Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 65: Devices
HL 65.3: Talk
Wednesday, April 2, 2014, 12:00–12:15, POT 151
RF- and DC Characterization of the High-k to InGaAs Interface in Gate Last nMOSFETs — •Guntrade Roll, Mikael Egard, Sofia Johansson, Erik Lind, and Lars-Erik Wernersson — EIT, Lund University, Lund, Sweden
InGaAs MOSFETs are a promising candidate for low power and high-frequency application. Due to high-injection velocity and mobility it is possible to reach high on-currents at low source/drain voltages. An improved high-k to channel interface quality and low source/drain resistance are challenges currently under research. We have developed a gate last nMOSFET process flow, which gives an excellent extrinsic transconductance of 1.9mS/µm (LG=55nm) and a source/drain resistance of 199Ω/µm. The presentation will focus on the evaluation of InGaAs/Al2O3/HfO2 interface quality, using RF and DC characteristics. A hopping gate leakage via defects to the transistor raised source/drain is observed. Prestress border defects are filled by trapping when the transistor is turned on. This leads to a transconductance frequency dispersion and current-voltage hysteresis. Reliability is a key issue for all future technologies. The degradation after constant gate stress and hot carrier stress is analyzed. The border trap density is increased by constant gate stress. The threshold bias shift due to trapping is the main reliability problem, which has to be overcome by further improving the high-k processing.