Mechanical and structural characterization of in-situ phosphorus doped plasma enhanced alpha silicon films

Abstract

The mechanical and structural analysis of 350 degrees C deposited, plasma-enhanced and annealed alpha silicon films was performed. Very high, electrically active doping levels of phosphorus in silicon were achieved at even 750 degrees C anneal. The reason for such high activity is shown by TEM and electron diffraction analysis to be the formation of large polycrystallites when plasma-enhanced alpha silicon is annealed. This is in opposition to the small grain size with a large volume of grain boundaries when polysilicon is deposited at 650 degrees C and annealed further, later. Cantilever beams made out of alpha polysilicon were demonstrated, although it seems that the polysilicon is more suitable for micromechanical structures.<>