The paper investigates the method of improving deposition rate in semiconductor deposition process, while maintaining film thickness uniformity and step coverage in a vertical LPCVD (Low-Pressure Chemical Vapor Deposition) system. In general increasing pressure improves deposition rate, but it decreases uniformity of thickness. The result of experiment and the numerical simulation showed that the non-uniformity of film thickness in high-pressure condition can be improved by controlling flow patterns in the space between wafers. In the molecular flow region (low pressure), the deposition rate and the step coverage were not influenced by the source gas flow rate. In the viscous flow region (high pressure), the step coverage can be improved by increasing source gas flow rate. For the flow the nozzle design and exhaust port location are important. Installation of rings outside of wafers is also effective for the improvement of thickness uniformity.
