Method for reducing warping stress of LED epitaxy

Abstract

The invention provides a method for reducing warping stress of LED epitaxy. The method comprises the steps of forming a GaN buffer layer on a sapphire substrate in an epitaxial mode, then growing a GaN layer on the GaN buffer layer in a three-dimensional mode, and forming a GaN epitaxial wafer which is provided with an island-shaped surface; after cooling is conducted, forming a double-layer thin film on the GaN epitaxial wafer provided with the island-shaped surface in an epitaxial mode, wherein the double-layer thin film comprises the GaN layer and an All-xGaxN layer, and forming double-layer thin films repeatedly in the epitaxial mode so as to form a superlattice on the GaN epitaxial wafer provided with the island-shaped surface; growing the GaN layer on the superlattice in a two-dimensional mode, and finishing preparation of a GaN base layer on the sapphire substrate. A superlattice inserting layer structure is adopted to adjust and release the warping stress between the GaN epitaxial layer growing in the two-dimensional mode and the sapphire substrate, accordingly, the warping degree when a light-emitting layer is grown on the epitaxial wafer is improved, wavelength difference between the central part and the edge part of the epitaxial wafer after the light-emitting layer is grown can be reduced, uniformity of the wavelength of the epitaxial wafer is improved, and accordingly the wave length yield of the epitaxial wafer is improved.

Description

Technical field [0001] The invention relates to the field of LED chip manufacturing, in particular to a method for reducing the epitaxial warping stress of the LED. Background technique [0002] MOCVD (Metal-Organic Chemical Vapor Deposition, metal organic chemical vapor deposition) is a new type of vapor phase epitaxy growth technology developed on the basis of vapor phase epitaxy (VPE) growth. MOCVD uses organic compounds of group III and group II elements and hydrides of group V and VI elements as crystal growth source materials, and conducts vapor phase epitaxy on the substrate by thermal decomposition reaction to grow various groups of III-V and II. -VI compound semiconductors and their multi-element solid solution thin layer single crystal materials. Generally, the crystal growth in MOCVD equipment is under normal pressure or low pressure (10-100 Torr). 2 In the cold wall quartz (stainless steel) reaction chamber, the substrate temperature is 500-1200℃, and the graphite pl...

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Problems solved by technology

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for reducing the warping stress of the LED epitaxy, which is used to solve the lattice mismatch and thermal deformation between the sapphire substrate and the GaN epitaxy in the prior art The stress generated by the difference causes the GaN epitaxial wafer to warp, which increases the degree of epitaxial warping when the epitaxial wafer grows the light-emitting layer, reduces the wavelength uniformity of the epitaxial wafer, and leads to a significant drop in the wavelength yield of the epitaxial wafer.

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