| abstract |
The invention provides a large silicon nitride sintered substrate and a manufacturing method thereof. The silicon nitride sintered substrate has a main surface (101a) larger than a square with a side of 120 mm, and the ratio dc/de of the density dc at the center of the main surface (101a) to the density de at the ends is 0.98 or more The central portion of the main surface (101a) has a void ratio vc of 1.80% or less, and an end portion of the void ratio ve of 1.00% or less. Preferably, the density dc of the central portion is 3.120 g/cm 3 or more, the density de of the end portions is 3.160 g/cm 3 or greater, and the ratio ve/vc of the porosity vc of the central portion to the porosity ve of the end portions is: 0.50 or more. |