The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 17, 2004
Filed:
Apr. 04, 2001
Joseph C. Olson, Beverly, MA (US);
Daniel Distaso, Merrimac, MA (US);
Anthony Renau, West Newbury, MA (US);
Varian Semiconductor Equipment Associates, Inc., Gloucester, MA (US);
Abstract
An indirectly heated cathode ion source includes an extraction current sensor for sensing ion current extracted from the arc chamber and an ion source controller for controlling the filament power supply, the bias power supply and/or the arc power supply. The ion source controller may compare the sensed extraction current with a reference extraction current and determine an error value based on the difference between the sensed extraction current and the reference extraction current. The power supplies of the indirectly heated cathode ion source are controlled to minimize the error value, thus maintaining a substantially constant extraction current. The ion source controller utilizes a control algorithm, for example a closed feedback loop, to control the power supplies in response to the error value. In a first control algorithm, the bias current I supplied by the bias power supply is varied so as to control the extraction current I . Further according to the first control algorithm, the filament current I and the arc voltage V are maintained constant. According to a second control algorithm, the filament current I is varied so as to control the extraction current I . Further according to the second control algorithm, the bias current I and the arc voltage V are maintained constant.