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US 6,190,512 B1Granted
Soft plasma ignition in plasma processing chambers
AssigneeTokyo Electron Arizona Inc.
InventorAlexander D. Lantsman
Life of this patent
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Abstract
The specification discloses a power supply circuit which reduces oscillations generated upon ignition of a plasma within a processing chamber. A secondary power supply pre-ignites the plasma by driving the cathode to a process initiation voltage. Thereafter, a primary power supply electrically drives the cathode to generate plasma current and deposition on a wafer.
Claims7
A method of plasma processing a workpiece in a vacuum chamber having a cathode, comprising
- evacuating said chamber,
- elevating said cathode to a process initiation voltage relative to said chamber while said chamber is evacuated, said process initiation voltage being insufficient to fully ignite or maintain a plasma within said chamber,
- flowing a gas into said chamber while maintaining said cathode at said process initiation voltage, and thereafter
- applying electrical power to said cathode to elevate said cathode to a processing voltage greater than said process initiation voltage to fully ignite a plasma from said gas within said chamber and cause electrical current to flow through said plasma,
- maintaining said cathode at said processing voltage to maintain ignition of a plasma in said chamber while processing said workpiece within said chamber.
2 more elements
Dependencies are inferred from the claim text.