Fabrication method of GaN-based composite substrate

Abstract

The invention relates to a fabrication method of a GaN-based composite substrate. The GaN-based composite substrate sequentially comprises a heat conduction and electric conduction transfer substrate, bonding dielectric layers and a GaN-based epitaxial thin film from bottom to top. The fabrication method comprises the following steps of firstly, epitaxially growing the GaN-based epitaxial thin film on a sapphire substrate to obtain a sapphire GaN-based composite substrate; secondly, respectively fabricating the bonding dielectric layers on a surface of the GaN-based epitaxial thin film and the heat conduction and electric conduction transfer substrate, and bonding the GaN-based epitaxial thin film with the heat conduction and electric conduction transfer substrate; and finally, removing the sapphire substrate to obtain the GaN-based composite substrate, and selectively performing surface treatment before transferring the GaN-based epitaxial thin film, during the transfer process and after transferring. The fabrication method is compatible with the advantages that the composite substrate achieved by transferring in the past possesses homoepitaxy and a vertical structural device can be directly fabricated, the composite substrate also has a low stress state and high-temperature stability, and subsequent GaN epitaxial growth and chip fabrication quality can be effectively improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductor optoelectronic devices, in particular to a preparation method of a GaN-based composite substrate. Background technique [0002] Wide bandgap GaN-based semiconductor materials have excellent optoelectronic properties and have been widely used in the production of light-emitting diodes, lasers, ultraviolet detectors and high-temperature, high-frequency, high-power electronic devices, and can be applied to the preparation of high-end microelectronics required by aerospace Devices, such as high-mobility transistors (HEMTs) and heterojunction transistors (HFETs), have become research hotspots in the international optoelectronics field. As for crystal epitaxy, no matter from the theory of epitaxial growth or the development history of semiconductor epitaxy technology, it has been proved that homoepitaxial is the best choice. Since the preparation of GaN bulk single crystal is very difficult, larg...

AI Technical Summary

Problems solved by technology

The composite substrate not only takes into account the homogeneous epitaxy required for GaN epitaxy, improves the crystal quality, but also can directly prepare vertical structure LEDs. At present, there are still some problems when using substrate transfer technology to prepare thermally and electrically conductive GaN composite substrates: 1) The strength of the bonding connection is not enough, and debonding and bubbling will occur in the subsequent homoepitaxial process; 2) During the bonding process, the preparation process introduces a very large stress, which will cause a large residual stress in the substrate, thereby Affect crystal quality and subsequent homoepitaxial effect; 3) In nitrogen polarity thermally conductive GaN composite substrate, laser lift-off surface burns seriously, which is not conducive to homoepitaxial, thus affecting device performance and stability

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