MEMS-mirror based trajectory resolution and precision enabled by two different piezoresistive sensor technologies

Two new technological process flows for the piezoresistive position detection of resonant and quasistatic micro scanning mirrors were developed to increase sensitivities by a factor of 3:6 compared to former sensors, improve signal to noise ratio of the sensor signal and to allow controlled feedback loop operation. The sensor types use differently doped and deposited silicon. One is based on single crystal silicon with a pn-junction to isolate the active sensor area from the device layer silicon, the other one is based on a deposited and structured polysilicon. The sensor characteristics are compared including light, temperature dependence and reliability results.