CN101369529A

CN101369529A - Method for preparing flawless nitride semiconductor underlay

Info

Publication number: CN101369529A
Application number: CNA2008101676228A
Authority: CN
Inventors: 徐永宽; 于祥潞; 程红娟; 杨巍; 赖占平; 严如岳
Original assignee: CETC 46 Research Institute
Current assignee: CETC 46 Research Institute
Priority date: 2008-10-21
Filing date: 2008-10-21
Publication date: 2009-02-18

Abstract

The invention discloses a method for effectively preparing a flawless nitride semiconductor substrate with low cost, the method comprises A. adhering sapphire or silicon or the like foreign substrates on the steady sapphire or silicon or the like substrates under high temperature without causing pollution to the nitride; B. thinning and polishing the foreign substrates enabling the thickness to be of 5-150 mu m; C. growing a layer of nitrides which are thicker than the foreign substrates on the foreign substrates adopting HVPE method, MOCVD method or MBE method, wherein, the thickness of the nitride layer is best more than three times of the thickness of the foreign substrates; D. cooling down after the nitrides are grown, wherein the foreign substrates generally smash and break, going on to remove residual foreign substrates on the nitrides layer to obtain the nitride layer as the nitride semiconductor substrate.

Description

A kind of method for preparing the flawless nitride semiconductor substrate

Technical field

The invention belongs to the nitride-based semiconductor technical field, relate in particular to a kind of method for preparing the flawless nitride semiconductor substrate.

Background technology

In recent years, the wide bandgap compound semiconductor gallium nitride becomes one of semi-conducting material that receives much concern in the world with its excellent physics and chemical property.Devices such as the LED of GaN base, LD, HBT, HEMT have obtained using widely, especially blue light and white light LEDs rely on advantages such as low-power consumption, high brightness, life-span be long, pollution-free to become the new lover in semiconductor lighting and demonstration field, have catered to the modern widely and have praised highly environmental protection, requirements of saving energy.

Owing to lack homo-substrate, GaN, III-V compound semiconductors such as AlN are at sapphire for a long time, SiC, Si, grow on the foreign substrate such as GaAs, and GaN, exist the mismatch of bigger lattice mismatch and thermal coefficient of expansion between III-V compound semiconductors such as AlN and the foreign substrate, make epitaxial crystal produce a large amount of dislocations and micro-crack, these have had a strong impact on the quality of crystal, and then influenced GaN, so the performance of III-V compound semiconductor base devices such as AlN is GaN, the acquisition of III-V compound semiconductor homo-substrate such as AlN just becomes the solution crystal mass and improves the device performance effective way.

HVPE method (Hydride Vapor Phase Epitaxy, hydride vapour phase epitaxy method) becomes the method for optimizing of volume production nitride with higher growth rate and lower equipment cost, adopt HVPE method growth thickness on foreign substrate to surpass 200 microns nitride, then foreign substrate is removed, just obtained the self-supporting nitride.But, because thermal mismatching causes very big thermal stress, often cause bending even cracking during cooling because this nitride layer is still on foreign substrate and grows.People adopt and to add resilient coating, metal level and make method such as figure mask between nitride layer and foreign substrate for this reason, this can discharge stress to a certain extent, but program is often too complicated, and the corollary equipment that needs is comparatively expensive, cost is higher, has influenced volume production.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of with low cost and effectively prepare the method for flawless nitride semiconductor substrate.

For solving the problems of the technologies described above, the inventive method comprises the steps:

Steps A, foreign substrate is adhered in the substrate at high temperature stable and that can not pollute nitride, and with the THICKNESS CONTROL of described foreign substrate between 1～200 micron;

Step B, the one deck of growing on described foreign substrate are than the remarkable thicker nitride of this foreign substrate, and the thickness of this nitride layer is more than three times of foreign substrate thickness preferably;

Like this, because described foreign substrate is very thin, and nitride layer is significantly thick than foreign substrate, thereby when nitride growth finishes the back cooling, and thermal stress causes breaks and often occur on this foreign substrate rather than on the nitride layer;

Step C, finish the back cooling in nitride growth, comminuted breaking takes place in then described foreign substrate usually, again foreign substrate residual on the nitride layer is removed, with the nitride layer that obtains as the nitride-based semiconductor substrate.

In the steps A, described foreign substrate can be to adopt the mode of low melting point flexible metal pressure welding to adhere to described suprabasil.

Described foreign substrate can be sapphire or silicon.

Described substrate can be sapphire or silicon.

In the steps A, the thickness of described foreign substrate preferably is controlled between 5～150 microns.

The method of the described control foreign substrate of steps A thickness is specifically as follows: after adhering to described foreign substrate in the described substrate, with this foreign substrate attenuate.This method specifically can also for: before described foreign substrate is adhered to described substrate, on another supporter with described foreign substrate attenuate.

In step B, the method for growing nitride can be the HVPE method, also can be metal-organic chemical vapor deposition equipment method or molecular number epitaxy.

