Modeling gas by-products from MO-CVD thin-film depositions

This work seeks to develop an MO-CVD system using in situ sensors and automated process control to deposit controlled, reproducible oxide fiber coatings (e.g. LaAl/sub 11/O/sub 18/). A CVD system capable of continuous fiber coating has been assembled which employs liquid precursor delivery for precise precursor stoichiometry control and inert gas seals for near atmospheric operation. In-situ thermocouples and a mass spectrometer are used for process measurements. All of the system parameters are logged by and controllable by computer. A fuzzy logic controller was developed to control the flow rate based on the desired temperature or gas composition. A neural model of the process will be presented which translates the process settings into expected gas compositions.