Methods for control of plasma transitions in sputter processing systems using a resonant circuit
First Claim
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1. A method for DC-plasma processing comprising:
- supplying power to a plasma vessel with a power supply, to ignite a plasma in the plasma vessel;
measuring current across a resonant circuit that is in electrical communication with an output of the power supply;
measuring voltage across the resonant circuit;
detecting that a plasma arc is imminent prior to arc initiation by determining that a linear voltage drop has occurred over a time duration for which current is substantially constant based on the measured current and measured voltage; and
controlling a switch in parallel with the output of the power supply to shunt current away from the plasma prior to arc initiation to increase energy stored in the resonant circuit to extinguish the plasma in response to conditions leading to an arc, and controlling the switch to direct the energy stored in the resonant circuit to the input of the power supply when the conditions leading to an arc are stopped, wherein energy stored in the resonant circuit from shunting current away from the plasma can reignite the plasma after the plasma is extinguished.
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Abstract
Methods and apparatus for controlling a plasma used for materials processing feature cooperative action of a resonant circuit and a switch unit coupled to a plasma vessel and a power supply. A sensor for acquiring a signal associated with a state of a plasma in the plasma vessel supports closed-loop control of the switch unit. Undesirable plasma states detected by the sensor can be eliminated by closing the switch unit to shunt the resonant circuit.
110 Citations
5 Claims
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1. A method for DC-plasma processing comprising:
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supplying power to a plasma vessel with a power supply, to ignite a plasma in the plasma vessel; measuring current across a resonant circuit that is in electrical communication with an output of the power supply; measuring voltage across the resonant circuit; detecting that a plasma arc is imminent prior to arc initiation by determining that a linear voltage drop has occurred over a time duration for which current is substantially constant based on the measured current and measured voltage; and controlling a switch in parallel with the output of the power supply to shunt current away from the plasma prior to arc initiation to increase energy stored in the resonant circuit to extinguish the plasma in response to conditions leading to an arc, and controlling the switch to direct the energy stored in the resonant circuit to the input of the power supply when the conditions leading to an arc are stopped, wherein energy stored in the resonant circuit from shunting current away from the plasma can reignite the plasma after the plasma is extinguished. - View Dependent Claims (2, 3, 4, 5)
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Specification