System and method for voltage-based plasma excursion detection
First Claim
1. A method for detecting plasma excursions in a plasma chamber, comprising:
- directly sensing a bias voltage from a radio frequency (RF) powered electrode disposed in a gas distribution system within the plasma chamber during plasma processing;
filtering the bias voltage using a plurality of analog filters to obtain an output voltage signal;
comparing the output voltage signal to a preset voltage value that represents a plasma excursion event; and
generating an alarm signal if the output voltage signal exceeds the preset voltage value.
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Abstract
The present invention provides a system and method for the detection of plasma excursions, such as arcs, micro-arcs, or other plasma instability, during plasma processing by directly monitoring direct current (DC) bias voltage on an RF power electrode of a plasma processing chamber. The monitored DC bias voltage is then passed through a succession of analog filters and amplifiers to provide a plasma excursion signal. The plasma excursion signal is compared to a preset value, and at points where the plasma excursion signal exceeds the preset value, an alarm signal is generated. The alarm signal is then fed back into a system controller so that an operator can be alerted and/or the processing system can be shut down. In certain embodiments, multiple processing regions can be monitored by a single detection control unit.
58 Citations
18 Claims
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1. A method for detecting plasma excursions in a plasma chamber, comprising:
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directly sensing a bias voltage from a radio frequency (RF) powered electrode disposed in a gas distribution system within the plasma chamber during plasma processing; filtering the bias voltage using a plurality of analog filters to obtain an output voltage signal; comparing the output voltage signal to a preset voltage value that represents a plasma excursion event; and generating an alarm signal if the output voltage signal exceeds the preset voltage value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for detecting plasma excursions in a plasma chamber, comprising:
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one or more voltage probes, each voltage probe configured to attach to a radio frequency electrode within a gas distribution system in a plasma chamber and sense a bias voltage of the radio frequency electrode during plasma processing; and a plasma excursion detection unit, comprising; one or more excursion detection modules, wherein each excursion detection module is configured to receive the bias voltage from one of the one or more voltage probes, wherein each excursion detection module comprises a plurality of analog filters arranged to filter the bias voltage to obtain an output voltage signal, and wherein each excursion module further comprises a comparator configured to compare the output voltage signal to a preset voltage signal and generate an alarm signal if the output voltage signal exceeds the preset voltage signal; one or more connection ports configured to receive the preset voltage signal from a host controller and configured to send the alarm signal to the host controller; and a data acquisition module configured to collect and transfer the output voltage signal from each of the one or more excursion detection modules to a data logging and diagnostic system. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification