Processability of thin-film, fine-line pattern on aluminum nitride substrates [for hybrids]

The author investigated the processability of a thin-film line pattern, 76 μm, on AlN using sputter deposition and photolithography techniques. Results on the stability of AlN substrates in the processing environment, thin-film deposition, fine-line pattern generation, and laser scribability of AlN are reported. The surfaces of AlN substrates have been observed to decompose to an amorphous aluminum hydroxide phase when soaked in deionized water at 100°C for 30 min or longer. The surface of AlN was shown to oxidize rapidly to α-Al₂O ₃ when heated in air above 1000°C; this oxidized layer readily cracks during rapid cooling. AlN was found to be laser scribable. In this study, 53% of the circuits on AlN had opens as compared to none on Al₂O₃. This is attributed to the higher surface roughness of AlN, almost four times higher than that of Al₂O₃ substrates