CN1176483C

CN1176483C - Process for preparing self-supporting gallium nitride substrate by laser stripping method

Info

Publication number: CN1176483C
Application number: CNB02113085XA
Authority: CN
Inventors: 荣张; 张�荣; 修向前; 徐剑; 顾书林; 卢佃清; 毕朝霞; 沈波; 刘治国; 江若琏; 施毅; 朱顺明; 韩平; 胡立群
Original assignee: Nanjing University
Current assignee: Nanjing University
Priority date: 2002-05-31
Filing date: 2002-05-31
Publication date: 2004-11-17
Anticipated expiration: 2022-05-31
Also published as: CN1383185A

Abstract

The present invention relates to a method for preparing a self support gallium nitride substrate by laser stripping. An excimer laser is adopted. The energy corresponding to a laser wavelength is smaller than the band gap energy of sapphire, but larger than the band gap energy of GaN. The laser irradiation penetrates a sapphire substrate and irradiates GaN at a sapphire-gallium nitride interface; afterwards, the heating or the weak acid corrosion is carried out; the GaN is separated from the sapphire, and a GaN self support substrate is obtained; particularly, a gallium nitride surface is firstly stuck on a base sheet, and then, the laser irradiation is carried out; after the GaN is separated from the sapphire, base sheet bonding layers are separated by a heating method.

Description

Laser lift-off prepares the method for self-standing gan substrate

One, technical field

The present invention relates to adopt laser lift-off technique stripping gallium nitride (GaN) on the Sapphire Substrate to obtain the method and the technology of free from flaw self-supporting GaN substrate.

Two, technical background

III-V group nitride material (claiming the GaN sill again) based on GaN and InGaN, AlGaN alloy material is the novel semiconductor material of extremely paying attention in the world in recent years, the direct band gap of its 1.9-6.2eV continuous variable, excellent physics, chemical stability, high saturated electron drift velocity, superior functions such as high disruptive field intensity and high heat conductance make it become the most preferably material of short wavelength's semiconductor photoelectronic device and high frequency, high pressure, the preparation of high temperature microelectronic component.

Because the restriction of the physical property of GaN own, the growth of GaN body monocrystalline has very big difficulty, as yet practicability not.Yet, carry out homoepitaxy with the GaN substrate and obtain III group-III nitride thin-film material and but demonstrated extremely superior performance, therefore with the low-dislocation-density substrate carry out GaN homoepitaxy be improve III nitride epitaxial layers quality than good method.

At present, large tracts of land GaN substrate all is to go up vapor phase growth GaN thick film in foreign substrate (as sapphire, SiC, Si etc.) usually, obtains after then former foreign substrate being separated.Wherein growing GaN is the most general on Sapphire Substrate, and quality is also the highest.In order to obtain self-supporting GaN substrate, must remove Sapphire Substrate.Because sapphire is extremely stable, is difficult to adopt chemical corrosion method.General method is a mechanical grinding, but because of sapphire is very hard, not only will consume a large amount of diamond abrasives, and cost is very high and speed is extremely slow.Adopt the method for laser irradiation, utilize laser that the boundary zone heating of GaN thick film and substrate is made it fusing, thereby obtain the GaN substrate of self-supporting.The advantage of laser-stripping method is that the time is fast, and Sapphire Substrate is recyclable.

In the present invention, we adopt the laser scanning irradiation technique, on Sapphire Substrate the GaN film are stripped down, and obtain self-supporting free from flaw GaN substrate.

Three, technology contents

The present invention seeks to: with the laser scanning irradiation technique GaN film is stripped down from Sapphire Substrate, obtain free from flaw self-supporting GaN substrate.

Technical solution of the present invention is: the method that adopts laser irradiation, utilize laser to see through Sapphire Substrate and make at the interface to the heating of the boundary zone of GaN thick film and Sapphire Substrate that GaN decomposes, be higher than heating or weak hcl corrosion more than the Ga fusing point, just GaN and sapphire can be separated, thus the GaN substrate of acquisition self-supporting.

Further improvement of the present invention is: earlier gallium nitride surface is bonded on the substrate, as substrate, carries out laser irradiation as silicon chip again, after GaN and sapphire are separated, with heating means the substrate adhesive linkage is separated again.

Mechanism of the present invention and technical characterstic are:

The pairing energy of optical maser wavelength is less than the sapphire band-gap energy in laser lift-off technique, but greater than the band-gap energy of GaN.When the laser penetration Sapphire Substrate arrived sapphire/GaN interface, GaN absorbed its energy, and following decomposition takes place.

Being higher than heating or weak hcl corrosion more than the Ga fusing point, just GaN and sapphire can be separated, thereby obtain GaN self-supporting substrate.

Four, description of drawings

Fig. 1 is the present invention's laser lift-off GaN technology schematic diagram on the Sapphire Substrate

Fig. 2 for sapphire-GaN in the laser lift-off process of the present invention at the interface pressure produce schematic diagram, Sappire is a sapphire.

Five, embodiment

The present invention program mainly comprises following step:

1, adopts gas phase epitaxy of metal organic compound (MOCVD), molecular beam epitaxy (MBE), hydride gas-phase epitaxy (HVPE) or additive method growing GaN film on Sapphire Substrate.

2, make backing material with Si (111).Silicon wafer is attached on the GaN, forms sapphire/GaN/Si structure.

3, select suitable laser, sapphire is passed in the laser vertical incident that will have certain energy density, irradiation sapphire/GaN interface.The pairing energy of optical maser wavelength is less than the sapphire band-gap energy, but greater than the band-gap energy of GaN.As adopting Lambda Physik LPX 205i KrF ultraviolet light excimer laser (wavelength 248nm, the wide 38ns of pulse), laser energy density is from 200～5000mJ/cm ²Change.

4, in the following heating sapphire/GaN/Si structure of the temperature that is higher than metal Ga (29 ℃), or with weak HCl solution corrosion sapphire/GaN metal at the interface, Sapphire Substrate just can be stripped from.Obtain the GaN/Si structure.

5,500 ℃ are heated the GaN/Si structures, or the GaN/Si structure is put into suitable organic solvent, and silicon chip is removed.Can obtain self-supporting GaN substrate.

Utilize the laser irradiation lift-off technology, we have successfully obtained free from flaw self-supporting GaN substrate.Before and after laser lift-off, not bigger variation such as the structure of GaN and optical property.Carefully control the laser lift-off condition, we can realize the peeling off of GaN film of large tracts of land (diameter＞2 inch).

Claims

1, laser lift-off prepares the method for self-standing gan substrate, it is characterized in that earlier gallium nitride surface being bonded on the substrate, carry out laser irradiation again, after GaN and sapphire separated, with heating means the substrate adhesive linkage is separated again, institute's employing excimer laser such as following: the pairing energy of optical maser wavelength is less than the sapphire band-gap energy, but band-gap energy greater than GaN, laser irradiation sees through Sapphire Substrate, irradiation sapphire-gallium nitride GaN at the interface, GaN and sapphire are separated in heating or weak acid corrosion then, obtain GaN self-supporting substrate.