Patent ID: 7754617

Claim:
A method of forming a thick polysilicon layer for a MEMS inertial sensor, the method comprising: forming a first mixed phase polysilicon film on a substrate in an elevated temperature environment for a period of time, the mixed phase polysilicon film having a crystalline film at least near the substrate and having an amorphous film at least near a surface of the mixed phase polysilicon film; forming an oxide layer on the first mixed phase polysilicon film; annealing the first mixed phase polysilicon film in an environment of about 1100° C. or greater to produce a crystalline polysilicon film throughout the first mixed phase polysilicon film; removing the oxide layer; and forming a second mixed phase polysilicon film on a surface of the crystalline polysilicon film in an elevated temperature environment for a period of time, the second mixed phase polysilicon film having a second crystalline film at least near the surface of the crystalline polysilicon film and having a second amorphous film at least near a surface of the second mixed phase polysilicon film.