Method for manufacturing nitride semiconductor substrate, nitride semiconductor substrate, and laminate structure

A nitride semiconductor substrate, having a diameter of 2 inches or more and having a main surface whose closest low index crystal plane is a (0001) plane,

• wherein X-ray rocking curve measurement for (0002) plane diffraction, which is performed to the main surface by irradiating with (Cu) Kα1 X-rays through a two-crystal monochromator of Ge (220) plane and a slit, reveals that:
• a variation obtained by a difference between maximum and minimum in a size of an off-angle within a diameter of 29.6 mm from a center of the main surface is 0.075° or less,
• wherein the off-angle is an angle of <0001> axis with respect to a normal of the main surface measured based on a diffraction peak angle of the (0002) plane, and
• difference FWHMa-FWHMb obtained by subtracting FWHMb from FWHMa is 30% or less of FWHMa,
• wherein FWHMa is full width at half maximum of the (0002) plane diffraction when a slit width in ω direction is 1 mm, and
• FWHMb is full width at half maximum of the (0002) plane diffraction when a slit width in ω direction is 0.1 mm.

A nitride semiconductor substrate, having a diameter of 2 inches or more and having a main surface whose closest low index crystal plane is a (0001) plane,

• wherein X-ray rocking curve measurement for (0002) plane diffraction, which is performed to the main surface by irradiating with (Cu) Kα1 X-rays through a two-crystal monochromator of Ge (220) plane and a slit, reveals that:
• difference FWHMa-FWHMb obtained by subtracting FWHMb from FWHMa is 30% or less of FWHMa,
• wherein FWHMa is full width at half maximum of the (0002) plane diffraction when a slit width in ω direction is 1 mm,
• FWHMb is full width at half maximum of the (0002) plane diffraction when a slit width in ω direction is 0.1 mm, and
• a difference between a first radius of curvature of the (0001) plane in a direction along <11-20> axis and a second radius of curvature of the (0001) plane in a direction along the <1-100> axis obtained based on a diffraction peak angle of the (0002) plane, is 50% or less of the larger radius of curvature among the first radius of curvature and the second radius of curvature.