Analytic Model of Threshold Voltage Variation Induced by Plasma Charging Damage in High-k Metal–Oxide–Semiconductor Field-Effect Transistor

Abstract

We discuss plasma charging damage (PCD) to high-k gate dielectrics and the resultant threshold voltage shift (ΔV th) in n-channel metal–oxide–semiconductor field-effect transistors (n-ch MOSFETs). The PCD induced by the antenna effect is focused on, and ΔV th and its variation are estimated for MOSFETs treated by various plasma processes. We propose a ΔV th variation model based on both the power-law dependence of ΔV th on the antenna ratio r (= exposed metal interconnect area/gate area) and the r distribution deduced from an interconnect-length distribution function (ILDF) in a large-scale integrated (LSI) circuit. Then, we simulate the variations in ΔV th [σ(ΔV th)] and the subthreshold leakage current I off [σ(I off)], in accordance with the employed r distribution. The model prediction quantitatively shows the effects of PCD on σ(ΔV th) and σ(I off): The antenna effect is found to increase σ(ΔV th) and σ(I off).

TDDB lifetime enhancement of high-k MOSFETs damaged by plasma processing — Conflicting results in plasma charging damage evaluation

“…2(b) indicates the relationship between the V th before plasma treatment and V th . This result implies that V th by PCD is independent of initial characteristics in contrast to the antenna effect as discussed previously [6,11]. high-k MOS capacitors, respectively.…”

“…However, one should keep in mind that, since plasma charging current inevitably degrades MOSFETs even if the antenna design rules are satisfied, there must be PCD behind data. In particular, it was pointed out [2,6] that the parameter variations of high-k MOSFETs built in an LSI may be enhanced by the distribution of interconnect lengths adopted in the circuit design called the Rent's rule [7,8]. Regarding high-k dielectrics, owing to characteristic charge trapping/detrapping mechanisms, it was also reported [9] that V th by PCD exhibits complicated behaviors, e.g., the direction of V th depends on the amount of PCD.…”