Compact enhanced sensitivity temperature sensor using an encapsulated clamped-clamped MEMS beam resonator

A micro-electrical-mechanical (MEMS) temperature sensor, comprising:

• a cavity wafer configured with an air cavity region, wherein the air cavity region is defined by cavity sides and a bottom surface;
• a metal layer located on the bottom surface of the air cavity region;
• a membrane wafer located over the cavity wafer, wherein the membrane wafer is configured with:
• a microbeam, the microbeam having a first end and a second end, wherein the microbeam is located over the air cavity region;
• a first anchor attached to the first end;
• a second anchor attached to the second end;
• a drive electrode located on a substrate on a first side of the microbeam near the first end;
• a sense electrode located on the substrate at a second side of the microbeam near the second end;
• a first ground electrode adjacent to the drive electrode on the first side near the second end;
• a second ground electrode adjacent to the sense electrode on the second side near the first end;
• a first metallic feed line connected at a first terminal to the drive electrode and at a second terminal to a first side electrode pad;
• a second metallic feed line connected at a first terminal to the first anchor and at a second terminal to a second side electrode pad;
• a third metallic feed line connected at a first terminal to the second ground electrode and at a second terminal to a third side electrode pad;
• a fourth metallic feed line connected to a fourth side electrode pad;
• a fifth metallic feed line connected at a first terminal to the sense electrode and at a second terminal to a fifth side electrode pad;
• a sixth metallic feed line connected at a first terminal to the second anchor and at a second terminal to a sixth side electrode pad;
• a seventh metallic feed line connected at the first terminal to the second ground electrode and at a second terminal to a seventh side electrode pad;
• wherein each of the side electrode pads are adjacent to one another and parallel to the microbeam;
• a capping wafer located over and encapsulating the cavity wafer and membrane wafer, wherein the side electrode pads are exposed;
• an aluminum layer configured to cover a periphery of the MEMS temperature sensor, while leaving the side electrode pads exposed;
• an alternating current (AC) source connected to the first side electrode pad;
• a DC bias voltage source connected to the second side electrode pad;
• a ground connected to the third side electrode pad, the fourth side electrode pad, the sixth side electrode pad and the seventh side electrode pad;
• wherein the microbeam is configured to vibrate at a resonant frequency related to a temperature surrounding the MEMS temperature sensor when an AC current is applied to the drive electrode and a DC bias voltage is applied to the first anchor, wherein the sense electrode is configured to capacitively sense the vibration and generate an induced current based on the resonant frequency;
• a multimeter connected to the fifth side electrode pad, wherein the multimeter is configured to measure the induced current;
• and
• a computing device connected to the multimeter, wherein the computing device is configured with a display and a database including records relating induced current values to temperature values, wherein the computing device is configured to search the database to match the induced current to a temperature value and display the temperature value on the display.