Multiscale analysis of silicon low-pressure chemical vapor deposition

We consistently performed computer fluid dynamics (CFD) analysis in a reactor (macroscale analysis) and deposition profile analysis on a submicron hole (microscale analysis) for Si low-pressure chemical vapor deposition (LPCVD). For the gaseous phase and the surface reaction of the SiH4 source gas, we adopted the dominant reaction model, which involved two intermediates, SiH2 and Si2H6, and was based on the Kleijn Model. We analyzed the fluid flow, heat transfer and chemical reactions throughout the entire batch-type reactor, and estimated the Si growth rate, gaseous species concentration, and relative contributions of SiH4, SiH2 and Si2H6 to Si growth. Moreover, the Si-filling profile on a submicron hole was predicted by topography simulation in which the parameters were the growth rate, the relative contribution and the sticking coefficient of each species. The relationship between the relative contribution of SiH2, which has a high sticking coefficient, to Si growth and the hole-filling capability was quantitatively clarified from the results of a combination of the two analyses. The hole-filling capability at the wafer edge was deteriorated by the influence of SiH2 gas produced in the decomposition of Si2H6 gas, which was diffused from outside the wafer. This effect became considerable with increasing temperature. Reducing the wafer pitch will be effective in improving the hole-filling capability because both the SiH2 generation reaction in the region between wafers and SiH2 gas diffusion from outside the wafer will be inhibited.