invention greatly simplifies the technique for manufacturing a mask film by photoetching, and is suitable for scientific experiments and batch production.

Description

Porous material substrate and the method used in the HVPE method GaN film grown

Technical field

The present invention relates to silica-based composite Nano porous material substrate that uses in a kind of hydride gas-phase epitaxy (HVPE) method growing gallium nitride (GaN) film and preparation method thereof.Be intended to improve the epitaxial growth GaN quality of materials, make things convenient for peeling off of substrate, belong to technical field of material.

Background technology

HVPE is one of conventional means of growing GaN epitaxial material; Have the advantages that equipment is simple, cheap, growth velocity is high; Therefore at direct growth GaN single crystal material very under the situation of difficult; Utilizing the advantage of HVPE on foreign substrate, to grow high-quality thick film GaN epitaxial film, peel off with foreign substrate then, is a good approach that obtains GaN intrinsic substrate.

As the singularity of substrate applications require in the epitaxial material defect concentration particularly the density of line dislocation will be low and distribute and want evenly, the stress in the material is as far as possible little simultaneously, the device quality of otherwise on such substrate, growing just is difficult to ensure.Adopted certain methods to reduce the dislocation in the extension GaN film in order to address this problem people; Improve the quality of GaN film; Comprising horizontal extension outgrowth (ELOG) technology, growth interruption technology etc., but the GaN dislocation desity skewness that conventional ELOG method grows out.In addition; Owing to have bigger lattice mismatch and thermal mismatching between substrate material that adopts at present and the GaN; When surpassing certain thickness, the GaN growth also will crack at the interface; And along with the increase crackle of thickness also can spread to the surface, this very serious problem especially in the growth of thick film GaN.People had once adopted porous Si and porous SiC as substrate; Utilize its cavernous structure to hold the recoverable strain that produces in the hetero epitaxy; Also reduced the dislocation desity in the GaN epitaxial film to a certain extent; The nanoscale porous is evenly distributed simultaneously, the ununiformity of having avoided traditional ELOG technology to produce.

Nearest 2 years, external researchist adopted porous GaN film as substrate, utilized MOX vapour phase epitaxy (MOCVD) epitaxy high quality GaN epitaxial film.It is the thick film GaN material HVPE epitaxy of substrate that the present inventor has also carried out with the nanoporous GaN on the sapphire, has realized the selective epitaxy growth of microcell air bridges mode, improves the quality of thick film GaN, reduces the stress in the material simultaneously.But because the growth velocity of HVPE is very fast, the restriction of this method be after the HVPE epitaxy Sapphire Substrate peel off still difficulty, be difficult to simultaneously as MOCVD still can be complete after growth retain the cavity among the nanometer GaN.

How when improving the epitaxial material quality, can realize that again it is the problem that presses for solution that substrate is peeled off easily.The present invention intends the design that has proposed a kind of composite Nano porous substrate for this reason, and it is on the basis of silica-based GaN film, the preparation nano-porous structure, and the GaN film is passed in the hole, and extends in the Si substrate, through handling, makes the Si that exposes become SiN simultaneously _xPerhaps SiO ₂, we are called composite nano-porous structure.A kind of structure had so both been utilized the microcell selective epitaxy growth characteristics of GaN template, thereby improved the epitaxial quality of HVPE growth, simultaneously the SiN or the SiO of internal surface of hole ₂Layer can effectively suppress the crystallization of GaN, thereby has guaranteed the reservation in space; The Si substrate can adopt the method for chemistry to remove in addition, has realized peeling off of substrate at an easy rate.This shows, compare that this silica-based composite Nano porous substrat structure is more suitable for the growth in the HVPE of thick film GaN with general nano-porous materials.

Summary of the invention

The object of the present invention is to provide the porous material substrate and the preparation method that use in a kind of hydride gas-phase epitaxy (HVPE) method GaN film grown.

