Mechanical and structural properties of in-situ doped PECVD Silicon Carbide layer for post-processing surface micromachining

In this paper, we report on mechanical and structural properties of in-situ n- and p-type PECVD Silicon Carbide (SiC) thin films for post-process surface micromachining. The effect of the doping on the film properties is investigated and compared to undoped layers. A clear increase in deposition rate is observed when adding the doping gas. The effect is more pronounced for p-type doping. The etch rate in a reactive ion etcher using fluorine-based chemistry is clearly affected by the doping gas level. For p-type films a slight decrease is observed, while for n-type films a sensible increase is measured. The stress is in the tensile region and somewhat larger than for undoped films. However, while for the phosphorous-doped films this increase is very small and almost insensitive to the doping gas level, for the boron-doped films the effect of doping level is much more pronounced. Structural and compositional analysis is preformed to understand the effect of the doping on the mechanical properties of these films.