Real-time virtual metrology and control for plasma etch

Lynn, Shane and MacGearailt, Niall and Ringwood, John (2012) Real-time virtual metrology and control for plasma etch. Journal of Process Control, 22. pp. 666-676. ISSN 0959-1524

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Plasma etch is a semiconductor manufacturing process during which material is removed from the surface of semiconducting wafers, typically made of silicon, using gases in plasma form. A host of chemical and electrical complexities make the etch process notoriously difficult to model and troublesome to control. This work demonstrates the use of a real-time model predictive control scheme to control plasma electron density and plasma etch rate in the presence of disturbances to the ground path of the chamber. Virtual metrology (VM) models, using plasma impedance measurements, are used to estimate the plasma electron density and plasma etch rate in real time for control, eliminating the requirement for invasive measurements. The virtual metrology and control schemes exhibit fast set-point tracking and disturbance rejection capabilities. Etch rate can be controlled to within 1% of the desired value. Such control represents a significant improvement over open-loop operation of etch tools, where variances in etch rate of up to 5% can be observed during production processes due to disturbances in tool state and material properties.

Item Type: Article
Keywords: Virtual metrology; Plasma etch; Predictive functional control; Electron density; Etch rate; Advanced process control;
Academic Unit: Faculty of Science and Engineering > Electronic Engineering
Item ID: 3867
Depositing User: Professor John Ringwood
Date Deposited: 17 Sep 2012 11:42
Journal or Publication Title: Journal of Process Control
Publisher: Elsevier
Refereed: Yes

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