Large area hybrid detector technology based on amorphous silicon photosensors

Abstract

A technological approach for the fabrication of large area hybrid detectors is presented. The proposed hybrid detector consists in an array of hydrogenated amorphous silicon photodiodes directly connected to a CMOS readout chip, which is vertically integrated over the sensor array using flip-chip bonding. In particular, the proposed solution relies on a stack of interconnection layers, deposited on top of the photodiode array, to route each individual pixel output to a separate pre-amplifier channel. This avoids the need for a geometrical matching between the sensor array and the chip contact pads. As a consequence, conventiona non-pixelated readout chip can be used and easy-scalable large area detectors can be produced. Furthermore the sensor array and the readout chip can be optimized independently leading to additional advantages as fast readout, implementation of in-pixel signal conditioning and pre-processing and superior noise performances. Experimental results validating all the technological steps involved in the fabrication of the hybrid detector are reported in detail.