Annealing method of sapphire wafer

Abstract

The invention relates to an annealing method of a sapphire wafer, belonging to the technical field of the machining of a crystalline material. The invention provides the annealing method of the high-quality sapphire wafer, comprising the following steps of: raising the temperature on the sapphire wafer which is cut, milled or polished by sections and keeping the heat for a period of time at 900-1600 DEG C; carrying out annealing treatment on the sapphire wafer so as to eliminate machining stress for cutting, milling or polishing; and rotating the wafer at a heat-preservation phase to uniformly anneal the whole wafer, so as to eliminate the influence that a temperature field of an annealing furnace is not uniform. The machining stress of the wafer annealed by the method is basically eliminated and the whole wafer is uniformly annealed; and the warping degree of the annealed wafer is small.

Description

Technical field [0001] The invention relates to the technical field of processing crystal materials, in particular to a method for annealing a sapphire wafer. Background technique [0002] Sapphire crystal (Al 2 O 3 ) Is the most commonly used substrate material for the ultra-high brightness blue and white LED luminescent material GaN, and the crystal quality of GaN epitaxy is closely related to the surface processing quality of the sapphire substrate (substrate) used, especially the patterned substrate ( PSS is closely related to the surface morphology and the degree of warpage of the wafer. At the same time, if the degree of warpage of the wafer is too large, the flat wafer and the epitaxial film will fall off when the flat wafer is used for GaN epitaxy, and the PSS will be difficult to focus, which affects the quality of the epitaxy. During the cutting, double-sided grinding, single-sided grinding and polishing of the sapphire substrate, although part of the processing stress ...

AI Technical Summary

Problems solved by technology

[0002] Sapphire crystal (Al 2 o 3 ) is the most commonly used substrate material for ultra-high brightness blue and white LED luminescent materials GaN, and the crystal quality of GaN epitaxy is closely related to the surface processing quality of the sapphire substrate (substrate) used, especially the patterned substrate ( PSS) is closely related to the surface morphology and warpage of the wafer. At the same time, if the warpage of the wafer is too large, when the flat wafer is used for GaN epitaxy, the flat wafer and the epitaxial film will fall off, and the PSS will be difficult to focus, which will affect the epitaxial quality.

During the cutting, double-side grinding, single-side grinding, and polishing of sapphire substrates, although part of the processing stress will be released in the next processing step, this stress release is disorderly release, and the unreleased processing stress will be released on the wafer. Agglomeration on the surface affects the degree of warpage of the sapphire wafer. Severe warpage will produce fragments in the subsequent processing process, which will affect the quality of the wafer in the entire processing cycle.

[0003] During the processing of the sapphire substrate, it must be annealed to reduce the processing stress. The current annealing process uses a one-step temperature rise to the annealing temperature, without a process of heat preservation, and the processing stress is not released uniformly, and the sapphire wafer does not move in the annealing furnace. The temperature field of the furnace has a great influence on the uniformity of processing release, especially for large-sized sapphire wafers