Influence of pixel topology on performances of CMOS APS imagers

This paper describes a 128x128 pixels prototype array organized as sub-arrays of 32x32 pixels each, with 21 mu m pixel pitch. The sub-arrays, photodiode or photogate based, are implemented using a standard 0.7 mu m CMOS process. Various topologies of the photosensitive area have been implemented and some of them have an optical metal shield over the so-called non-sensitive area to evaluate the contribution of the active electronic area to the responsivity of the sensor. A synthesis of the measurements carried out by CIMI-SUPAERO and MMS, addressing darkness parameters, noise, photometric and radiometric performances, are presented with emphasis on the photogate type pixels. Results of spot-scan analysis and crosstalk measurements performed on selected topologies are also reported. Several samples were irradiated at different proton doses and their related behavior is discussed. From these results, a new 512x512 pixels array has been designed for space applications. The main features of this APS device are presented here.