Single gate 0.15 μm CMOS devices fabricated using RTCVD in-situ boron doped Si/sub 1-x/Ge/sub x/ gates

Abstract

Single gate 0.15 CM CMOS devices have been successfully fabricated using in-situ boron doped polycrystalline Si/sub 1-x/Ge/sub x/ (poly-Si/sub 1-x/Ge/sub x/) as the gate material for both surface channel n- and p-MOSFETs. The p/sup +/ poly-Si/sub 1-x/Ge/sub x/ gate electrodes were deposited by rapid thermal chemical vapor deposition using a Si/sub 2/H/sub 6/, GeH/sub 4/, B/sub 2/H/sub 6/ and H/sub 2/ gas mixture. The experimental results showed that the developed single gate process provides a minimized poly-depletion effect and boron penetration. By changing the Ge content in the poly-Si/sub 1-x/Ge/sub x/ films from x=0.3 to 0.76, a threshold voltage (V/sub T/) adjustment of about 0.3 V was achieved with the same channel doping and gate oxide thickness. Computer simulations indicate that an improved current drive and transconductance can be achieved in p/sup +/ poly-Si/sub 1-x/Ge/sub x/ gate devices compared to poly-Si gate devices with a fixed V/sub T/. This work demonstrates a potentially promising approach for deep submicron single gate bulk CMOS technology.