Charge removal from electrodes in unipolar sputtering system
AssigneeAdvanced Energy Industries, Inc.
InventorKenneth W. Finley
Life of this patent
Estimating the term…
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.
Claims21
A pulsed DC power supply system configured to provide pulsed DC voltage between an anode and a cathode of a plasma processing chamber, the pulsed DC voltage including a first power delivery period of positive voltage separated from a second power delivery period by a charge removal period comprising a charge removal voltage having a negative polarity for removing charge from the cathode, the pulsed DC power supply system comprising:
- a DC power supply coupled to and providing power to a first and second rail;
- a switching circuit coupled to the first and second rails and switched so as to convert the power on the first and second rails to the pulsed DC voltage, where positive voltage is referenced from the anode to the cathode;
- a voltage-boosting circuit coupled between the first and second rails and comprising:
- a first unidirectional switch coupled between the first rail and a first electrical node and only allowing current to pass from the first rail to the first electrical node;
- a voltage multiplier coupled between the second rail and the first electrical node and including an output that provides access to a charge removal voltage within the voltage multiplier;
- a switch coupled between the first electrical node and a second electrical node;
- a first current limiter coupled between the second electrical node and the first rail;
- and
- a charge removal bias circuit coupled to the output of the voltage multiplier and providing the charge removal voltage to the switching circuit.
A pulsed DC power supply system comprising:
- a DC power supply coupled to and providing power to a first and second rail;
- a switching circuit coupled to the first and second rails and switched so as to convert the power on the first and second rails to a pulsed DC voltage;
- a voltage-boosting circuit coupled between the first and second rails and comprising:
- a first unidirectional switch coupled between the first rail and a first electrical node and only allowing current to pass from the first rail to the first electrical node;
- a voltage multiplier coupled between the second rail and the first electrical node and including an output that provides access to a negative charge removal voltage within the voltage multiplier;
- a switch coupled between the first electrical node and a second electrical node;
- a first current limiter coupled between the second electrical node and the first rail;
- and
- a charge removal bias circuit coupled to at least the second rail and the switching circuit and providing the negative charge removal voltage to the switching circuit.
Dependencies are inferred from the claim text.