FORMATION OF SIGE SOURCE DRAIN USING GE IMPLANTATION FOR FLOATING-BODY EFFECT RESISTANT SOI MOSFETS

SiGe was formed by Ge implantation into silicon on insulator (SOI) sub strates with the dosage range from 0.5 to 3 x 10(16) cm(-2) and subseq uent annealing in N-2. The implantation dosage dependence of the cryst alline quality bandgap and sheet resistance of the SiGe layers are inv estigated. The implantation damage for Ge dosage up to 1 x 10(16) cm(- 2) can be removed at a temperature as low as 700 degrees C. A SiGe cry stalline network is formed by the annealing at the same time. With a G e dosage of 1 x 10(16) cm(-2) or more, bandgap narrowing of the SiGe l ayer was detected. Sheet resistances of SiGe N+ and P+ layers graduall y increase for higher Ge dosage. SOI MOSFET characteristics in terms o f the floating-body effect with the SiGe source/drain layers are prese nted. The bandgap narrowing suppresses the floating-body effect of ful ly depleted SOI MOSFETs, while maintaining the reverse leakage current of the p-n junction between the source/drain and channel at a low lev el.