Differing boost voltages applied to two or more anodeless electrodes for plasma processing
First Claim
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1. A pulsed DC power supply system providing pulsed DC power to a plurality of anodeless electrodes sustaining a plasma in a plasma processing chamber, the pulsed DC power supply system comprising:
- a first DC power supply supplying a first DC power to a first and a second rail having a first rail voltage therebetween;
a first switching circuit receiving the first DC power via the first and second rails and converting the first DC power to a first pulsed DC voltage configured for delivery to at least a first anodeless electrode of the plasma processing chamber;
a first voltage-boosting circuit coupled between the first and second rails, the first voltage-boosting circuit including a first voltage multiplier and a first voltage multiplier modifier, the first voltage multiplier configured to draw current from the first DC power supply when an impedance of a plasma load increases thereby raising the first rail voltage by a first boost voltage V2, the first boost voltage V2 being selectable by the first voltage multiplier modifier;
a second DC power supply supplying a second DC power to a third and fourth rail having a second rail voltage therebetween;
a second switching circuit receiving the second DC power via the third and fourth rails and converting the second DC power to a second pulsed DC voltage configured for delivery to at least a second anodeless electrode of the plasma processing chamber; and
a second voltage-boosting circuit coupled between the first and second rails, the second voltage-boosting circuit including a second voltage multiplier and a second voltage multiplier modifier, the second voltage multiplier configured to draw current from the second DC power supply when the impedance of the plasma load increases thereby raising the second rail voltage by a second boost voltage V2′
, the second boost voltage V2′
being selectable by the second voltage multiplier modifier.
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Abstract
This disclosure describes a non-dissipative snubber circuit configured to boost a voltage applied to a load after the load'"'"'s impedance rises rapidly. The voltage boost can thereby cause more rapid current ramping after a decrease in power delivery to the load which results from the load impedance rise. In particular, the snubber can comprise a combination of a unidirectional switch, a voltage multiplier, and a current limiter. In some cases, these components can be a diode, voltage doubler, and an inductor, respectively.
31 Citations
19 Claims
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1. A pulsed DC power supply system providing pulsed DC power to a plurality of anodeless electrodes sustaining a plasma in a plasma processing chamber, the pulsed DC power supply system comprising:
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a first DC power supply supplying a first DC power to a first and a second rail having a first rail voltage therebetween; a first switching circuit receiving the first DC power via the first and second rails and converting the first DC power to a first pulsed DC voltage configured for delivery to at least a first anodeless electrode of the plasma processing chamber; a first voltage-boosting circuit coupled between the first and second rails, the first voltage-boosting circuit including a first voltage multiplier and a first voltage multiplier modifier, the first voltage multiplier configured to draw current from the first DC power supply when an impedance of a plasma load increases thereby raising the first rail voltage by a first boost voltage V2, the first boost voltage V2 being selectable by the first voltage multiplier modifier; a second DC power supply supplying a second DC power to a third and fourth rail having a second rail voltage therebetween; a second switching circuit receiving the second DC power via the third and fourth rails and converting the second DC power to a second pulsed DC voltage configured for delivery to at least a second anodeless electrode of the plasma processing chamber; and a second voltage-boosting circuit coupled between the first and second rails, the second voltage-boosting circuit including a second voltage multiplier and a second voltage multiplier modifier, the second voltage multiplier configured to draw current from the second DC power supply when the impedance of the plasma load increases thereby raising the second rail voltage by a second boost voltage V2′
, the second boost voltage V2′
being selectable by the second voltage multiplier modifier. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A pulsed DC power supply system configured to provide pulsed DC power to a plurality of anodeless electrodes of a plasma processing chamber, the pulsed DC power supply comprising:
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a first pulsed DC power supply system providing a DC current via a first and second rail; a first voltage-boosting circuit coupled between the first and second rail and periodically boosting a voltage of the rail by a first selectable boost voltage; a first switching circuit receiving the DC current via the first and second rail and generating a first pulsed DC voltage that is periodically boosted above a process voltage by the first selectable boost voltage; and first and second outputs configured to provide the first pulsed DC voltage to first and second anodeless electrodes, the first selectable boost voltage being different than a second selectable boost voltage configured to be provided to third and fourth anodeless electrodes. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method comprising:
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delivering a first bipolar pulsed DC voltage to a first anodeless electrode in a plasma processing chamber; delivering a second pulsed DC voltage to a second anodeless electrode in the plasma processing chamber, the first pulsed DC voltage having a boosted voltage V1+V2 magnitude for a first portion of each pulse of the first pulsed DC voltage, the second pulsed DC voltage having a boosted voltage V1+V2′
magnitude for a first portion of each pulse of the second pulsed DC voltage,each DC pulse in the first and second pulsed DC voltages having an opposite polarity to a previous pulse. - View Dependent Claims (16, 17, 18)
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19. A pulsed DC power supply system comprising:
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two or more pulsed DC power supply systems each configured to provide pulsed DC voltage to a different anodeless electrode within a plasma processing chamber, each pulsed DC voltage having a selectable boost voltage during a first portion of each pulse, and the selectable boost voltage being different for at least two of the pulsed DC power supply systems.
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Specification