MEMS integrated pressure sensor devices and methods of forming same

A method for forming a micro-electromechanical (MEMS) device comprising:

• providing a MEMS wafer comprising:
• a MEMS substrate;
• a first oxide release layer over the MEMS substrate;
• and
• a polysilicon layer over the first oxide release layer, wherein the polysilicon layer comprises first and second portions;
• bonding a carrier wafer to a first surface of the MEMS wafer, wherein bonding the carrier wafer creates a first cavity, and wherein a first surface of the first portion of the polysilicon layer is exposed to a pressure level of the first cavity;
• providing a MEMS structure aligned with the second portion of the polysilicon layer, wherein providing the MEMS structure comprises patterning the MEMS substrate and removing portions of the first oxide release layer;
• bonding a cap wafer to a second surface of the MEMS wafer, the second surface of the MEMS wafer being opposite the first surface of the MEMS wafer, wherein bonding the cap wafer creates:
• a second cavity comprising the second portion of the polysilicon layer and the MEMS structure;
• and
• a third cavity, wherein a second surface of the first portion of the polysilicon layer is exposed to a pressure level of the third cavity;
• and
• exposing the first or the third cavity to an ambient environment.

A method for forming a micro-electromechanical (MEMS) device comprising:

• providing a MEMS wafer comprising a polysilicon layer;
• forming a sealed cavity over a first surface of a portion of the polysilicon layer, wherein a first surface of the portion of the polysilicon layer is exposed to a pressure level of the sealed cavity;
• and
• exposing a second surface of the portion of the polysilicon layer to an ambient pressure level, wherein forming the sealed cavity and exposing the second surface of the portion of the polysilicon layer comprises bonding a cap wafer and a carrier wafer to opposing surfaces of the MEMS wafer.