Real-time Virtual Metrology and Control of Plasma Electron Density in an Industrial Plasma Etch Chamber
Lynn, Shane and MacGearailt, Niall and Ringwood, John (2011) Real-time Virtual Metrology and Control of Plasma Electron Density in an Industrial Plasma Etch Chamber. Proceedings of 18th IFAC World Congress . pp. 12060-12065. ISSN 1474-6670
Plasma etching is a semiconductor manufacturing process during which material is removed from the surface of silicon wafers using gases in plasma form. A host of chemical and electrical complexities make the etch process notoriously dicult to model and troublesome to control. This work demonstrates the use of a real-time model predictive control scheme to maintain a consistent plasma electron density in the presence of disturbances to the ground path of the chamber. The electron density is estimated in real time using a virtual metrology model based on plasma impedance measurements. Recursive least squares is used to update the controller model parameters in real time to achieve satisfactory control of electron density over a wide operating space.
Repository Staff Only: item control page