KR100949212B1 - Method for manufacturing substrate of Nitride chemical substrate - Google Patents

Abstract

The present invention relates to a method for manufacturing a nitride substrate, and to improve the size of the nitride substrate using a silicon substrate as a substrate on which the nitride layer is grown, and to form a polycrystalline buffer layer on the silicon substrate by using sapphire or the like on the order of hundreds of microns. This allows separation using simple chemical etching or mechanical polishing methods without the use of complicated laser lift off methods.

Silicon, Substrate, Separation, Polycrystalline, Buffer Layer, Sapphire

Description

Method for manufacturing substrate of Nitride chemical substrate

1A to 1B are process flowcharts showing a general method of manufacturing a nitride substrate,

2a to 2c is a process flow chart showing a nitride substrate manufacturing method according to the invention,

3 is a diagram illustrating an apparatus in which the nitride substrate manufacturing method of the present invention is used.

Explanation of symbols on the main parts of the drawings

20 silicon substrate 21 polycrystalline sapphire layer

22 gallium nitride layer 30 electric furnace

31 chamber 32 injection tube

33: boat 34: reaction tube

35: susceptor

The present invention enables the nitride substrate to be grown using a silicon substrate to improve the size of the nitride substrate, and by using a sapphire or the like on the silicon substrate to form a polycrystalline buffer layer in the order of hundreds of microns, laser lift-off of complex process The present invention relates to a method for manufacturing a nitride substrate that can be separated by a simple chemical etching or mechanical polishing method without using the method.

Recently, as the demand for high-efficiency short-wavelength optical devices increases, many studies on compound semiconductors of nitride-based materials known to be suitable for such applications have been conducted.

      In particular, gallium nitride (GaN), a nitride-based material, is a wide bandgap semiconductor having a band gap energy of 3.39 eV, a direct transition type, and is a useful material for manufacturing a light emitting device having a short wavelength region.

      These gallium nitrides require high temperatures of 1500 ° C or higher and nitrogen pressures of about 1500 atm or higher for normal liquid crystal growth due to the high nitrogen vapor pressure at the melting point, which is difficult to mass produce, and the size of crystals currently available is 80 mm2. Because of its thin plate shape, it is difficult to use this for device fabrication.

    Therefore, gallium nitride is grown on sapphire substrates by vapor phase growth methods such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride or halide vapor phase epitaxy (HVPE), and sublimition vapor phase epitaxy (SVPE). 1A and 1B illustrate a manufacturing process of such a gallium nitride substrate.                         

As shown in FIG. 1, in the manufacturing process of the gallium nitride substrate, first, as shown in FIG. 1A, the gallium nitride layer 11 is grown on the sapphire substrate 10 by using the above-described vapor phase growth method.

When the growth is complete, a square or circular spot laser, such as a Q-switched Nd: YAG with a wavelength of 355 nm or an excimer laser with a wavelength of 248 nm, is applied to the sapphire substrate and the gallium nitride layer interface. Focus and investigate.

Then, the thermal energy of the laser light is concentrated on the interface between the gallium nitride layer and the sapphire substrate, and the temperature is about 800 ° C., which is high enough to separate the gallium metal and the nitrogen molecules, thereby providing gallium nitride momentarily at the portion where the laser light passes. And separation of the sapphire substrate occurs, and the manufacture of the free standing gallium nitride substrate is completed (FIG. 1B).

However, this manufacturing process uses a sapphire substrate as a base material, which causes a large number of defects and warpage at the interface due to the difference in the coefficient of thermal expansion or lattice constant with the gallium nitride layer, and the gallium nitride on the sapphire substrate The growth of the layer has a problem that the size of the gallium nitride substrate is limited.

In addition, since the sapphire substrate does not have an appropriate etching solution, the sapphire substrate and the gallium nitride layer must be separated using a laser lift-off method even after the growth of the gallium nitride layer. There is a problem that requires a lot of time.

 Accordingly, the present invention was developed to solve the above problems, and when the nitride layer is grown and the grown nitride layer is separated from the substrate used as the base material, a simple chemical etching or mechanical process is not necessary without using a laser lift-off method of a complicated process. It is an object of the present invention to provide a method of manufacturing a nitride substrate that can be separated by a polishing method and can also improve the size of the nitride substrate by using a substrate that can be used as a base material to have a size of several inches or more. .

To this end, the present invention is to improve the size of the nitride substrate by using a silicon substrate as a base material on which the nitride layer is grown, and to form a polycrystalline buffer layer on the silicon substrate by using a sapphire or the like on the order of hundreds of microns, a complex process of They can be separated using simple chemical etching or mechanical polishing without the use of a laser lift-off method.

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

First, the method of manufacturing a nitride substrate of the present invention may include a metal organic chemical vapor deposition (MOCVD), a molecular beam epitaxy (MBE), a hydride or halide vapor phase epitaxy (HVPE), and a vapor growth method such as a sublimition vapor phase epitaxy (SVPE). A poly-crystal buffer layer is formed on the substrate, the substrate on which the nitride layer is grown.

At this time, the substrate is preferably any one selected from a silicon (Si) substrate or a silicon carbide (SiC) substrate, in particular, a silicon (Si) substrate that can be a substrate of several inches or more in size Most preferably.

In addition, sapphire (Al ₂ O ₃ ) is used as the buffer layer of the polycrystal, and the thin film is deposited to a few tens of micrometers so as to be used as a layer for absorbing stress of a substrate such as a silicon substrate and a nitride layer to be grown thereon. desirable.

