Multidimensional optimisation of process parameters by experimental designfor the deposition of aluminium and silicon oxynitride films with predictable composition

In this study the deposition of aluminium and silicon oxynitride films by r eactive d.c. magnetron sputtering is systematically planned by design of ex periments, carried out and evaluated with the application of specialised st atistics software. With these sample applications it is shown that statisti cal process modelling is a modern tool for process description and optimisa tion with the outstanding opportunity to gain fast and precise control of a technological process. The influence of the deposition parameters, such as working and reactive gas flow and sputtering power, on the concentration o f oxygen, nitrogen and aluminium or silicon in the resulting films is evalu ated. With the obtained data a model for the quantitative prediction of the deposition parameters necessary to obtain films with desired composition w as built. This is demonstrated by a confirmatory experiment. This is also o f technological importance, since the physical properties of the films depe nd strongly on their composition. With the help of this procedure the sampl e position, which was not expected to be of any relevance, could be discove red as an influential process parameter. Consequently, design of experiment s can be a valuable problem solving technique. Furthermore. the flexibility of the statistical model is demonstrated by implementing the degree of pro cess long-term repeatability into the model and, in addition, by excluding two deposition parameters with a lesser degree of significance and calculat ing the prediction accuracy of a process operating under this less complica ted general condition. (C) 1999 Elsevier Science S.A. All rights reserved.