The SIA roadmap predicts that junction depths of 500 angstroms are required for CMOS technology nodes of 0.18 #mu#m or beyond by the year 2001. There are several ultra-shallow junction doping techniques currently under investigation. These include beamline ion implantation, plasma immersion ion implantation, and gas immersion laser doping. This study was based on beamline ion implantation of B, P, and As into single-crystal Si wafers at 0.25-2 keV to doses of (2-10)x10~(14) at./cm~2 with minimized beamenergy contamination. Rapid thermal annealing was applied to the implanted wafers at 1000-1050 deg C for 10-15 sec at ramp rates of 35-50 deg C/s in a N_2 ambient. Transient enhnaced diffusion was observed for all three implant species. For example, the depth of 0.25 keV B measured by SIMS increases from 250 to 520 A at a concentration level of 1x10~(17) at./cm~3 upon RTA. To minimize the TED, several schemes of defect engineering were applied prior to low energy implantation, including pre-amorphization and implantation of other species. A comparison of TED for different implantation conditions is given with the aim of process development for minimizing TED. The impact of energy contamination on ultra shallow junctions is also addressed.
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