Development of Monolithic Active Pixel Sensor in SOI Technology fabricated on the wafer with thick device layer

Abstract

Monolithic active pixel detectors fabricated in SOI (Silicon On Insulator) technology are novel sensors of ionizing radiation, which exploit SOI substrates for the integration of readout electronics and a pixel detector. The fully depleted sensing diode has been manufactured under buried oxide (BOX) while read-out circuitry occupies upper silicon layer (‘device layer’). The development of the SOI detectors of ionizing radiation was started as a part of the SUCIMA project. During the project, it was proved that a monolithic SOI detector is a viable option for high-energy physics and medicine. The early prototypes suffered from significant leakage currents and soft breakdowns. These effects limited yield of production. Moreover, the p-wells (formed within the device layer and extended to the interface with the BOX), caused some local potential wells below the BOX at the top of depleted sensor area reducing the effective charge collection efficiency. The use a thicker device layer and optimized technology appeared to be a remedy.