DMAPS: a fully depleted monolithic active pixel sensor—analog performance characterization

Abstract

Monolithic Active Pixel Sensors (MAPS) have been developed since the late\n1990s based on silicon substrates with a thin epitaxial layer (thickness of\n10-15 $\\mu$m) in which charge is collected on an electrode, albeit by\ndisordered and slow diffusion rather than by drift in a directed electric\nfield. As a consequence, the signal is small ($\\approx$ 1000 e$^-$) and the\nradiation tolerance is much below the LHC requirements by factors of 100 to\n1000. In this paper we present the development of a fully Depleted Monolithic\nActive Pixel Sensors (DMAPS) based on a high resistivity substrate allowing the\ncreation of a fully depleted detection volume. This concept overcomes the\ninherent limitations of charge collection by diffusion in the standard MAPS\ndesigns. We present results from a test chip EPCB01 designed in a commercial\n150 nm CMOS technology. The technology provides a thin (50 $\\mu$m) high\nresistivity n-type silicon substrate as well as an additional deep p-well which\nallows to integrate full CMOS circuitry inside the pixel. Different matrix\ntypes with several variants of collection electrodes have been implemented.\nMeasurements of the analog performance of this first implementation of DMAPS\npixels will be presented.\n