DC and RF characterization of NiSi Schottky barrier MOSFETs with dopant segregation

The continuous downscaling of the Si-based microelectronics, which is the fundament of today’s information technology, requires novel concepts for the source/drain (S/D) architecture of metal-oxide-semiconductor field-effect transistors (MOSFETs). The improvement of the carrier injection is of prime importance because of the increasing impact of parasitic resistances which strongly limit the performance of ultimately scaled transistors. Moreover, steeper junctions at the contact/channel interfaces become more and more crucial for nanoscale devices. In this context, Schottky-barrier (SB) MOSFETs with metallic S/D are promising performance boosters since they offer low extrinsic resistances and atomically abrupt junctions formed at the metal/silicon interface. However, a drawback of these devices is their performance which is inferior to conventional MOSFETs due to the relatively high Schottky barrier. Recently, dopant segregation has attracted much interest since the highly doped layer formed at the silicide/silicon interface during silicidation strongly improves the tunneling probability of carriers through Schottky contacts. The present thesis studies the integration of NiSi with dopant segregation in SBMOSFETs on thin-body silicon-on-insulator experimentally. The objective of the detailed direct-current (DC) and radio-frequency (RF) characterization is to gain a better insight into the physics of these devices. The modeling of NiSi/p-Si Schottky contacts using a numerical model which combines the thermionic emission theory with image-force induced barrier lowering and quantum-mechanical tunneling provides a solid understanding of the carrier injection of Schottky contacts. The characterization of Schottky diodes with silicidation induced dopant segregation using boron, arsenic and antimony reveals effective Schottky barrier heights in the 0.1 eV regime depending on the implantation dose. Below this value SB-MOSFETs are capable of outperforming conventional MOSFETs. Successfully fabricated long- and short-channel p- and n-type SB-MOSFETs with and without dopant segregation are characterized performing direct-current (DC) measurements. Transistors with 80 nm channel length reveal on-currents as high as 427 μA/μm for p-type and 1150 μA/μm for n-type devices, respectively, which compete well with state-of-the-art SB-MOSFETs. [...