Improvement of pattern effect by optical-absorption carbon film and flexibly-shaped-pulse flash lamp annealing

We have developed a carbon absorber process to reduce the pattern effect. This process consists of deposition of carbon, flash lamp annealing (FLA) in an oxygen ambient and SPM-APM wet cleaning. The feature of this process is that the carbon absorber equalizes the light absorption from flash lamps macroscopically and microscopically on the annealed wafer. As a result, we can suppress the pattern effect such that the uniformity of Rs in a 40mm × 40mm area is improved from 11.4 % to 2.1 %. Additionally this process can achieve higher activation than that without the carbon absorber process. We also demonstrate that a flexibly-shaped-pulse FLA (FSP-FLA) can suppress the pattern effect to give a uniformity of 3.4 %. By combining the carbon-absorber process with FSP-FLA, we can achieve 1.6 %. This Rs uniformity of the pattern effect is comparable to that of sRTA.