A Transient Analysis Method to Characterize the Trap Vertical Location in Nitride-Trapping Devices

A new method to probe the trap vertical location for nitride-trapping devices is proposed. This method requires only measuring the time dependence of gate injection at various gate voltages on a single wafer. The transient current (J) and the instantaneous electric field (E) across the top oxide can be directly obtained based on various cases of trap location. Comparisons can be made to check which case has the best consistency for the J versus E behaviors. The only assumption in this method is that the transient current J and the instantaneous E field should follow a consistent tunneling relationship at different gate voltages. The experimental results show unequivocally that electrons are trapped at the interface between top oxide and nitride for oxide grown by thermal conversion. However, for the direct-deposited top oxide the electrons are more spatially distributed in the nitride. This method is a simple and convincing tool to detect the nitride trap vertical location.