Multi-Scale Simulation of Radiation Effects in Electronic Devices

As integrated circuits become smaller and more complex, it has become increasingly difficult to simulate their responses to radiation. The distance and time scales of relevance extend over orders of magnitude, requiring a multi-scale, hierarchical simulation approach. This paper demonstrates the use of multi-scale simulations to examine two radiation-related problems: enhanced low-dose-rate sensitivity (ELDRS) in bipolar transistors and single-event effects (SEE) in CMOS integrated circuits. Examples are included that demonstrate how information can be passed from simulation tools operating at one level of abstraction to those operating at higher levels, while maintaining accuracy and gaining insight.

I. Introduction

Changes in microelectronic materials and device structures have resulted in very significant changes to integrated-circuit technologies in recent years. These changes have the potential to affect radiation hardness in dramatic and unexpected ways. Energy deposition, carrier generation, carrier transport, charge trapping, and defect formation depend on the materials used in the ICs. Sensitivity to the electrostatic effects of radiation-induced trapped charge, including device-edge and inter-device leakage currents, depends on the detailed device geometries and doping profiles. Single-event effects change with scaling, including effects such as multiple-bit upsets and complicated angular effects. This paper discusses simulation-based approaches for analyzing radiation effects in advanced technologies, emphasizing multi-scale simulations that are based on detailed physical modeling of radiation interactions and carrier transport. Two major categories of radiation effects are considered: long-term and transient.