Silicon nitride substrate, silicon nitride circuit substrate, and evaluation method, evaluation device, and evaluation system for silicon nitride substrate and silicon nitride circuit substrate

Abstract

A silicon nitride substrate including a first surface, and a second surface disposed opposite the first surface. One of the first surface or the second surface is a measurement surface. On the measurement surface, a value of an average full-width-at-half-maximum (FWHM) Cis broader than 0 cmand narrower than 5.32 cmas measured by using a following measurement method. The measurement method of the average full-width-at-half-maximum (FWHM) C: one central point and four edge portions on the measurement surface are determined as measurement points; a Raman spectrum is measured at each of the measurement points; a full-width-at-half-maximum (FWHM) C of a spectral peak having the maximum strength within a range from 850 cmor greater to 875 cmor less is calculated in each Raman spectrum; and an average value of thus calculated full-width-at-half-maximum (FWHM)s C is the average full-width-at-half-maximum (FWHM) C.