PIN DETECTOR ARRAYS AND INTEGRATED READOUT CIRCUITRY ON HIGH-RESISTIVITY FLOAT-ZONE SILICON

A new silicon PIN-diode-based pixel detector for ionizing particles in tegrating a two-dimensional array of detecting elements with readout c ircuitry has been developed and extensively tested. The signal charge is collected on a low-capacitance electrode avoiding loss of charge in to the local readout circuitry within each pixel. The spatial resoluti on for a given circuitry size is optimized. The approach required back side patterning of the wafer, the only nonconventional part in the St anford BiCMOS based manufacturing process. Thirteen masks on the front side of the wafer and three on the back yielded both CMOS readout cir cuitry and detecting elements. A gettering step helped obtain a high m inority carrier lifetime (500 mus). Test results [1] obtained by infra red illumination [2], gamma rays [3], [4], and high-energy particles [ 5]-[7], which have been described in detail elsewhere, will be summari zed. They include a signal to single-channel-noise performance of abou t 150 to 1 for a minimum ionizing particle, which is an order of magni tude better than silicon strip detectors currently used, and a record- breaking spatial resolution in the direction of smallest pixel pitch ( standard deviation of about 1.8 mum). We describe the device and chip operation of the new detector in detail.