Monolithic uncooled infrared image sensor with 160 by 120 pixels

This paper presents the key design features of an uncooled infrared image sensor with 160 by 120 pixels. This sensor has a monolithic structure using micromachining technology. These features concern the configuration of the readout circuit, the structure of the infrared detector, and the thermal isolation structure in a pixel. The first feature is a simple readout circuit that includes neither an amplifier nor a switching transistor in the pixel. The second feature is the use of a thin film resistive bolometer made of polysilicon as the infrared detector. The detector has a P+-P--N+ diode structure which operates as a bolometer and cuts off current passes through non-selected pixels. The forward resistance of the diode can be tailored by adjusting the shape and impurity concentration of the P- region. Finally, a microbridge structure for the thermal isolation is made in each pixel by using the micromachining technology. The bolometer is monolithically integrated on this structure. Since polysilicon is generally used in the conventional Si-LSI process, this choice of detector material makes it possible to manufacture the image sensor using only current Si-LSI facilities, and realize a low cost uncooled infrared camera.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.