Method for efficiently grinding and polishing GaN chips

Abstract

The invention provides a method for efficiently grinding and polishing GaN chips, namely the photoelectrochemistry mechanical polishing method for efficiently grinding the GaN chips. The method includes the steps that under the effects of illumination and an external electric field, the to-be-polished surfaces of the GaN chips are oxidized to form gallium oxide, the gallium oxide and hydroxyl ions in a polishing solution are combined to form gallium hydroxide passivation layers, and the gallium oxide and hydrogen ions in the polishing solution are combined to form gallium ions; and under the protection of the gallium hydroxide passivation layers and the polishing solution rich in gallium ion, illumination and oxidation on concave parts of the to-be-polished surfaces are effectively restrained, high convex parts of the to-be-polished surfaces are mechanically removed, and new GaN surfaces are exposed and continue to be selectively removed through illumination and oxidation. The illumination intensity, voltage values and pressure applied to an upper tray are regulated and controlled, the oxidation speed of the to-be-polished surfaces of the chips is matched with the mechanical removing speed, and therefore the surface flatness and polishing efficiency of the GaN chips are improved, and high-quality polished GaN chips are obtained.

Description

technical field [0001] The invention relates to the technical field of semiconductor optoelectronic materials, in particular to a photoelectrochemical mechanical method for grinding and polishing GaN wafers with high efficiency. Background technique [0002] Gallium Nitride (GaN) has been extensively researched and applied due to its excellent performance, which can be applied to the preparation of high-power high-frequency devices and other semiconductor devices that work under special conditions. The crystal quality of the GaN epitaxial layer is the fundamental guarantee for the realization of high-performance GaN-based devices. The use of GaN single crystal substrates to realize homoepitaxy is the main way to improve the crystal quality of GaN epitaxial layers and GaN-based devices. [0003] GaN single crystal substrates generally undergo surface treatment such as grinding and polishing before epitaxy, so as to obtain crystal planes that are conducive to crystal epitaxia...

AI Technical Summary

Problems solved by technology

The polishing method of GaN wafers mainly adopts chemical mechanical polishing (CMP), which mainly uses chemical raw materials (polishing liquid) to chemically modify the surface to be polished, and then uses mechanical methods to remove the modified layer. This mechanically assisted polishing method is easy to cause surface damage. Mechanical damage, especially for GaN, a material with high hardness and high brittleness, often leaves surface scratches, making it difficult to obtain a high-quality polished surface

Chinese patents CN101220244A and CN 104364331 A improve the surface quality of polished GaN wafers by improving the composition and proportion of the polishing liquid. However, due to the stable physical and chemical properties of GaN, the polishing cycle is long and the efficiency is low.

The electrochemical mechanical polishing method (Chinese patent CN103114323 A) accelerates the oxidation and corrosion of the GaN surface under the assisted action of the electric field, which can effectively improve the mechanical scratches of CMP and improve the polishing effect. However, due to the oxidation and corrosion of the electric field everywhere on the surface to be polished The effect is basically the same, hindering the improvement of polishing efficiency

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