Determination of interface state density in MOSFETs using the spatial profiling charge pumping technique

This paper presents a modified charge-pumping technique, called the spatial profiling charge pumping (SPCP) technique, that is used to determine the spatial distribution of the interface state density NIT in MOSFETs. Using this technique, the spatial variation of NIT was determined independently near the source and drain without assumptions on the channel spatial distribution of NIT. Results show that the interface state distribution of a virgin MOSFET studied was not constant along the channel, but the NIT spatial profile is very dependent on the device processing details. For devices from the same processing group, NIT shows a similar spatial profile, but its magnitude varies slightly from device to device. Increases in NIT were found near the drain junction edge after hot-carrier injection stress.