In-depth exploration of Si-SiO2 interface traps in MOStransistors using the charge pumping technique

Abstract:  Abstract It is shown that the charge pumping (CP) technique can be used for extraction of the depth concentration profile of traps situated in the oxide of metal-oxide-semicond uctor (MOS) transistors, near and at the Si-SiO2 interface. The trap density is obtained from the variation of the charge pumping current as a function of frequency, the other measurement parameters being kept constant. The concentration profiles are measured on n and p-channel transistors from several technologies, and on virgin and stressed devices. The results show that the trap concentration decreases rapidly from the Si-SiO2 interface in the direction of the oxide depth and suggest that it becomes constant at a fraction of a nanometer from the silicon interface. The method easily demonstrates the trap creation due to Fowler-Nordheim stress. The profiles compare favorably with those measured using a new drain-current transient technique. In all cases, the integration of the depth concentration profiles leads to the interface trap densities measured using the conventional charge pumping method