Properties comparison of plasma-deposited SiOx and SiNx films applied to supporting films in an infrared scene projector device

Abstract

Microemitter resistor arrays are one popular approach to obtaining an infrared scene projector capable of wide dynamic range. Typically, the array operates in a two-level architecture wherein the array resides suspended on support legs. In the microbridge pixel structure, the support legs films must have low thermal conductivity, high mechanical strength, minimal stress and good thermal stability. Usually, silicon nitride (SiNx) films can meet the requirement and have been used as support films in dynamic infrared scene generation. While compared with the silicon nitride films, the silicon oxide (SiOx) films have a lower thermal conductivity. If the SiOx films can also be used as support films in the device instead of SiNx films, it can reduce the thermal loss further. Namely, the SiOx films can make the pixel to achieve higher temperature and higher radiance with lower power than silicon nitride films do. In this work, SiOx and SiNx films were deposited in a PECVD reactor .The stress, Young modulus, Hardness, thermal stability, and infrared optical absorption properties of the two types of films were investigated and compared.