METHODS AND APPARATUS FOR CONTROLLING A PLASMA PROCESSING SYSTEM
First Claim
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1. A method for controlling a plasma processing system operating using multiple RF frequencies, comprising:
- obtaining an RF voltage signal from an RF sensing mechanism via a high impedance path;
processing said RF voltage signal to obtain a plurality of signals, said plurality of signals including at least individual signals corresponding to individual ones of said multiple RF frequencies;
inputting said plurality of signals into a transfer function; and
providing an output of said transfer function as a control signal to control at least a subsystem of said plasma processing system.
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Abstract
A method and apparatus for compensating a bias voltage at the wafer by measuring RF voltage signals in RF driven plasma including at least an electrostatic, chuck (ESC), a capacitive divider, a signal processing and signal conditioning network is disclosed. The bias compensation device includes a capacitive divider to detect the RF voltage at the ESC, a signal conditioning network for the purpose of filtering specific RF signals of interests, and a signal processing unit for computing the DC wafer potential from the filtered RF signals.
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Citations
21 Claims
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1. A method for controlling a plasma processing system operating using multiple RF frequencies, comprising:
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obtaining an RF voltage signal from an RF sensing mechanism via a high impedance path; processing said RF voltage signal to obtain a plurality of signals, said plurality of signals including at least individual signals corresponding to individual ones of said multiple RF frequencies; inputting said plurality of signals into a transfer function; and providing an output of said transfer function as a control signal to control at least a subsystem of said plasma processing system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A plasma processing system configured for processing at least one wafer disposed on an electrostatic chuck (ESC), comprising:
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an RF sensing mechanism, said RF sensing mechanism is sufficiently proximate to a non-plasma exposing component of said ESC to obtain an RF voltage signal; a high impedance arrangement coupled to said RF sensing mechanism to facilitate acquisition of said RF voltage signal while reducing perturbation of RF power driving a plasma in said plasma processing system; a signal processing arrangement configured to receive said RF voltage signal and to apply one of a digital and analog version of said RF voltage signal to a transfer function to obtain a transfer function output; and an ESC power supply subsystem configured to receive said transfer function output as a feedback signal to control said plasma processing system during processing of said at least one wafer. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification