Highly thermally conductive silicon nitride sintered body, silicon nitride substrate, silicon nitride circuit board, and semiconductor device

Abstract

According to an embodiment, a highly thermally conductive silicon nitride sintered body includes silicon nitride crystal grains and a grain boundary phase. A thermal conductivity of the silicon nitride sintered body is not less than 80 W/(m·K). An average value of solid solution oxygen amounts of the silicon nitride crystal grains existing in a 20 μm×20 μm unit area in any cross section is not more than 0.2 wt %. An average value of major diameters of the silicon nitride crystal grains existing in a 50 μm×50 μm unit area in any cross section is not less than 1 μm and not more than 10 μm. An average of aspect ratios of the silicon nitride crystal grains existing in the 50 μm×50 μm unit area is not less than 2 and not more than 10.

Dependencies are inferred from the claim text.