METHOD FOR SEPARATING GROUP 13 ELEMENT NITRIDE LAYER, AND COMPOSITE SUBSTRATE

摘要

A composite substrate which is provided with a sapphire substrate and a group 13 element nitride layer provided on the sapphire substrate is prepared. The group 13 element nitride layer is formed of gallium nitride, aluminum nitride or gallium aluminum nitride. The composite substrate satisfies relational expressions (1), (2) and (3). By irradiating the composite substrate with laser light from the sapphire substrate side, crystal lattice bonds at the interface between the sapphire substrate and the group 13 element nitride layer are broken. 5.0 ≤ ((Average thickness (μm) of group 13 element nitride layer)/(Diameter (mm) of sapphire substrate)) ≤ 10.0 (1) 0.1 ≤ (Warp (mm) of composite substrate) × (50/(Diameter (mm) of composite substrate))2 ≤ 0.6 (2) 1.10 ≤ (Maximum value of thickness (μm) of group 13 element nitride layer)/(Minimum value of thickness (μm) of group 13 element nitride layer) (3)