Effects of irradiation induced lattice defects on standard trench and fine pattern trench IGBT characteristics

A comparison is made of irradiation damage in standard trench and fine pattern trench IGBTs (Insulated-Gate Bipolar Transistors) by 2-MeV electron irradiation at room-temperature. The electron fluence ranged from 1014 to 1015 e/cm2. Two different types of IGBTs are studied,with differences in trench depth, in trench width gate oxide thickness. For both types of devices the breakdown voltage is the same and 400 V. It is shown that in the range studied, the electron fluence dependency of the radiation-induced defects using deep-level transient spectroscopy (DLTS) and the voltage shift due to the radiation-induced interface traps (ΔVit) and the voltage shift due to the radiation-induced oxide traps (ΔVot) are different. From the difference in post-rad C-V characteristics it is derived that in one type of devices the B dopants become deactivated by H released by the high-energy electrons from the Phosphorus-Silicate-Glass (PSG) passivation layer.