LED epitaxial wafer growth method

Abstract

The present invention discloses an LED epitaxial wafer growth method. The method comprises the steps of: arranging a sapphire substrate of an AlN film at a processing surface, growing a first gradualchange AlGaN layer, a second gradual change AlGaN layer and a third gradual change AlGaN layer in order on the sapphire substrate, growing a low-temperature buffer layer, an un-doped GaN layer and a Si-doped N-type GaN layer, periodically growing an active layer MQW, growing a P-type AlGaN layer, growing a Mg-doped P-type GaN layer, and performing cooling. The first gradual change AlGaN layer, thesecond gradual change AlGaN layer and the third gradual change AlGaN layer are grown to reduce the dislocation density, improve the crystalline quality, reduce the warping of an epitaxial wafer, improve the percent of pass of the GaN epitaxial wafer and improve the LED luminous efficiency. The gradual change AlGaN layers are subjected to annealing processing to allow the whole surface of the epitaxial wafer to be smoother, allow the surface hexagonal defects and the hollow pits to be fewer and allow the whole appearance to be better.

Description

technical field [0001] The invention relates to the technical field of growing LED epitaxial wafers, in particular to a method for growing LED epitaxial wafers. Background technique [0002] The commonly used GaN growth method is patterning on a sapphire substrate. Sapphire crystal is one of the best substrate materials for the growth of GaN epitaxial layer, the third-generation semiconductor material, and its single crystal preparation process is mature. GaN is used as a base material for blue LEDs. Among them, SiC, the substrate material of the GaN epitaxial layer, has a small lattice mismatch with GaN, only 3.4%, but its thermal expansion coefficient is quite different from that of GaN, which is easy to cause GaN epitaxial layer fracture, and the manufacturing cost is high, which is 10% of that of sapphire. times; the cost of the substrate material Si is low, and the lattice mismatch degree with GaN is large, reaching 17%. It is difficult to grow GaN, and the luminous e...

AI Technical Summary

Problems solved by technology

However, since the low-temperature buffer layer is still hetero-epitaxy, its improved crystal quality is limited.

In addition, due to the large lattice mismatch between the epitaxial film layers, the epitaxial crystal film has been subjected to stress during the growth process, resulting in bending and warping of the epitaxial film.

When the traditional low-temperature buffer layer method is used to grow epitaxial crystals on large-size sapphire substrates, the warpage of the epitaxial wafers is large, resulting in a high rate of grinding fragments and low product yields in the subsequent chip manufacturing process

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