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:
Jul. 22, 1997
Filed:
Jul. 25, 1995
Scott Gehlke, Berkeley, CA (US);
Ion Systems, Inc., Berkeley, CA (US);
Abstract
The present invention relates to ion emitter tip metals and alloys for ionizing the molecules of a gas which concurrently produces small diameter and very low numbers of unwanted particles. Specifically, the invention discloses ion emitter tip materials which, when subjected to normal operating electrical conditions of between about 0.1 and 100 microamperes per emitter tip, produces about 1 particle or less having a diameter of about 0.5 microns or less per cubic foot. Useful ion emitter tip materials include zirconium, titanium, molybdenum, tantalum, rhenium or alloys of these metals. In a specific embodiment, the metal alloys comprise zirconium and rhenium, titanium and rhenium, molybdenum and rhenium, or tantalum and rhenium. Silicon coated metal emitter tips, particularly titanium-silicon coated are disclosed. The emitter tip materials are useful to obtain Class 1 clean room standards in static air or flowing air environments used, for example, in semiconductor manufacture. A preferred ion emitter tip is of silicon of 99.99% plus purity, optionally containing a dopant of phosphorus, boron or antimony. The emitter tip is has a cone/cylinder shape.