Next, when the polycrystalline buffer layer is deposited on the substrate of the base material, the nitride layer is grown by using a hydride or halide vapor phase epitaxy (HVPE) on the deposited buffer layer.

Then, finally, the nitride layer is separated from the substrate using any one selected from an etching solution or mechanical lapping, and the polycrystalline buffer layer under the nitride layer is removed by etching to form a free standing nitride substrate. The manufacturing process is complete.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 2A to 2C.

In the embodiment to be described, nitride is made of gallium nitride (GaN), and the substrate and the polycrystalline buffer layer are each made of a silicon (Si) substrate and a sapphire layer, and a halide vapor deposition method (HVPE) is used as the nitride growth method.

First, an embodiment of the present invention, as shown in Figure 2a, a polycrystalline sapphire layer of a buffer layer on top of the silicon substrate 20, the base material on which the gallium nitride layer is grown using a halide vapor phase growth method (buffer layer) 21 is formed.

At this time, the polycrystalline sapphire layer (Al ₂ O ₃ ) 21, which is the buffer layer, is deposited to a thickness of about several tens of microseconds so as to stress the silicon substrate 20 and the gallium nitride layer to be grown on the polycrystalline sapphire layer 21. It is desirable to be able to use it as a layer for absorbing.

When the polycrystalline sapphire layer 21 is deposited on the base silicon substrate 20, the gallium nitride layer 22 may be formed on the deposited polycrystalline sapphire layer 21 by using a hydride or halide vapor phase epitaxy (HVPE). 3 shows a device used in the growth of the gallium nitride layer, and a process of growing the gallium nitride layer using the device will be described below.

First, the substrate manufacturing apparatus illustrated in FIG. 3 includes an electric furnace 30 mounted on an outer circumferential surface thereof and a chamber 31 heated to a high temperature, and mounted on one side of the chamber 31 to inject N ₂ generated gas. An injection tube 32 and one side of the chamber 31 are mounted to be spaced apart from the injection tube 32 by a predetermined distance, and the gallium boat 33 is accommodated therein so that the reaction gas and the gallium boat injected from the outside ( A reaction tube 34 for discharging the generated reactant combined with the gallium molecules contained in 33), and an N ₂ product gas injected through the injection tube 32 and seated on an inner surface of the chamber 31; It consists of a susceptor 35 supporting the silicon substrate so that the nitride formed by combining the reactants discharged from the reaction tube 34 is deposited and grown.

In the method of manufacturing a gallium nitride substrate using the device thus formed, first, the temperature of the chamber 31 is adjusted and maintained at about 800 ° C. to 1000 ° C., which is a nitride layer growth temperature, using heat heated in the electric furnace 30.

In this state, a reaction gas is injected into the reaction tube 34 to chemically react with the group III member powder contained in the boat 33.

At this time, the reaction gas is hydrogen chloride (HCL), the Group III member powder is preferably used any one selected from gallium nitride powder, metal gallium or a mixture thereof.

Meanwhile, a specific reactant gallium chloride (GaCl) is formed according to a chemical reaction between hydrogen chloride (HCL) injected through the reaction tube 34 and gallium powder contained in the boat 33. The chemical reaction formula is as follows. Is the same as

2Ga + 2HCL -> 2GaCl + H _{2 ↑}

Next, when the gallium chloride (GaCl) gas formed in the boat 33 is discharged into the chamber 31, the N ₂ generation gas is injected through the injection pipe 32 connected to one side of the chamber 31. .

Then, in the chamber 31, gallium nitride is formed by combining N ₂ generated gas and gallium chloride (GaCl) gas discharged from the reaction tube 34, and the gallium nitride is formed by the susceptor 35. It is deposited and grown on the upper front surface of the supported silicon substrate.

At this time, the N ₂ product gas is preferably used ammonia (NH ₃ ) gas, the chemical reaction equation for the formation of gallium nitride is as follows.

GaCl + NH _3- > GaN + HCL + H _{2 ↑}

Meanwhile, when the gallium nitride layer 22 is deposited and grown using HVPE (hydride or halide vapor phase epitaxy) on the deposited polycrystalline sapphire layer 21, the silicon substrate 20 is finally NH ₃ OH. Etching solution such as, or any one selected from mechanical lapping is separated (Fig. 2c).

Then, finally, the polycrystalline sapphire layer 21 under the gallium nitride layer 22 is removed to obtain a free standing gallium nitride substrate.

As described above, by using a silicon substrate as a base material on which the nitride layer is grown, and forming a polycrystalline buffer layer on the silicon substrate by using sapphire or the like on the order of several hundred micrometers, the laser lift-off method of a complicated process as in the conventional art It can be separated by a simple chemical etching or mechanical polishing method without using.

As described in detail above, the nitride substrate manufacturing method of the present invention, by using a silicon substrate as a base material on which the nitride layer is grown to improve the size of the nitride substrate, by using a sapphire or the like on the silicon substrate to a few hundred kPa By forming the polycrystalline buffer layer, there is an effect that can be separated by a simple chemical etching or mechanical polishing method without using a laser lift-off method of a complicated process.                     

Although the invention has been described in detail only with respect to the specific examples described, 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.

Claims (4)

Forming a sapphire layer on the substrate by vapor phase growth; Forming a nitride layer on the sapphire layer; A third step of mechanically wrapping the substrate to separate the sapphire layer and the nitride layer; And a fourth step of forming the nitride substrate by removing the sapphire layer from the sapphire layer and the nitride layer from which the substrate is separated. The method of claim 1, wherein the substrate; A method for producing a nitride substrate, characterized in that any one of a silicon (Si) substrate or a silicon carbide (SiC) substrate. delete delete

Images