Design of monolithic visible light / IR CCD focal plane array

Abstract

Recently, more and more attention has been paid on the multispectral imaging for its excellent resolution capability in the complex environment. For this reason, various sensors for multispectral imaging has been developed. Generally, these sensors contain a visible light Focal Plane Array for visible light imaging and an IR Focal Plane Array for IR imaging with the CCD or CMOS readout circuit to output the signal. In this paper, a novel monolithic visible light (400nm-800nm) / IR (1μm-5μm) charge coupled device (CCD) focal plane array sensor was designed. This sensor was fabricated using 2 micron design rule and a double level poly silicon with four phase transfer structure. The especial design of the device was that it integrated the visible light sensitive cells and IR sensitive cells on a single chip with the PN junction photodiode for the visible light signal detecting and the PtSi Schottky-barrier diode for the IR signal detecting. The number of PN junction photodiode and PtSi Schottky-barrier diode arrayed in offset intersection were all 512(H)×256(V), so the hole number of the pixels were 512(H)×512(V). The device was operated in interleaved scanning mode, the visible light signal and IR signal was exported in odd filed and even field respectively. This sensor was an interline-transfer CCD with an on-chip amplifier which was used to read out the video at 12.5 MHz to provide standard 30 frames per second format. The test result shows that this sensor was succeed in visible light / IR multispectral imaging worked at the temperature of 77K. Visible light / IR CCD Focal Plane Array has an excellent potential application foreground for its wide spectral response. It can be replaced the two separated systems for visible light imaging and IR imaging. For this reason, it can be decreased the complexity of the camera system and reduced the cost.