Charge removal from electrodes in unipolar sputtering system
AssigneeAdvanced Energy Industries, Inc.
InventorKenneth W. Finley
Life of this patent
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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.
Claims17
A pulsed DC power supply system comprising:
- a first and second rail configured to receive power from a DC power supply and provide a rail voltage;
- a charge removal bias circuit coupled to a switching circuit and coupled to the second rail or a voltage-boosting circuit coupled between the first and second rails, the charge removal bias circuit having at least one output coupled to the switching circuit and configured to provide a charge removal voltage;
- the switching circuit coupled to the first and second rails, and having two outputs for coupling to a plasma load, the switching circuit arranged between the charge removal bias circuit and the two outputs, the switching configured to provide, at the two outputs, a voltage that is switched between at least a process voltage derived from the rail voltage and the charge removal voltage, wherein the process voltage and the charge removal voltage have opposite polarity.
A pulsed DC power supply system comprising:
- a first and second rail configured to receive power from a DC power supply, and having a rail voltage between the first and second rails;
- a charge removal bias circuit coupled to at least the second rail or to a voltage-boosting circuit coupled between the first and second rails, the charge removal bias circuit configured to provide a charge removal voltage;
- and
- a switching circuit coupled to the first and second rails and to the charge removal bias circuit, configured to receive (1) the rail voltage from the first and second rails and (2) the charge removal voltage from the charge removal bias circuit, and configured to be switched so as to provide a pulsed DC voltage having interlaced positive and negative pulses, an amplitude of the positive pulses equal to the rail voltage, and an amplitude of the negative pulses equal to the charge removal voltage.
A pulsed DC power supply comprising:
- a voltage-boosting circuit arranged between a first and second rail configured to receive power from a DC power supply, the voltage-boosting circuit configured to adjust a rail voltage measured from the first rail to the second rail;
- a switching circuit having three inputs, a first and second of these inputs coupled to the first and second rails and having two outputs configured for coupling to a plasma load, the switching circuit configured to provide pulses at the two outputs interlacing at least (1) the rail voltage having a first polarity at the two outputs and (2) a charge removal voltage having a second polarity at the two outputs;
- and
- a charge removal bias circuit configured to provide the charge removal voltage and having an output coupled to the third input of the switching circuit and one or more inputs coupled to:
- (1) the first and second rails;
- (2) the second rail;
- or (3) an output of the voltage-boosting circuit.
Dependencies are inferred from the claim text.