Minimization of specific contact resistance in multiple gate NFETs by selective epitaxial growth of Si in the HDD regions

High parasitic S/D resistance is a major obstacle in realizing future generations of CMOS technologies using multiple gate FETs with narrow fins. Reduction of specific contact resistance by selective epitaxial growth of Si in heavily doped S/D regions of a multiple gate FET helps with achieving low S/D resistance. This paper addresses integration of low temperature selective epitaxial growth process into multiple gate FET processing. Our experimental results show more than 30% reduction in the parasitic S/D resistance for 16-nm selective epitaxial growth of Si in the heavily doped S/D regions of multiple gate NFETs with less than 20-nm wide fins. A follow up of this work with HfO2-TiN gate stack shows more than 20% improvement in the drive current at a constant IOFF for 40-nm selective epitaxial growth of Si in the heavily doped S/D regions of multiple gate FETs.