Characterization of Fully Depleted CMOS Active Pixel Sensors on High Resistivity Substrates for Use in a High Radiation Environment

TL;DR

This paper reports on the development and testing of a depleted CMOS active pixel sensor prototype on high-resistivity substrates, optimized for high-radiation environments like the HL-LHC, demonstrating effective charge collection and radiation tolerance.

Contribution

It introduces a novel DMAPS prototype fabricated on high-resistivity substrate with full depletion at low voltage and integrated fast readout, suitable for high-radiation applications.

Findings

Full depletion at around 20V voltage

Radiation tolerance up to 50 Mrad and 10^15 neq/cm^2 fluence

Successful integration of sub-pixel decoding for fast readout

Abstract

Depleted CMOS active sensors (DMAPS) are being developed for high-energy particle physics experiments in high radiation environments, such as in the ATLAS High Luminosity Large Hadron Collider (HL-LHC). Since charge collection by drift is mandatory for harsh radiation environment, the application of high bias voltage to high resistive sensor material is needed. In this work, a prototype of a DMAPS was fabricated in a 150nm CMOS process on a substrate with a resistivity of >2 k{\Omega}cm that was thinned to 100 {\mu}m. Full depletion occurs around 20V, which is far below the breakdown voltage of 110 V. A readout chip has been attached for fast triggered readout. Presented prototype also uses a concept of sub-pixel en/decoding three pixels of the prototype chip are readout by one pixel of the readout chip. Since radiation tolerance is one of the largest concerns in DMAPS, the CCPD_LF chip has been irradiated with X-rays and neutrons up to a total ionization dose of 50 Mrad and a fluence of 10E15neq/cm2, respectively.