Article ID Journal Published Year Pages File Type
1676912 Thin Solid Films 2006 6 Pages PDF
Abstract

We have investigated theoretically the cause of the substantial threshold voltage (Vth) shifts observed in Hf-related high-k gate stacks with p+poly-Si gates, by focusing on the ionic nature of HfO2. The oxygen vacancy (Vo) level in ionic HfO2 is located in a relatively higher part of the band gap. This high position of the Vo level results in a significant elevation of the Fermi level for p+poly-Si gates, if the p+poly-Si gate is in contact with the high-k HfO2. Vo formation in the HfO2 induces a subsequent electron transfer across the interface, causing a substantial Vth shifts in p+poly-Si gate MISFETs. Moreover, our theory also systematically reproduces other recent experimental results.

Related Topics
Physical Sciences and Engineering Materials Science Nanotechnology
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