A Recipe Map for the processing window in BCl sub 3/Cl sub 2 plasma etching of aluminum.

This paper describes a quantitative Recipe Map which has been constructed to target the controllable gas flows, wafer loading, and temperature settings which are predicted to result in the optimum BCl sub 3/Cl sub 2 plasma etching of fine line Aluminum for a given reactor and background oxygen pressure. The numerical predictions of this Recipe Map are based on modelling the plasma as a steady state flow system in which all thermodynamically predicted chemical reactions are occurring with collision limited kinetics, and where there is, in addition, physical sputtering which can remove material from the ion-bombarded surfaces. Anisotropic etching is caused by the sputtering of deposited B sub 2 O sub 3 which allows the chemical etching of the underlying Aluminum. Although this model is very simple, its numerical predictions are in good qualitative agreement with the processing window for the BCl sub 3/Cl sub 2 plasma etching of Aluminum which is observed in the large volume, slow residence time, non-load-locked plasma processing systems in use today.