Advanced activation and stability of ultra-shallow junctions using flash-assisted RTP
Advanced-logic device technology for the 65 nm node and beyond requires highly-activated, shallow, and abrupt dopant profiles (Int. Technol. Roadmap for Semicond., 2003). The combination of ion implantation and an advanced annealing technology is expected to provide solutions for these requirements. In contrast to spike annealing, a diffusion-less but highly activating, high-temperature, flash-assisted RTP annealing approach for the formation of ultra-shallow junctions will be demonstrated. The flash-assisted RTP technique is a promising method for achieving junction depth and sheet resistance values low enough to meet the performance specifications for the 65 nm node and beyond (Gelpey, et al., 2002, McCoy, et al., 2004). The optimal process for high activation during flash-assisted RTP involves a temperature ramp-up to an intermediate temperature between 700degC and 900degC and, once the intermediate temperature is reached, a very short, intense flash on the front side of the wafer induces a temperature jump up to 1325degC with a peak width of approximately 1.6 ms in a 100 ppm oxygen in nitrogen gaseous ambient. In this paper, we will present some of our recent p+MOS and n+MOS results on the fabrication of ultra-shallow junctions using flash-assisted RTP in crystalline and pre-amorphized silicon. It will be shown that such junctions are suitable for future technology generations. The measured "mechanical/electrical" sheet resistance values of the junctions are compared to Hall measurements on the same samples to gain an insight into the reliability of the destructive four-point probe (4PP) method for such extremely shallow junctions. Deactivation studies will be presented to examine the stability of the process to the required subsequent thermal processes
Influence of nucleation on the kinetics of boron precipitation in silicon
A study of the precipitation of boron implanted into pre-amorphized silicon has been carried out following several thermal processes in the temperature range between 550 and 900 °C. It will be shown that the formation of inactive boron takes place even during a low-temperature solid-phase epitaxy of the regrowing layer, when the starting concentration level exceeds about 3.5×1020 atoms/cm3. The presence, at the beginning of the annealing process, of inactive atoms in the form of small aggregates which behave as nucleation centers, markedly affects the precipitation kinetics during the thermal treatments. In these conditions the experimental data follow the Ham's theory of precipitation. On the contrary, if all the dopant is incorporated in the lattice side, nucleation is the limiting factor for boron deactivation.
An analysis of patients discharged from a hospital‐based glaucoma case‐finding clinic over a 3‐year period
Purpose:  To analyse the false positive referrals by community optometrists to a glaucoma case‐finding clinic over a 3‐year period.