Charakterisierung und Optimierung selektiv gewachsener vertikaler Silizium-MOS-Feldeffekttransistoren

Characterization and Optimization of Selectively Grown Vertical Si-MOS Transistors The subject of this thesis was the process development, characterization and optimization of silicon based MOS field-effect transistors. The active transistor region was grown using selective epitaxy. Two different layouts have been investigated and optimized in respect of their electrical characteristics. For one of them (V-FET) only weIl established self-aligning standard technology is used, where the gate oxide is obtained by oxidation of the epitaxially grown transistor stack. For the radio frequency optimized layout (VOXFET) the stack is grown after the deposition of the gate oxide. This leads to a reduction of overlap capacitances while the channel-togate self-alignment is lost. p-channel transistors with channel lengths between 100 nm and 200 nm and gate oxide thicknesses of 6 nm - 10 nm showed transconductances up to 200 mS/mm. The subthreshold slope turned out to be 11.5 mV I dec. Radio frequency measurements on optimized VOXFETs showed cut-off frequencies up to 20 GHz. These are the highest cut-off frequencies reported for vertical MOSFET up to now