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Impedance matching controller for an inductively coupled plasma chamber: L-type Matching Network Automatic Controller

Bacelli, Giorgio and Ringwood, John V. and Iordanov, Petar (2007) Impedance matching controller for an inductively coupled plasma chamber: L-type Matching Network Automatic Controller. In: ICINCO 2007, 4th International Conference on Information in Control, Automation and Robotics, 9 - 12 May, 2007, Angers, France. (Unpublished)

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Abstract

Plasma processing is used in a variety of industrial systems, including semiconductor manufacture (deposition and etching) and accurate control of the impedance matching network is vital if repeatable quality is to be achieved at the manufacturing process output. Typically, impedance matching networks employ series (tune) and parallel (load) capacitors to drive the reflection coefficient on the load side of the network to zero. The reflection coefficient is normally represented by real and imaginary parts, giving two variables to be controlled using the load and tune capacitors. The resulting problem is therefore a nonlinear, multivariable control problem. Current industrial impedance matching units employ simple single-loop proportional controllers, which take no account of interaction between individual channels and, in many cases, may fail to tune altogether, if the starting point is far away from the matching point. A hierarchical feedback controller is developed which, at the upper level, performs a single-loop tuning, but with the important addition of a variable sign feedback gain. When convergence to a region in the neighbourhood of the matching point is achieved, a dual single-loop controller takes over, which gives fine tuning of the matching network.

Item Type: Conference or Workshop Item (Paper)
Keywords: Automatic impedance matching; Matching network; Impedance sensor; Inductively coupled plasma.
Subjects: Science & Engineering > Electronic Engineering
Item ID: 1426
Depositing User: Professor John Ringwood
Date Deposited: 08 Jun 2009 16:26
Refereed: Yes
URI:

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