Low temperature wafer level processing for MEMS devices

A method comprising:

• providing a first substrate comprising:
• a silicon wafer;
• at least one feed-through through a thickness of the first substrate from a first surface to a second surface providing electrical interconnection by way of the at least one feed-through from the first surface to the second surface, the at least one feed-through comprising:
• an electrically conductive material covering a predetermined region of the sidewall of the at least one feed-through;
• and
• a second non-conductive material filling the remaining interior region of the at least one feed-through to a predetermined depth from the second surface to the first surface and having a maximum temperature exposure to the substrate during manufacturing of at least one of 250° C. and 350° C.;
• and
• at least one microelectromechanical systems (MEMS) device directly onto the second surface of the first substrate and electrically connected to the at least one feed-through;
• providing a second substrate comprising:
• a borosilicate wafer;
• and
• at least one recess dimensioned so as to accept the at least one MEMS device fabricated on the first substrate;
• pre-processing the first and second substrates by:
• removing silicon oxide from first predetermined regions of the first substrate to be bonded to the second substrate by a dry etching process;
• exposing second predetermined regions of the second substrate to be bonded to the first substrate to a chemical process to create silanol bonds on said second predetermined regions of the second substrate;
• positioning the second substrate with respect to the first substrate such that the at least one MEMS device is thereby contained within a cavity formed by the first substrate and the at least one recess;
• and
• bonding the second substrate and first substrate together by forming silicon-oxygen-silicon bonds via an evaporation process utilizing a pressure annealing sequence.