A.C. plasma processing system
AssigneeSierra Applied Sciences, Inc.
InventorsBarry W. Manley, Keith H. Billings
Life of this patent
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Abstract
An AC plasma processing system according to the present invention may include a transformer for placing an alternating current on a first electrode and a second electrode contained within a process chamber. The secondary winding of the transformer is connected across the first and second electrodes. The primary winding of the transformer is connected to an external power supply. A switching device connected to the primary winding of the transformer periodically short circuits the primary winding to induce a secondary voltage in the secondary winding that is less than the arcing voltage associated with the process chamber.
Claims20
A circuit for placing an alternating current on a first electrode and a second electrode positioned within a process chamber, the process chamber having associated with it an arcing voltage above which an arc condition exists, comprising:
- a transformer having a primary winding and a secondary winding, the primary winding having a first end lead and a second end lead both of which are connected to an external power supply, the secondary winding being connected across the first and second electrodes;
- switching means connected to the first and second end leads of the primary winding for periodically short circuiting the primary winding, wherein the short circuited primary winding induces a secondary voltage in the secondary winding that is less than the arcing voltage.
A circuit for placing an alternating voltage potential across a first electrode and a second electrode, positioned within a plasma processing chamber comprising:
- a transformer having a primary winding and a secondary winding, the primary winding having a first end lead, a center tap lead, and a second end lead, the center tap lead being connected to a first terminal of an external power supply, the secondary winding being connected across the first and second electrodes;
- a first switching device connected between the first end lead of the primary winding and a second terminal of the external power supply, said first switching device being switchable from a conductive state to a non-conductive state to electrically connect and disconnect the first end lead of the primary winding and the second terminal of the external power supply;
- a second switching device connected between the second end lead of the primary winding and the second terminal of the external power supply, said second switching device being switchable from a conductive state to a non-conductive state to electrically connect and disconnect the second end lead of the primary winding and the second terminal of the external power supply;
- a switching device control system connected to said first and second switching devices, said switching device control system being operable to actuate said first and second switching devices independently of the other to place the alternating voltage potential across the first and second electrodes.
A plasma processing system, comprising:
- a vacuum chamber having a first electrode and a second electrode, said vacuum chamber being adapted to receive a process gas and maintain said process gas within a predetermined pressure;
- a transformer having a primary winding and a secondary winding, the primary winding having a first end lead, a center tap lead, and a second end lead, the center tap lead being connected to a first terminal of an external power supply, the secondary winding being connected across the first and second electrodes;
- a first switching device connected between the first end lead of the primary winding and a second terminal of the external power supply, said first switching device being switchable from a conductive state to a non-conductive state to electrically connect and disconnect the first end lead of the primary winding and the second terminal of the external power supply;
- a second switching device connected between the second end lead of the primary winding and the second terminal of the external power supply, said second switching device being switchable from a conductive state to a non-conductive state to electrically connect and disconnect the second end lead of the primary winding and the second terminal of the external power supply;
- a switching device control system connected to said first and second switching devices, said switching device control system being operable to actuate said first and second switching devices independently of the other to place the alternating voltage potential across the first and second electrodes.
Dependencies are inferred from the claim text.