Micro-electromechanical system device including a precision proof mass element and methods for forming the same

A micro-electromechanical system (MEMS) device, comprising:

• a movable structure located in a lateral confinement that is surrounded by a semiconductor frame comprising a portion of a first semiconductor material, wherein the movable structure comprises a center mass portion and a first movable comb structure including a first inner comb shaft portion attached to a first sidewall of the center mass portion and first movable comb fingers laterally protruding from the first inner comb shaft portion, wherein:
• the center mass portion comprises another portion of the first semiconductor material;
• and
• the first movable comb structure comprises a dielectric liner that is physically exposed to a cavity within the matrix and a conductive fill material portion located within the first inner comb shaft portion and continuously extending into each of the first movable comb fingers and laterally enclosed by the dielectric liner.

A micro-electromechanical system (MEMS) device, comprising:

• a movable structure located in a lateral confinement, wherein the movable structure comprises a center mass portion and a first movable comb structure including a first inner comb shaft portion attached to a first sidewall of the center mass portion and first movable comb fingers laterally protruding from the inner comb shaft portion, wherein:
• the center mass portion comprises portion of a first semiconductor material;
• and
• a semiconductor oxide plate including an oxide of the first semiconductor material covers an entirety of a bottom surface of the center mass portion.