Described porous material substrate is SiN or the SiO that forms on the silicon substrate ₂Silica-based composite nano-porous structure;

Described composite Nano porous material substrate is to obtain through Grown GaN epitaxial film on the processing Si substrate;

Described composite Nano porous material substrate is to be mould with the porous anodic aluminium oxide, utilizes the method for ICP etching to process cavernous; Peeling off through chemical corrosion of Si substrate realizes.

Specifically; Prepare in the process of GaN film at HVPE; The growth of GaN adopts Si as substrate, and the making step that silica-based composite Nano is controlled material more is: the GaN epitaxial film that 1. at first adopts one 0.1～100 micron of HVPE, metal organic chemical vapor deposition (MOCVD) or the growth of molecular beam epitaxy (MBE) method is as template, 2. after electron beam evaporation layer of metal aluminium (Al) thin layer; Thickness is about 50nm～10 μ m; 3. be placed in oxalic acid (0.3mol/L) or sulfuric acid (15wt%) solution after and carry out galvanic corrosion, the mixing solutions of 4. putting into phosphoric acid (5wt%) or phosphoric acid (6wt%) and chromic acid (1.8wt%) again soaks mesh structural porous anodised aluminium (AAO) mask that has just formed rule, 5. and then through the ICP etching; Let nanoporous extend to the Si substrate interior, make the bottom in hole expose the Si substrate surface; 6. adopt corrosion or electrochemical method, realize corrosion and acquisition composite nano-porous structure Si; 7. through surface treatment, make surface coverage SiN or the SiO of Si ₂Layer is to satisfy requirements of subsequent epitaxial growth.Next remove residual A AO mask with acid solution, after cleaning, put into HVPE system growth thick film GaN layer again.Then template is placed HVPE equipment growing GaN, anneal gas is N ₂, H ₂Perhaps both mixed gass.A kind of structure had so both been utilized the microcell selective epitaxy growth characteristics of GaN template, thereby improved the epitaxial quality of HVPE growth, simultaneously the SiN or the SiO of internal surface of hole ₂Layer can effectively suppress the crystallization of GaN, thereby has guaranteed the reservation in space; The Si substrate can adopt the method for chemistry to remove in addition, has realized peeling off of substrate at an easy rate.This shows, compare that this composite Nano porous substrat structure is more suitable for the growth in the HVPE of thick film GaN with general nano-porous materials.This method is simple; Only need adopt electrochemical method corrosion to be deposited on the metal Al layer of GaN template surface; Promptly can be made into the substrate that the composite Nano porous material is used as the GaN extension through the ICP etching; Peeling off through chemical corrosion of Si substrate realizes, simplified the technology of photoetching making mask greatly, adopts when being suitable for scientific experiment and producing in batches.

As stated, present method adopts the composite Nano porous material as the substrate epitaxial growth GaN material, and its advantage is summarized as follows:

1. adopt silica-based composite Nano porous material substrate, realized the microcell horizontal extension outgrowth of material, discharged the epitaxial film internal stress greatly, reduced dislocation desity simultaneously, improved crystal mass;

2. the nanoporous that forms is even, and the distribution in the size in hole and aperture also can be regulated with the need;

3. because as composite Nano porous material substrate even aperture distribution, therefore dislocation is evenly distributed in HVPE Grown GaN epitaxial film, improved the utilizability of the GaN after the growth;

4. the GaN outer layer growth method as template can adopt several different methods preparations such as gas phase epitaxy of metal organic compound (MOCVD) or molecular beam epitaxy (MBE) method;

5.Si peeling off of substrate can easily realize through chemical corrosion.

Description of drawings

Fig. 1 is the thick film GaN structural representation on the silica-based composite Nano porous substrate provided by the invention

Among the figure, 1.Si substrate 2.SiN _xPerhaps SiO ₂ Layer 3. space 4.MOCVD-GaN 5.HVPE-GaN

