Network Model Analysis of Poly-silicon Film Deposition on Wafers in CVD Reactor

We studied a simple reaction analysis technique using a network model (NM) to calculate the concentration distribution and deposition rate in a vertical hot-wall-type low-pressure chemical vapor deposition (LPCVD) reactor. We analyzed the deposition rates of poly-silicon film. The calculation results of the deposition rate using the NM analysis agreed with those of the FEM analysis within the difference of 10%. The computation of the NM analysis was 1000 times faster than that of the FEM analysis, indicating that the NM analysis model is effective for shortening computation time without increasing computation error. In semiconductor processing, low-pressure chemical vapor deposition (LPCVD) process is indispensable to fabricate deposition films on wafers with a good step coverage rate. Most LPCVD processes are carried out in a batch-type furnace, where a row of many wafers is heated in a vertical hot-wall-type furnace at the same time, thus ensuring a high production rate. In order to fabricate thin films uniformly on wafers for high-density VLSI devices, it is important to know the concentration distribution of the process gas and the deposition rate of the film in the reactor by numerical simulation. It takes a long time to calculate the concentration distribution and the deposition rate in the reactor using a conventional numerical simulation code with the finite element method (FEM) or the finite differential method (FDM) because the flow velocity, the temperature, the concentration of the gas, and the chemical reaction at multiple node points must be calculated at the same time. In this work, we propose a simple simulation technique to calculate the concentration distribution and the deposition rate in the reactor using the network model (NM) in a vertical hot-wall-type LPCVD reactor to shorten the computation time without increasing computation errors.