Patent ID: 9321647
Filing Date: 2016-04-26
CPC Classification: C01B,C04B,Y10T

Claim Text:
1. A polycrystalline aluminum nitride substrate, said substrate being prepared according to a method comprising: pressing aluminum nitride powder to form a pressed aluminum nitride slug; sintering the pressed aluminum nitride slug material by heating to a maximum temperature of at least about 1,500° C. at a heating rate that does not exceed 0.1° C./minute to 10° C./minute in a non-oxidizing atmosphere to form a sintered aluminum nitride boule with a thickness of at least 5 cm and with a diameter or length or width of at least 5 cm; and mechanically polishing at least a portion of the sintered aluminum nitride boule to form a polycrystalline aluminum nitride substrate, such that the so-formed substrate has a relative density of at least about 98%, an aluminum nitride purity of at least about 98% by weight, an rms surface roughness of less than about 80 nm, and a defect density of less than about 1,000 cm −2 .