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Ultra Thin Body SB-MOSFET

As MOSFETs are scaled down to nanometer dimensions, metallic source/drain Schottky barrier (SB) MOSFETs are regarded as an alternative to conventional MOSFETs which require low resistive contacts and abrupt doping profiles. SB-MOSFETs satisfy these requirements because of their metallic contacts and atomically abrupt source and drain (S/D) junctions at the metal-silicon interface. However, SB-MOSFETs exhibit an intrinsic performance inferior to conventional MOSFETs due to the Schottky barriers which build up at the metal-channel interfaces. In order to meet the ITRS roadmap requirements at the 22 nm node and beyond, the Schottky barrier height (SBH) has to be less than 0.1 eV. No metal can achieve this low SBH value on Si. SBH engineering based on NiSi and epitaxial NiSi2 is very interesting to reduce the effective SBH. One of the SBH engineering methods is to introduce a very thin and highly doped layer beneath the NiSi layer. This layer can be formed either by an implant-to-silicide (ITS) process and subsequently followed by a low temperature annealing to form small S/D extensions, or by silicidation induced dopant segregation (SIDS). SB-MOSFETs with dopant segregated silicide S/D show highly improved performance.

Presently, we are working on the following topics:
•Fabrication of short-channel (<20nm) SB-MOSFETs
•Investigation of new silicide materials and ultra thin silicide layers.
•Investigation of the high frequency response (S-Parameter) of Schottky- Barrier MOSFETs to elucidate the carrier injection mechanism in ultrashort gate length transistors.
•Investigation of silicidation and SIDS in nanowires to realize Schottky barrier NW-FET with gate all around.

SB-MOSFETA 20nm gate length SB-MOSFET on SOI with epitaxial NiSi2 S/D

SB-MOSFETA 80nm gate length n-type SB-MOSFET with As dopant segregated NiSi S/D, showing very high Ion

SB-MOSFETMeasured cut-off frequency of As and B dopant segregated NiSi S/D SB-MOSFETs as a function of gate length, showing good scaling of the transistor