Application of exhaustive simulation flow for advanced performance prediction of monolithic active pixel sensors

TL;DR

This paper introduces a comprehensive simulation flow for advanced performance prediction of monolithic active pixel sensors, integrating detailed electrical and charge propagation models to improve accuracy.

Contribution

The paper presents a novel simulation approach combining TCAD, Allpix Squared, and SPICE to accurately model MAPS performance, including irradiation effects.

Findings

Simulation results agree with measurements for TJ-Monopix2.

The methodology enhances understanding of pixel characteristics under irradiation.

The approach supports development of high-precision MAPS for particle detectors.

Abstract

Monolithic active pixel sensor (MAPS) developments have pushed the detection performance in various directions, especially relative to timing where nanosecond-level precision is now considered. This evolution calls for a simultaneous upgrade of the simulation tools. We have developed a simulation flow that covers steps from the signal creation in the sensitive volume to the output of the pixel digital logic that performs the time-of-arrival and time-over-threshold (ToA/ToT) measurements. This approach adds several new features to the traditional use the of the TCAD - Allpix Squared duo, among which : the integration of the pixel wells from the layout in order to precisely describe the pixel key characteristics such as leakage and punch-through currents and the coupling of Monte Carlo simulations (Allpix Squared) with high precision electrical simulations (SPICE). The first (Allpix Squared) for the precise description of the current induced at the collection electrode and the second (SPICE) to guarantee high precision simulation of the front-end electronics using realistic signal events. Irradiation is also modeled, both from the charge propagation side (charge trapping) and from the front-end response side (high input signal discharge). We have applied this methodology to the MAPS developed in the context of the Belle II vertex detector upgrade. In this contribution, we detail the key features of the exhaustive simulation flow, present the outcome of the comparison with the TJ-Monopix2 measurements and discuss the interest of the methodology for the development of modern MAPS.