Failure Analysis and Radiation-Enabled Circuit Simulation of a Dual Charge Pump Circuit

Dual charge pump data show a reduction of circuit output voltage with dose. Through testing of individual process monitors, the response is identified as parasitic interdevice leakage caused by trapped oxide charge buildup in the isolation oxide. A library of compact models is generated for the field oxide parasitic based on test structure data along with 2-D structure simulation results. The charge pump schematic is then back annotated with transistors representative of the parasitic at different dose levels. Inclusion of the parasitic devices in schematic allows for simulation of the entire circuit at a specific dose. The reduction of circuit output with dose is then re-created in simulation.