HIGH ENERGY HEAVY-ION-INDUCED SINGLE EVENT TRANSIENTS IN EPITAXIAL STRUCTURES*

This paper describes numerical and experimental heavyion charge collection studies using PfN junctions on epitaxial layers. The numerical simulations provide insights into the basic mechanisms contributing to transient currents and charge collection in devices on epitaxial layers. This paper also presents charge collection data from -2 GeV lZ7I ions incident upon PfN junctions on both bulk silicon and epitaxial layers and compares the experimental data with the simulation results. The experimental data show that charge deposited below the epitaxial layer can be collected. This work is unique and important because this GeV-energy-range 1271 ion more nearly represents a cosmic ray compared to lower energy, heavy-ions in the hundreds of MeV energy range. This paper also discusses the simulation results with respect to the experimental data and charge collection models for epitaxial transistors. Additionally, a shunting model is proposed to model the early transient current responses. I. INTRODUCTION Placing devices in epitaxial layers on highly doped substrates provides one method for reducing single event effects in microcircuits. The relatively thin epitaxial layer on top of a highly doped substrate serves to reduce the available charge collection volume for device upset and latchup. The highly doped substrate also reduces spreading resistance thereby raising latchup holding and triggering currents [ 11.