Surface-micromachined pyroelectric infrared imaging array withvertically integrated signal processing circuitry

摘要

Surface-micromachining techniques have been used in thenfabrication of a 64×64 element PbTiO3 pyroelectricninfrared imager. Polysilicon microbridges of 1.2 Μm-thickness havenbeen formed 0.8 Μm above the surface of a silicon wafer. Each of then4096 polysilicon microbridges measures 50×50 Μm2 andnforms a low thermal mass support for a 30×30 Μm2nPbTiO3 pyroelectric capacitor with a thickness of 0.36 Μm.nThe air-bridge formed reduces the thermal conduction path between thendetector element and substrate. An NMOS preamplifier cell is locatedndirectly beneath each microbridge element. The measured blackbodynvoltage responsivity at 30 Hz is 1.2×104 V/W. Thencorresponding measured normalized detectivity (unamplified) D* isn2×108 cm-Hz1/2W at 30 Hz. The test chipnfabricated measures 1×1 cm2 and contains more than tennthousand transistors and 4096 micromechanical structures with integratednferroelectric microsensors. The technique of stacking of microsensorsnand integrated circuits represents a new approach for achievingnhigh-density and high-performance integrated pyroelectric microsensorsnthrough minimization of circuit to sensor interconnection with extremelynsmall thermal crosstalk