Characterization of charge trapping in SiO/sub 2//HfO/sub 2/ dielectrics

Abstract

The techniques for characterizing HfO/sub 2/ charge traps are summarized in this paper. A defect band is present in the HfO/sub 2/ layer and located above the Si conduction band. This band can be efficiently charged and discharged by applying positive or negative gate bias respectively. The effect of the defect band can be observed by I/sub D/-V/sub G/ characteristic. It is concluded from experiments that only the electron fluence controls the trapping, while the detrapping is controlled by oxide field in combination with the lattice temperature. Charge pumping is proven to be a suitable technique to measure the charge trapping in SiO/sub 2//HfO/sub 2/ stacks. The trap density can be scanned by varying the gate pulse amplitude or in distance from the Si/SiO/sub 2/ interface by varying the pulse frequency.