Uniform spike anneals of ultra low energy boron implants using xR LEAP and RTP Centura XE/sub plus/: ramp rate effects up to 150/spl deg/C/sec

In order to form junctions shallower than 0.1 /spl mu/m required for the source/drain extensions for 0.18 /spl mu/m technology and beyond, boron ions have been implanted in pre-amorphised Si at 1 keV and doses of 1E14-1E15 cm/sup -2/ using an Applied Materials xR LEAP ion implanter. Implanted wafers were subsequently annealed in an RTP Centura to /spl sim/1 sec soak time and to temperatures between 1000-1100/spl deg/C. Ramp up rates between 75/spl deg/C/s and 150/spl deg/C/s were examined. Junctions with depths between 40-80 nm (taken at 1E17 cm/sup -3/ SIMS B concentration) can be formed routinely with sheet resistance tuneable between 300-900 /spl Omega///spl square/ using Ge pre-amorphisation, and subsequent spike annealing at ramp up rates of 150/spl deg/C/sec in nitrogen atmosphere. It was found that sheet resistance (Rs) is most dependent on the spike anneal temperature, while the ramp up rate appear to have a minimal effect on reducing Rs or controlling junction depth (/spl chi//sub j/). The oxygen content in the RTA ambient is an important parameter in controlling both Rs and /spl chi//sub j/. The crystallinity of the spike annealed wafers has been evaluated using high resolution transmission electron microscopy (HRTEM).