| abstract |
Disclosed are a silicon nitride board formed of a silicon nitride sintered compact having a high strength and a high coefficient of thermal conductivity, and a method for manufacturing the silicon nitride board. Also disclosed are a silicon nitride circuit board and a semiconductor module using the silicon nitride board. The silicon nitride board including crystal grains (11) of β-type silicon nitride and a grain boundary phase containing at least one rare earth element (RE), magnesium (Mg), and silicon (Si) is comprised of a silicon nitride sintered compact, wherein the grain boundary phase comprises an amorphous phase (12) and an MgSiN 2 crystal phase (13), the X-ray diffraction line peak intensity of a crystal plane of all of crystal phases containing the rare earth element (RE) is less than 0.0005 times the sum of the diffraction line peak intensities of (110), (200), (101), (210), (201), (310), (320), and (002) of the β-type silicon nitride crystal grains, and the X-ray diffraction line peak intensity of (121) of the MgSiN 2 crystal phase (13) is 0.0005 to 0.003 times the sum of the X-ray diffraction line peak intensities of (110), (200), (101), (210), (201), (310), (320), and (002) of the β-type silicon nitride crystal grains. |