Optimization of the plasma sputtering deposition processing by computational fluid dynamics

The uniformity of the deposited film in the sputtering process is a key issue that determines the quality of the device and the fabrication yield. Geometric parameters as well as operating conditions are considered as two major categories that are responsible for the film uniformity. The parameters of reactor geometries in the first category include the dimensions and size of the reactor, the distance between target and substrate, and locations for the inlet gas and exhaust gas. The second category, (operating conditions), includes the factors such as gas flow rate, operating pressure, types of energy provided, quantities of energy given. Therefore, it is a tedious and costly procedure to fine-tune these variables to achieve the optimal film uniformity. In this study, the usage of CFD (computational fluid dynamics) techniques accompanied with the DOE (design of experiment) and ANN (artificial neural network, back propagation feed-forward neural net) methods is implemented to help locate the best parameters for plasma sputtering deposition process. In conclusion, the most significant factor that affects the film uniformity and deposition rate is voltage of the target; the second most significant factor is operation pressure, while the flow rate of input gas has the least effect. With respect to the effect of target voltage, it is found that this variable has a much greater influence on the deposition rate than its effect to the film uniformity.