Aluminum nitride sintered body and method of producing the same

摘要

An aluminum nitride sintered body comprising aluminum nitride crystals belonging to a Wurtzite hexagonal crystal system wherein the 3 axes a, b and c of the unit lattice of the crystal are defined such that the ratio b/a of the lengths of the axes b and a is 1,000 near the center of the crystal grain and lies within the range 0.997-1.003 in the vicinity of the grain boundary phase. Aluminum nitride sintered body is produced by sintering a molded body of a raw material powder having aluminum and nitrogen as its principal components at a temperature of 1700 DEG -1900 DEG C. in a non-oxidizing atmosphere having a partial pressure of carbon monoxide or carbon of not more than 200 ppm and then cooling the sintered body to 1500 DEG C. or a lower temperature at a rate of 5 DEG C./min or less. The aluminum nitride sintered body has a greatly improved thermal conductivity and, therefore, is suitable for heat slingers, substrates or the like for semiconductor devices.