Hard AlN films prepared by low duty cycle magnetron sputtering and by other deposition techniques

Abstract

Crystalline AlN films are very attractive due to their properties such as high thermal stability and relatively high hardness and piezoelectric response. However, the deposition of dense textured AlN films with superior quality at a high deposition rate remains a challenge. In the present work, a reactive low duty cycle pulsed direct current magnetron sputtering (LDMS) process was employed to deposit AlN films on glass and silicon substrates. An arc-free discharge on the Al target was achieved by using short voltage pulses of 10 μs at a low duty cycle of 10%. The authors optimized the deposition conditions in terms of reactive gas flow, working pressure, average target power, substrate temperature, substrate bias, and the level of target erosion. With the optimized deposition conditions, the authors were able to obtain transparent crystalline AlN films with strong (002) preferential orientation and very good optical and mechanical properties: The AlN films with the highest refractive index of 2.1 present ...