An aluminum nitride package for 600/spl deg/C and beyond

An aluminum nitride (AlN) based package was developed for use at temperatures up to 600/spl deg/C. AlN substrates were metallized with thick film refractory molybdenum (Mo) and with thin film refractory tungsten (W). The thick film Mo metallization was subsequently plated with nickel and gold, while thin film W was plated with gold. The sheet resistivities of the thick film Mo and thin film W metallizations were 0.025 ohms//spl square/ and 4.5 ohms//spl square/, respectively. The pull strengths of both metallizations were greater than 10 ksi. Four brazing alloys were investigated for attaching SiC die to metallized AlN substrate. The chemical compatibility of various bond pad materials with the metallizations were studied up to 900/spl deg/C.