A DLTS study on Deep Trench Processing induced Trap States in Silicon Photodiodes

Deep Trench Isolation (DTI) is commonly employed to separate individual devices or different blocks on a monolithic semiconductor chip. However, trap states at the DTI sidewalls may impact the performance of minority carrier based devices by means of interface recombination. To extract parameters of traps located at or nearby the DTI sidewalls we perform a Deep Level Transient Spectroscopy (DLTS) study on dedicated test structures. Furthermore, we exploit the trap parameters in computer simulations to evaluate the influence of sidewall trap states on the performance of DTI-terminated island photodiodes. Our results suggest that the carrier recombination at the DTI interface states is responsible for a non-linear diode behavior with respect to the optical radiant flux.