Drain currents and their excess noise in triple gate bulk p-channel FinFETs of different geometry

Abstract

The drain current I, spectral density of the low-frequency 1/f noise SI and transconductance gm of triple gate bulk p-channel field-effect transistors (FinFETs) fabricated on 200mm diameter Cz silicon wafers have been studied in the standard (ST) and Dynamic Threshold Voltage (DT) modes of operation. For the ST regime, a sub-linear increase of the drain current I with increasing overdrive voltage |Vov| and practically no changes in the spectral density SI of the noise are observed at high values of |Vov|. The effect is attributed to a sub-linear increase of the free hole density in the channel, whereby the mobility does not change with increasing |Vov|. An increase of the values of I, SI and gm normalized for the device geometry with increasing Leff is found and is attributed to the decrease of the mobility degradation coefficient with increasing Leff. For the DT regime of operation, the decrease of the threshold voltage |Vth| is not accompanied by an increase of the drain current which decreases with increasing |VGF| due to the high leakage current passing through the forward biased drain and source junctions. However, that decrease of the drain current is not accompanied by changes in the value of SI.