Monolithic Active Pixel Sensors (MAPS) in a quadruple well technology for nearly 100% fill factor and full CMOS pixels

TL;DR

This paper introduces a novel quadruple well CMOS process called INMAPS, enabling nearly 100% fill factor and full CMOS pixels for particle physics sensors, with improved charge collection efficiency.

Contribution

The development of a quadruple well process in 0.18μm CMOS technology that enhances charge collection and allows complex pixel designs for particle physics applications.

Findings

Significant improvement in charge collection efficiency.

Successful fabrication of high-density CMOS pixels.

Effective screening of N-wells from the epitaxial layer.

Abstract

In this paper we present a novel, quadruple well process developed in a modern 0.18mu CMOS technology called INMAPS. On top of the standard process, we have added a deep P implant that can be used to form a deep P-well and provide screening of N-wells from the P-doped epitaxial layer. This prevents the collection of radiation-induced charge by unrelated N-wells, typically ones where PMOS transistors are integrated. The design of a sensor specifically tailored to a particle physics experiment is presented, where each 50mu pixel has over 150 PMOS and NMOS transistors. The sensor has been fabricated in the INMAPS process and first experimental evidence of the effectiveness of this process on charge collection is presented, showing a significant improvement in efficiency.