Study of low frequency noise in High Voltage MOS transistor

Abstract

HVMOSFETs find many different applications such as switching applications, input-output operations, voltage conversions, RF amplification etc. The effect of drift region on 1/f noise remained unclear until recently due to the difficulty of performing 1/f noise measurements under high drain voltages, on the order of tens of Volt. This is mainly due to the lack of adequate measurement equipment, which usually restricts low frequency noise to be measured up to just a few Volt, usually generated from batteries.

A 1/f noise parameter extraction method for high-voltage (HV-)MOSFETs at 3V drain bias is presented in this thesis. In this region the overall noise is mostly dominated by the noise originating in the channel. The bias dependence of flicker noise, related to transconductance-to-current ratio, allows for an easy means to determine related noise parameters. Though measured data is limited, parameters related to carrier number fluctuation effect may be found. 50 V N and P-channel HV-MOSFETs are investigated for long as well as short channel lengths. The parameter extraction method is applied to a recently established 1/f noise model for HV-MOSFETs, showing a good agreement among model and experimental data.