Trends in single event pulse widths and pulse shapes in deep submicron CMOS

Abstract

Single Event transients caused by incident charged particles on a semiconductor device, affect response of circuits in space applications. The shape of the transient pulse, especially the Full Width Half Max (FWHM) pulse width has important effects on the Single Event response of the circuit. Aggressive scaling in deep sub micron CMOS regimes has caused major changes in sequence and location of drift-diffusion events most important to the overall charge collection process, which results in a Single Event pulse shape that differs considerably from the shapes predicted by existing charge collection models. In this thesis, we use extensive TCAD (Technology Computer Aided Design) analysis to identify an electrostatic model explaining the observed pulse shapes. While the first half of this work deals with analysis and modeling of Single Event transient pulses based on circuit and contact boundary conditions, the second half looks at a pulse width mitigation technique based on the impact of the substrate doping profile on pulse shape. Some of the widest pulses in highly scaled CMOS are due to parasitic bipolar conduction. We demonstrate through TCAD modeling, the application of a novel buried layer scheme to reduce charge collection due to parasitic bipolar conduction - leading to truncation of some of the widest pulses.