Composite substrate, preparation method of composite substrate and method for preparing single crystal thick film through hetero-epitaxy

Abstract

The embodiment of the invention discloses a composite substrate which is used to prepare a nitride (III) semiconductor single crystal thick film through epitaxial growth. The composite substrate is characterized by comprising a heterogeneous substrate and a buffer layer on the heterogeneous substrate, wherein the thickness of the heterogeneous substrate is 0.5-13mm. As the composite substrate has high thickness, after the single crystal thick film is grown on the composite substrate and the growing temperature is reduced to the room temperature, the stress on the composite substrate is less than the fracture stress; and when the single crystal thick film has proper or even higher thickness, the composite substrate can not be broken and then the single crystal thick film can not be broken. Therefore, the size of the formed single crystal thick film can be ensured and the large crystal thick film can be obtained.

Description

technical field [0001] The invention relates to semiconductor manufacturing technology, more specifically, to a composite substrate and a manufacturing method thereof, and a method for preparing a single crystal thick film by heteroepitaxial growth. Background technique [0002] The third-generation semiconductor materials are also called wide-bandgap semiconductors because their energy bandgap is generally greater than 3.0 electron volts. Compared with traditional silicon-based and gallium arsenide-based semiconductor materials, wide bandgap semiconductors, such as silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN) and indium nitride (InN), etc., due to Its unique band gap range, excellent optical and electrical properties and excellent material properties can meet the working requirements of high-power, high-temperature, high-frequency and high-speed semiconductor devices. Wide application prospects. Among them, gallium nitride, aluminum nitride and ind...

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Problems solved by technology

[0005] However, since the thermal expansion coefficient of sapphire is greater than that of gallium nitride, when cooling from the growth temperature to room temperature, the lattice change of sapphire is greater than that of gallium nitride, so that tensile stress will be generated on the sapphire substrate , compressive stress is generated on the GaN single crystal thick film, and the overall structure of the GaN single crystal thick film and the sapphire substrate will warp after cooling down to room temperature

At present, the thickness of the sapphire substrate of the general industrial specification is 430 microns. If the thickness of the grown gallium nitride single crystal thick film reaches a certain value (such as exceeding 200 microns), the tensile stress on the sapphire substrate will reach more than 200 MPa. , and the thickness of the grown gallium nitride single crystal usually reaches more than 400 microns, when the tensile stress generated on the sapphire exceeds its fracture stress, it will cause the sapphire substrate to crack

[0006] When the sapphire substrate is broken, the following two factors will also lead to cracking of the gallium nitride single crystal: first, the interface between sapphire and gallium nitride is continuous, and the gallium nitride on the sapphire is broken at the moment of cracking. Cracking of single crystal thick film; Second, cracking of gallium nitride single crystal thick film due to warping deformation

Based on this, the size of the GaN single crystal thick film obtained is often smaller than the size of the original sapphire substrate, which limits the size of the GaN single crystal thick film grown by the HVPE method, which is not conducive to the industrialization of this method.

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