Multiscale Computational Analysis of the Interaction between the Wafer Micro-Topography and the Film Growth Regimes in Chemical Vapor Deposition Processes

摘要

The deposition limiting step during the chemical vapor deposition (CVD) process of a film can be identified by the Arrhenius plot, which shows the effect of the wafer temperature on the deposition rate. The deposition limiting step, and as a consequence the Arrhenius plot, are affected by the operating conditions of the CVD reactor. By using a multiscale computational framework, it is shown that they are also affected by the existence of a micro-topography (e.g. micro-trenches) on the wafer. The origin of this effect is the loading phenomenon and the mutliscale computations are used to quantify it: The deposition rate decreases in the diffusion limited regime; the latter and the transition regime are shifted at lower temperatures compared to the flat wafer case. The evolution of the deposited film profile in the micro-trenches is calculated at all deposition regimes. The film conformity starts to decrease when the wafer temperature exceeds the maximum temperature of the reaction limited regime. Finally, it is shown that the effect of the micro-topography on the species concentrations in the reactor bulk is important only in the transition regime. The case studies are CVD of a) tungsten from tungsten hexafluoride and b) silicon from silane.