Analysis of Interface States between Plasma‐CVD Silicon Nitride and Silicon‐Substrate Using Deep‐Level Transient Spectroscopy

Deep‐level transient spectroscopy (DLTS) has been employed to measure interface state density, at the interface of plasma chemical vapor‐deposited silicon nitride and a silicon‐substrate interface, using metal‐insulator‐semiconductor (MIS) diodes. The DLTS signal‐height increases with increasing emission pulse voltage in the negative direction. This finding is remarkable, especially for the silicon‐rich film, This is equivalent to a capacitance‐voltage hysteresis effect in the MIS diodes. The three major DLTS signals originating from the interface states are observed for each case of silicon‐rich, stoichiometric, and silicon‐poor films, It is shown that the electrons trapped at the interface states are emitted with several emission time constants. The minimum , , at the midgap, is obtained for a N/Si atomic ratio of near‐stoichiometric composition, A decrease in excess silicon and nitrogen atoms is effective for the reduction of .