Single gate 0.15μm CMOS devices fabricated using RTCVD in-situ boron doped Si1-xGex gates

Single gate 0.15 mu m CMOS devices have been successfully fabricated using in-situ boron doped polycrystalline Si1-xGex(poly-Si1-xGex) as the gate material for both surface channel n- and p-MOSFETs. The p(+) poly-Si1-xGex gate electrodes were deposited by rapid thermal chemical vapor deposition using a Si2H6, GeH4, B2H6 and H-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-Si1-xGex films from x=0.3 to 0.76, a threshold voltage (V-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(+) poly-Si1-xGex gate devices compared to poly-Si gate devices with a fixed V-T. This work demonstrates a potentially promising approach for deep submicron single gate bulk CMOS technology.