410K pixel PtSi Schottky-barrier infrared CCD image sensor

摘要

We developed an 811 by 508-element monolithic focal plane array detector using a PtSi Schottky-barrier photodiode, which has the greatest number of pixels for the Standard TV format. This detector array uses an interlined CCD configuration and 1.0-micron design rules. The pixel size of this detector was 18 by 21 microns square. From many experiments, the process conditions needed for obtaining the high responsivity were determined. To obtain high responsivity, we focused on two important aspects. The first one was an effective fill factor, and the second one was the properties of the PtSi Schottky barrier. Applying the new procedure to the wafer fabrication process, we reduced the nonactive portion of the pixel and obtained the ideal optical cavity structure. This new procedure was also a damage-free process, so good PtSi Schottky-barrier properties were obtained, which is related to the second aspect. We investigated the dependence of Schottky-barrier height on Pt deposition substrate temperature. Based on the results of the investigation, typical $Phi b (Schottky- barrier height) and typical C$-1$/ (quantum efficiency coefficient) of 0.22 eV and 0.28/eV, respectively, were obtained. The NETD (noise equivalent temperature difference), calculated as the ratio of noise to response, was 0.06 K. The responsivity nonuniformity was estimated to be 0.45%. These measurements were done for a scene temperature of 300 K, f/1.2 cold shield, a 3 micrometer- long-wavelength pass filter, and 1/60-second integration time. Excellent thermal imaging was obtained without uniformity correction. We also show that the combination of electrical shutter operation and ND filter is suitable for high-temperature measurement.