Solar panels produced via the thin-film deposition process are efficient and small. The thin-film deposition technique allows for a “roll-to-roll” production process that maximizes throughput and minimizes material overhead. Depending on the type of film to be deposited (and the substrate) the technique can be physical vapor deposition (PVD), chemical vapor deposition (CVD), or plasma-enhanced CVD (PECVD). Regardless of the technique, a residual gas analyzer (RGA) can be used to provide process information over a wide range of pressures, typically from 5 Torr to 10e-5 Torr. This information is crucial for both manufacturing quality and quantity.
In its simplest form, an RGA is used to monitor the thin-film line during pump down and is the perfect early warning system for deposition line problems. At the completion of the deposition run, the deposition tool undergoes a preventive maintenance cleaning process to remove deposits from the walls of the chamber. Following this, offline post-preventive maintenance requalification takes place as the tool is pumped down to process operating conditions.
An RGA can tell you not only the total pressure of the residual gas in the chamber, but also the gas species present and their partial pressures. Developing pump-down curves for different deposition chambers is done by creating baseline data for key gas species present in the chamber (e.g. N2, O2, H2O, and many cleaning solvents). By using statistical process control methodology to help characterize these variables, pump-down curves can be used as a reliable early warning system to inform maintenance personnel of vacuum problems before significant time is lost trying to achieve base pressure. The result is more time spent making product rather than recovering from preventive maintenance servicing.
For more information about this application and AMETEK’s RGA solution, refer our application note, “Optimizing Solar Panel Production with the Dycor LC-D Residual Gas Analyzer.”