Substrate and epitaxial wafer for flip LED chips and making methods thereof

Abstract

The invention provides a substrate and an epitaxial wafer for flip LED chips and making methods thereof. The substrate comprises a gallium nitride substrate material and a dielectric layer with a graphical structure, and the dielectric layer is embedded into the gallium nitride substrate material. The substrate making method comprises the following steps: forming a lattice matching layer on a sapphire substrate; forming a dielectric layer with a graphical structure on the lattice matching layer, wherein the dielectric layer exposes part of the lattice matching layer; growing a gallium nitride substrate material on the lattice matching layer and the dielectric layer until the lattice matching layer and the dielectric layer are completely separated due to the stress of the gallium nitride substrate material; and removing at least part of the lattice matching layer. Both the gallium nitride substrate material and the dielectric layer embedded in the gallium nitride substrate material adopted by the substrate for flip LED chips provided by the invention have double functions of internal quantum efficiency increasing and external quantum efficiency increasing.

Description

technical field [0001] The invention belongs to the field of semiconductor optoelectronic chip manufacturing, in particular to a substrate for flip-chip LED chips, an epitaxial wafer and a manufacturing method thereof. Background technique [0002] Since gallium nitride (GaN)-based LEDs were commercialized in the early 1990s, after more than 20 years of development, their structures have become mature and perfect, and they have been able to meet people's current needs for lamp decoration; To replace traditional light sources and enter the lighting field, especially the high-end lighting field, the improvement of luminous brightness is the never-ending pursuit of scientific researchers in the LED industry. [0003] The root cause of the limited improvement of LED luminous brightness is the lack of natural gallium nitride substrate materials in nature. There are very few heterogeneous substrate materials that can be used for gallium nitride-based LEDs, and even fewer substrate...

AI Technical Summary

Problems solved by technology

However, the inventors found that the flip-chip LED chip structure emits light on the N surface. Since the refractive index of sapphire is lower than that of gallium nitride, the light emitted from the epitaxial layer will be reflected on the interface between the sapphire and the substrate. As a result, more light cannot be emitted, especially the patterned substrate currently used in the mainstream LED chip structure has scattering and diffuse reflection effects, which is more likely to cause more light not to be emitted, reducing the light extraction efficiency; but if Without the use of patterned substrate technology, the internal quantum efficiency of LED chips cannot be fully utilized

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