Patent ID: 7943525

Claim:
A method for producing a micromechanical systems (MEMS) device with isolated microstructures comprising: providing a substrate; forming a sacrificial layer overlying said substrate; forming a polysilicon structural layer overlying said sacrificial layer; forming an isolation trench in said polysilicon structural layer by etching said isolation trench through said polysilicon structural layer and depositing an insulating material in said isolation trench to form isolated microstructures in said polysilicon structural layer that are laterally anchored to said isolation trench, said etching said isolation trench exposing an underlying portion of said sacrificial layer, and said depositing said insulating material comprising: applying a mask to a top surface of said polysilicon structural layer; depositing an insulating film in said isolation trench and overlying said mask, said insulating film lining sidewalls of said polysilicon structural layer and said exposed underlying portion of said sacrificial layer to form a sub-trench; depositing a sacrificial material over said insulating film in said isolation trench and on said insulating film overlying said mask, said sacrificial material filling said isolation trench; removing said insulating film and said sacrificial material from said top surface using a first etching process; removing said sacrificial material from said isolation trench and said mask using a second etching process; and depositing said insulating material in said sub-trench to fill said sub-trench following removal of said sacrificial material; forming electrical connections over said isolation trench; and selectively removing said sacrificial layer such that said isolated microstructures of said MEMS device are spaced apart from said substrate.