Optimization of N/P Performance Matching through Adjusting Extension Region Doping Concentration for Vertical Gate-All-Around FETs

A novel vertical gate-all-around FET (VGAAFET) structure based on the Si/SiGe/Si/SiGe/Si epitaxial stacks is proposed for integrating the controllable gate and spacer lengths, as well as self-aligned junctions. In the proposed VGAAFET structure, SiGe layers served as extension regions form the doping pocket between the Si source/drain (S/D) and Si channel in pFET due to the higher solid solubility of boron in SiGe. Optimization of the doping concentration in the pFET extension regions has been demonstrated to enhance the saturation current of the pFET by 23% and improve the n/p current ratio from 1:0.74 to 1:0.91 when compared to undoped extension regions. To further investigate the performance improvement of the VGAAFET-based ring oscillator (RO) by adjusting the doping concentration in the extension regions, the design-technology co-optimization (DTCO) platform is established. An enhancement of 17% in frequency and a reduction of 12% in energy-delay product (EDP) have been achieved when the doping concentration of the pFET extension regions is the same as that of the S/D.