Sensor with an embedded thermistor for precise local temperature measurement
A resistive temperature sensor (thermistor) for a microelectromechanical system (MEMS) device provides local temperatures of MEMS sensors and other MEMS devices for temperature compensation. Local accurate temperatures of the sensors and other devices provide for temperature compensation of such sensors or devices. By incorporating the thermistor structure into a MEMS device, an accurate temperature is sensed and measured adjacent to or within the structural layers of the device. In one embodiment, the thermistor is located within a few micrometers of the primary device.
1. A microelectromechanical system (MEMS) device comprising:
a substrate;
a silicon layer having an upper surface;
a first dielectric layer disposed between the substrate and the silicon layer;
a thermistor structure disposed in the silicon layer, the thermistor structure being configured to extend from the dielectric layer to the upper surface of the silicon layer; and
a device structure disposed in one of the silicon layer and the dielectric layer.
2. The MEMS device of claim 1 wherein the thermistor structure comprises a resistive structure including a plurality of dielectric columns extending from the dielectric layer toward the surface of the silicon layer, wherein each of the plurality of dielectric columns is separated from another of the plurality of dielectric columns by a portion of the silicon layer.
3. The MEMS device of claim 2 further comprising a plurality of contacts disposed on the silicon layer, each of the plurality of contacts being subtended by the silicon layer and at least one of the plurality of dielectric columns.
4. The MEMS device of claim 3 wherein the silicon layer includes a first silicon layer and a second silicon layer, and further including a second dielectric layer disposed between the first and second silicon layers, the second dielectric layer being connected to at least two of the plurality of the dielectric columns.
5. The MEMS device of claim 4 further comprising a third dielectric layer laterally disposed on the second silicon layer, wherein the plurality of dielectric columns extend from the first dielectric layer to the third dielectric layer.
6. The MEMS device of claim 5 wherein the third dielectric layer includes a plurality of trenches configured to expose a surface of the second silicon layer and wherein the plurality of contacts contact the exposed surface of the second silicon layer.
7. A microelectromechanical system (MEMS) sensor for sensing a device condition of a MEMS device, the MEMS sensor comprising:
a functional layer formed of silicon wherein the silicon includes the MEMS device; and
a resistive structure disposed in the functional layer adjacent to the MEMS device, the resistive structure including a plurality of dielectric spacers disposed in the functional layer to define the resistive structure.
8. The MEMS sensor of claim 7 , wherein the plurality of dielectric spacers are disposed in the functional layer to define the resistive structure such that the resistance of the resistive structure varies in response to a change in temperature.