Beneficial effect of the present invention is:

In the inventive method, because foreign substrate thickness has been reduced to very little, the nitride thickness that growth obtains is the several times of foreign substrate thickness, and it is bonding between substrate and the substrate by the flexible metal, like this behind growth ending in the temperature-fall period, the thermal stress undercapacity that foreign substrate produces is to destroy nitride layer, and breaking often occurs in foreign substrate, and nitride layer remains intact.The present invention is with respect to adding resilient coating, metal level and making method such as figure mask between nitride layer and foreign substrate, cost is significantly lower, and it implements simply, helps realizing volume production nitride-based semiconductor substrate.

Description of drawings

Fig. 1 arrives the substrate schematic diagram with foreign substrate with metal adhesion;

Fig. 2 is with the schematic diagram behind the foreign substrate attenuate;

Fig. 3 is the schematic diagram after grown nitride layer on the foreign substrate.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

In order to obtain flawless GaN, nitride thick films such as AlN, the inventive method need be with sapphire, Si, GaAs, SiC, foreign substrate such as LiAlO2 are thinned to certain thickness, but because a little less than the thin foreign substrate self-supporting ability, easily bend and break, so select for use low-melting-point metal that this foreign substrate is sticked to sapphire, in the down stable and substrate that can not pollute thick film of high temperature such as Si, the low-melting-point metal of selecting for use is specifically as follows Au, Al, Cu, In, Sn etc., and then with the foreign substrate attenuated polishing to suitable thickness, be generally 1～200 micron, preferably 5～150 microns.Utilize HVPE method, mocvd method (metal-organic chemical vapor deposition equipment method) or MBE method methods such as (molecular number epitaxys) again, thick films such as growing GaN, AlN on the foreign substrate of attenuate.

Because sapphire, Si, GaAs, foreign substrate thickness such as SiC, LiAlO2 have been reduced to very little, GaN, AlN equal thickness that growth obtains are the several times of foreign substrate thickness, and it is bonding between foreign substrate and the substrate by the flexible metal, so in temperature-fall period, the thermal stress undercapacity that foreign substrate such as sapphire, Si, GaAs, SiC, LiAlO2 produce is to destroy nitride layer, breaking often occurs in foreign substrate, and nitride layer remains intact.

Behind the thick films such as growing GaN, AlN, InN, continue foreign substrate rubbing downs such as remaining sapphire, Si, GaAs, SiC, LiAlO2 to be fallen or erode, promptly obtain the substrates such as GaN, AlN of self-supporting.

Below with the example that is prepared as of gallium nitride self-supporting substrate, technology of the inventive method etc. is described further, in this embodiment, the inventive method specifically comprises the steps:

Step 1, with each sputter layer of metal In of two sapphires, fusion is bonded together, as shown in Figure 1,1 for as the sapphire of foreign substrate among the figure, 2 are the sapphire as substrate, 3 is metal In;

A slice in step 2, two sapphires that will bond together is polished after being thinned to 100 μ m with the method for mechanical polishing, and cleans, and does foreign substrate with this sheet sapphire, as shown in Figure 2;

Step 3, the Sapphire Substrate behind the attenuate is put into the HVPE epitaxial furnace together with the sapphire substrates that bonds together with it, be warming up to 1000～1080 ℃, growth thickness is the GaN single crystal film of three times of Sapphire Substrate thickness, and as shown in Figure 3,4 is the GaN single crystal film among this figure.

Lower the temperature behind step 4, the growth ending, comminuted breaking can take place in Sapphire Substrate, and the preservation of GaN layer is complete.Remaining Sapphire Substrate grinding and polishing is fallen in continuation, promptly obtains the GaN substrate of self-supporting.

Above-described specific embodiment, purpose of the present invention, technical scheme and beneficial effect are further described, institute it should be noted, the above only is specific embodiments of the invention, and those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of the technical scheme of claim record of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims

1. a method for preparing the flawless nitride semiconductor substrate is characterized in that comprising the steps:

Step B, the one deck of growing on described foreign substrate are than the remarkable thicker nitride of this foreign substrate;

Step C, cooling after nitride growth finishes, and still residual foreign substrate is removed on the back nitride layer of will lowering the temperature.

2. the method for preparing the flawless nitride semiconductor substrate according to claim 1 is characterized in that:

In the steps A, described foreign substrate is to adopt the low melting point flexible metal to be bonded to described suprabasil.

3. the method for preparing the flawless nitride semiconductor substrate according to claim 1 is characterized in that:

Described foreign substrate is a sapphire.

4. the method for preparing the flawless nitride semiconductor substrate according to claim 1 is characterized in that:

Described substrate is a sapphire.

5. according to each described method for preparing the flawless nitride semiconductor substrate in the claim 1 to 4, it is characterized in that:

In the steps A, the thickness of described foreign substrate is between 5～150 microns.

6. according to the method for preparing the flawless nitride semiconductor substrate described in the claim 5, it is characterized in that:

In step B, the thickness of described nitride layer is more than three times of described foreign substrate thickness.

7. according to each described method for preparing the flawless nitride semiconductor substrate in the claim 1 to 4, it is characterized in that:

8. according to each described method for preparing the flawless nitride semiconductor substrate in the claim 1 to 4, it is characterized in that:

The method of the described control foreign substrate of steps A thickness is: after adhering to described foreign substrate in the described substrate, with this foreign substrate attenuate.

9. according to each described method for preparing the flawless nitride semiconductor substrate in the claim 1 to 4, it is characterized in that:

In step B, the method for growing nitride is the HVPE method.