INSIDE REFORMING SUBSTRATE FOR EPITAXIAL GROWTH; CRYSTAL FILM FORMING ELEMENT, DEVICE, AND BULK SUBSTRATE PRODUCED USING THE SAME; AND METHOD FOR PRODUCING THE SAME

摘要

Provided is a sapphire substrate mainly for epitaxial growth of a nitride semiconductor layer, wherein the shape and/or the amount of deflection of the substrate can be efficiently and accurately controlled; and the deflection of the substrate occurring when a film is formed is suppressed so that the deflection behavior of the substrate can be reduced.  Further, a film forming element for a nitride semiconductor layer, a nitride semiconductor device, and a nitride semiconductor bulk substrate, which are produced using the sapphire substrate, and a method for producing the same are provided. Pulse lasers are concentrated in the inside of the sapphire substrate through the polished surface of the sapphire substrate, to scan the inside of the sapphire substrate, and reforming region patterns are formed using multiphoton absorption performed by the pulse lasers, so that the shape and/or the amount of deflection of the substrate can be controlled.  When a nitride semiconductor layer is formed using the sapphire substrate, the deflection of the substrate occurring when a film is formed can be suppressed, and the deflection behavior of the substrate can be reduced.  Thus, the quality and the uniformity of the film can be improved, and the quality and the yield ratio of the nitride semiconductor device can be improved.