Shallow source/drain extension formation using antimony and indium pre-amorphization schemes for 0.18- to 0.13-μm CMOS technologies

Abstract

Pre-amorphization scheme has been widely used to form shallow source/drain (SID) extension for deep sub-micron CMOS technology [1-3}. In this paper, different Sb and In implantation conditions (various implant energies and doses) were used before BF2 and As HDD implant to study their effects on pMOS and nMOS characteristics, respectively, such as L_ (the gate length at I0=1nMjm at Vg=O, IVdIl.5V), Icjrive (diive current when VgIIVdIL5\O, and diode leakage. These characteristics will also be compared with those obtained from devices without the pre-amorphization. TEOS 1 spacer in different thickness and various final RTA temperatures were also used to study their effect on the drive current.The key results are as follows.(1) A 4% improvement in Ijve(stong) (from 185A/m to 193A4im; the drive current at I0=1nA/p.m at supplying voltage of 1.5V and t,39A) and '-O.O2m reduction in L (from -O. 16gm to -o. 14gm) were observed for the pMOS devices with Sb pre-amorphization when the same thickness of the 1st spacer was used. These improvements are due to the formation of a more shallow and abrupt HDD when pre-amorphization is used.(2) With the requirement of L= '-O. 16tm, a p-channel Ijve(strong)21 1j.iA/tm at O. 16xm were obtained with a thin 1St spacer and with Sb pre-amorphization in this study. For the same Lj requirement, a thick 1st spacer (150A thicker than the thin one) had to be used for a device without the pre-amorphization, which resulted in a higher Rd and thus degraded the drive current to Ijve(strong)=185A/prn. (3) The Sb implant conditions do not form an effective pocket implant doping for either case studied. A similar improvement in L_ is observed for different annealing temperatures studied. (4) In contrast to the L_ of a pMOS, the junction diode leakage is sensitive to the Sb implant condition. The diode leakage increases with Sb implant energy and dose. (5) Contrary to the Sb pre-amorphization cases, no significant improvement in either Lirive dL is observed in the nMOS devices with In pre-amorphization.