METHODS AND APPARATUS FOR DETECTING THE CONFINEMENT STATE OF PLASMA IN A PLASMA PROCESSING SYSTEM
First Claim
1. A method for detecting plasma unconfinement in a plasma processing chamber, said plasma processing chamber having an electrostatic (ESC) chuck, comprising:
- providing an RF voltage to said ESC chuck;
providing a ESC power supply unit configured to provide a DC bias voltage to said ESC chuck, said ESC power supply unit having a center tap coupled to receive said RF voltage;
simultaneously monitoring said RF voltage and said center tap for changes indicative of a plasma unconfinement condition; and
providing a signal to indicate a presence of said plasma unconfinement condition if said plasma unconfinement condition is detected by said monitoring.
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Abstract
Methods and systems for detecting a change in the state of plasma confinement within a capacitively coupled RF driven plasma processing chamber are disclosed. In one or more embodiments, the plasma unconfinement detection methods employ an analog or digital circuit that can actively poll the RF voltage at the powered electrode in the form of an Electrostatic Chuck (ESC) as well as the open loop response of the power supply (PSU) responsible for chucking a wafer to ESC. The circuit provides a means detecting both a change in RF voltage delivered to the ESC as well as a change in the open loop response of the PSU. By simultaneously monitoring these electrical signals, the disclosed algorithm can detect when plasma changes from a confined to an unconfined state.
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Citations
20 Claims
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1. A method for detecting plasma unconfinement in a plasma processing chamber, said plasma processing chamber having an electrostatic (ESC) chuck, comprising:
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providing an RF voltage to said ESC chuck; providing a ESC power supply unit configured to provide a DC bias voltage to said ESC chuck, said ESC power supply unit having a center tap coupled to receive said RF voltage; simultaneously monitoring said RF voltage and said center tap for changes indicative of a plasma unconfinement condition; and providing a signal to indicate a presence of said plasma unconfinement condition if said plasma unconfinement condition is detected by said monitoring. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An arrangement for detecting plasma unconfinement in a plasma processing chamber, said plasma processing chamber having an electrostatic (ESC) chuck, said ESC chuck being configured to receive an RF voltage, comprising:
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a ESC power supply unit configured to provide a DC bias voltage to said ESC chuck, said ESC power supply unit having a center tap coupled to receive said RF voltage; and means for analyzing said RF voltage and an open-loop DC response on said center tap for changes indicative of a plasma unconfinement condition. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification