Adjustable non-dissipative voltage boosting snubber network for achieving large boost voltages

Patent metadata

Field	Value
Publication number	US-9520269-B2
Application number	US-201514945331-A
Country	US
Kind code	B2
Filing date	Nov 18, 2015
Priority date	Nov 1, 2012
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

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.

First claim

What is claimed is:

1. 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:
a pulsed DC power supply system coupled to and providing a DC current via a first and second rail;
a voltage-boosting circuit coupled between the first and second rail and comprising:
a first diode coupled between the first rail and a first electrical node, an anode of the first diode being at a voltage of the first rail;
a voltage multiplier coupled between the second rail and the first electrical node, the voltage multiplier having an output;
a first inductive element coupled between the first rail and a second electrical node;
a first switch coupled between the first and second electrical nodes and selectively discharging a portion of a voltage stored in the voltage multiplier through the first inductive element to the first rail;
a second diode coupled between the first rail and a third electrical node, an anode of the second diode being at a voltage of the third electrical node; and
a second inductive element being coupled between the output of the voltage multiplier and the third electrical node;

a switching circuit coupled to the first and second rails and receiving the DC current via the first and second rails and generating a pulsed DC voltage, the switching circuit having first and second outputs configured to provide the first pulsed DC voltage to at least first and second anodeless electrodes of the plasma processing chamber.

2. The pulsed DC power supply system of claim 1 , wherein the voltage multiplier comprises two capacitive elements arranged to charge in series and discharge in parallel.

3. The pulsed DC power supply system of claim 2 , wherein a first of the two capacitive elements is arranged so as to discharge through the first switch and the first inductor and the second of the two capacitive elements is arranged so as to discharge through the output of the voltage multiplier, the second inductive element, and the second diode.

4. The pulsed DC power supply system of claim 3 , wherein the first switch is selected from the group consisting of: insulated-gate bipolar transistors (IGBTs), bipolar junction transistors, and field effect transistors.

5. The pulsed DC power supply system of claim 2 , wherein the voltage multiplier comprises the first and second capacitive elements arranged in parallel and at least a third and fourth diode, the third diode having an anode coupled to the first capacitive element and having a cathode coupled to the second capacitive element, the cathode of the third diode being at a same potential as the output of the voltage multiplier, wherein the fourth diode has a cathode at a same potential as the anode of the third diode and the fourth diode having an anode at the same potential as the second rail.

6. The pulsed DC power supply system of claim 1 , wherein the voltage multiplier increases a rail voltage V AB between the first and second rails by at least a factor of two when the plasma impedance load substantially decreases.

7. The pulsed DC power supply system of claim 1 , further comprising a second switch selectively coupling the second rail and the third electrical node.

8. The pulsed DC power supply system of claim 1 , wherein the first rail is positive and the second rail is negative.

9. The pulsed DC power supply system of claim 1 , wherein the switching circuit further comprises two or more half or full bridge H-bridge circuits coupled in parallel between the first and second rails and the first and second outputs.

10. The pulsed DC power supply system of claim 9 , wherein outputs of a first of the two or more half or full bridge H-bridge circuits are parallel to outputs of a second of the two or more half or full bridge H-bridge circuits.

11. The pulsed DC power supply system of claim 3 , wherein a controller closes the first switch when the controller determines that a voltage between the first and second rails has reached or exceeded a first threshold, V max , and opens the switch when the controller determines that the voltage between the first and second rails has reached or fallen below a second threshold, V min .

12. The pulsed DC power supply system of claim 11 , further comprising a second switch selectively coupling the second rail and the third electrical node, and further comprising a voltage sensor coupled across the second of the two capacitive elements, wherein the second switch has a duty cycle that is a function of a voltage across the second switch as measured by the voltage sensor.

13. A method of operating a voltage-boosting circuit arranged between a first and second rail carrying DC current to a switching circuit that converts DC current on the first and second rails to a pulsed DC voltage and provides the pulsed DC voltage across a plasma load of a plasma processing chamber, the method comprising:
providing a rail voltage V AB between the first and second rails equal to a process voltage V 1 ;
absorbing some of the DC current in a capacitive element when an impedance of the plasma load increases sufficiently to forward bias a diode coupled between the first rail and a first electrical node, the capacitive element being coupled between the second rail and the first electrical node;
raising the rail voltage V AB to greater than twice the process voltage V 1 as a result of the absorbing;
closing a switch coupled between the first electrical node and a second electrical node after the raising;
lowering the rail voltage V AB to the process voltage V 1 as a result of the closing; and
discharging, during the lowering, at least a portion of charge stored in the capacitive element through the switch and an inductive element, the inductive element being coupled between the first rail and the second electrical node.

14. The method of claim 13 , further comprising charging the capacitive element via the diode and discharging the capacitive element via the switch and the inductive element.

15. The method of claim 14 , further comprising opening the switch after the diode becomes reverse biased but before a switching of the switching circuit.

16. A method of operating a voltage-boosting circuit, comprising:
the voltage-boosting circuit being arranged between a first and second rail carrying DC current to a switching circuit that converts DC current on the first and second rails to a pulsed DC voltage and providing the pulsed DC voltage across a plasma load of a plasma processing chamber, and wherein the method comprising:
absorbing in a voltage multiplier some of the DC current when an impedance of the plasma load substantially increases;
discharging to the switching circuit at least some energy stored in the voltage multiplier from the absorbed DC current, and thereby boosting a voltage of the DC current;
monitoring a voltage across a capacitive element of the voltage multiplier that absorbs some of the DC current;
closing the switch when the voltage exceeds a maximum voltage threshold;
reducing the voltage across the capacitive element as a result of the closing until the voltage falls below a minimum voltage threshold; and then
opening the switch when the voltage falls below the minimum voltage threshold; and
increasing the voltage across the capacitive element as a result of the opening.

17. The method of claim 16 , wherein discharge of the voltage-boosting circuit boosts a rail voltage V AB between the first and second rail by a boost voltage V 2 , wherein the boost voltage V 2 i

Assignees

• Advanced Energy Ind Inc

Inventors

• Finley Kenneth W
• Walde Hendrik

Classifications

• H01J37/32027 Primary

  DC powered · CPC title

• H05H1/46

  using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) · CPC title

• H01J37/32064 Primary

  Circuits specially adapted for controlling the arc discharge (for plasma torches H01H1/36) · CPC title

• H01J37/32055

  Arc discharge · CPC title

• H01J37/34

  operating with cathodic sputtering (H01J37/36 takes precedence {; methods of cathodic sputtering C23C14/34}) · CPC title