Simulation of Boron-doped Silicon Film Thickness within Holes on the Wafer

Abstract

A reaction model is discussed for in-situ boron-doped silicon chemical vapor deposition that uses Si 2 H 6 and B 2 H 6. First, the elementary reactions were studied by using an ab initio molecular orbital method and theˆrst-principle molecular dynamics method. These showed that the B 2 H 6 decomposes into BH 3 easily and that BH 3 has a high probability of sticking to siliconˆlm. Therefore, the boron was doped in the siliconˆlm by BH 3. The desorption energy of H 2 terminated siliconˆlm surface was lower due to the boron doping in the siliconˆlm. Then, an increase in the boron concentration of the siliconˆlm increased the sticking probability of the Si 2 H 6. Next, a deposition model was made on the basis of these results, and reaction constants were determined by using experimental results. Final-lyˆlm thickness distribution was simulated by using a ‰ow-diŠusion-reaction analysis and an integrated method on the above deposition model. The result shows that our reaction model can replicate experimental step coverage.