Embodiment

One deck GaN film on the Si substrate, grow earlier as template; On template, adopt the method for electron beam evaporation to deposit the thick metal Al thin layer of about 1 μ m then; Put into oxalic acid solution (0.3mol/L) to the template of the thin layer that has metal A l again; At room temperature adopt 40 volts voltage to carry out anodic oxidation 40min, and then in phosphoric acid solution (5wt%), soak 30min to template and remove that part of aluminum oxide that the aperture bottom contacts with the GaN of lower floor, adopt dry etching technologies such as ICP again; Etching obtains porous GaN material, makes the bottom in hole expose the Si substrate surface; Adopt corrosion or electrochemical method on this basis, realize corrosion and acquisition composite nano-porous structure Si; Then through surface treatment, make the surface coverage SiN of Si _xPerhaps SiO ₂Layer is to satisfy requirements of subsequent epitaxial growth; Next remove residual A AO mask with acid solution, after cleaning, template is put into the hvpe reactor chamber, at N ₂Be warming up to 800 ℃ in the atmosphere, logical NH ₃The GaN layer of protection template begins logical HCl and grows in the time of 1050 ℃, obtain thick film GaN.Through the method for chemical corrosion, carry out peeling off of Si substrate at last.

Claims

1. the preparation method of the porous material substrate that uses in the HVPE method GaN film grown is characterized in that making step is:

(1) with Si is substrate, grows one deck GaN epitaxial film above that as template earlier;

(2) on the template of GaN epitaxial film, deposition layer of metal Al film, the Al film thickness is 50nm-1 μ m;

(3) place oxalic acid or sulphuric acid soln to adopt electrochemical method to be oxidized to uniform porous anodic aluminium oxide to Al template;

(4) template being put into phosphoric acid or phosphoric acid and the mixing solutions of chromic acid soaks to remove that part of aluminum oxide that the aperture bottom contacts with the GaN of lower floor and the mesh structural porous anodised aluminium mask of formation rule;

(5) coupled plasma etching dry etching technology is induced in employing, and etching obtains porous GaN material, makes nanoporous extend to the Si substrate interior, makes the bottom in hole expose the Si substrate surface;

(6) adopt corroding method, realize corrosion and acquisition composite nano-porous structure Si;

(7), make surface coverage SiN or the SiO of Si through surface treatment ₂Layer is to satisfy requirements of subsequent epitaxial growth.

2. by the described preparation method of claim 1; It is characterized in that on the Si substrate; Growth is adopted in HVPE, metal organic chemical vapor deposition or the molecular beam epitaxial method any one as the GaN epitaxial film of template, and the Grown GaN epitaxy layer thickness is the 0.1-100 micron.

3. by the described preparation method of claim 1, it is characterized in that metal A l thin film deposition adopts electron beam evaporation or sputtering method to prepare on the GaN epitaxial film.

4. by the described preparation method of claim 1; It is characterized in that it is to adopt electrochemical method to implement that metal A l film changes uniform porous anodic aluminium oxide into, described electrochemical method is that the Al film is placed oxalic acid solution or the mass percentage concentration of 0.3mol/L concentration is 15% sulphuric acid soln.

5. by the described preparation method of claim 1; The solution that it is characterized in that removing the mesh structural porous anodised aluminium mask employing of that part of aluminum oxide that the aperture bottom contacts with the GaN of lower floor and formation rule is the mixing solutions of phosphoric acid solution or phosphoric acid and chromic acid; Wherein the mass percentage concentration of phosphoric acid solution is 5%; The mass percentage concentration of phosphoric acid is 6% in the mixing solutions of phosphoric acid and chromic acid, and the mass percentage concentration of chromic acid is 1.8%.

6. by the described preparation method of claim 1, it is characterized in that step 6 adopts electrochemical method, realize corrosion and acquisition composite nano-porous structure Si.

7. the porous material substrate that uses in the HVPE method Grown GaN film that obtains by the preparation method of each described porous material substrate among the claim 1-5 is characterized in that described porous material substrate is SiN or the SiO that forms on the silicon substrate ₂Silica-based composite nano-porous structure.

8. the porous material substrate stated of claim 7 is characterized in that described porous material substrate obtains through Grown GaN epitaxial film on the processing Si substrate.

9. the porous material substrate of stating by claim 7 is characterized in that silica-based compound porous structure is is mask with the porous anodic aluminium oxide, with inducing the method for coupled plasma etching to process cell texture.