Method of cleaning optical surfaces of an irradiation unit in a two-step process

US8076655B2 · kind B2 · utility

Assignee

• KONINKLIJKE PHILIPS ELECTRONICS NV · NL

Inventors

• Guenther Hans Derra · Aachen, DE
• Thomas Kruecken · Aachen, DE
• Christof Metzmacher · Verviers, BE
• Achim Weber · Altbach, DE
• Peter Zink · Aachen, DE

Key dates

• Filing date: Jun 7, 2006
• Grant date: Dec 13, 2011
• Expiry date: Jan 5, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70925
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

The present invention provides a method of cleaning optical surfaces in an irradiation unit in order to remove contaminations deposited on said optical surfaces. The method includes a cleaning step in which a first gas or gas mixture is brought into contact with said optical surfaces thereby forming a volatile compound with a first portion of said contaminations. In an operation pause of the irradiation unit prior to the cleaning step, a pretreatment step is performed, in which a second gas or gas mixture is brought into contact with said optical surfaces. Said second gas or gas mixture is selected to react with a second portion of said contaminations different from said first portion to form a reaction product, which is able to form a volatile compound with said first gas or gas mixture.