Monitoring Arsenic In-Situ Doping with Advanced Models for Poly-Silicon CVD

Experiments of As-doped poly-silicon deposition have shown that under certain process conditions step coverages > 1 can be achieved. We have developed a new model for the simulation of As-doped poly-silicon deposition, which takes into account surface coverage dependent sticking coefficients and surface coverage dependent As incorporation and desorption rates. The additional introduction of Langmuir type time-dependent surface coverage enabled the reproduction of the bottom-up filling of the trenches. In addition the rigorous treatment of the time-dependent surface coverage allows to trace the in-situ doping of the deposited film. Simulation results are shown for poly-Si deposition into 0.1 μm wide and 7 μm deep, high aspect ratio trenches.