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AssigneeKoninklijke Philips Electronics N.V.
InventorsGuenther Hans Derra, Thomas Kruecken, Christof Metzmacher, Achim Weber, Peter Zink
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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.
Method of cleaning optical surfaces in an irradiation unit for EUV-radiation in order to remove contaminations deposited on said optical surfaces, the method including 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, wherein in an operation pause of the irradiation unit for EUV-radiation 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, wherein 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, wherein after the cleaning step residues still remaining on the optical surfaces are removed from said optical surfaces or converted into compounds less absorbing radiation of the irradiation unit by a treatment with a third gas or gas mixture.
Method of cleaning optical surfaces in an irradiation unit in order to remove contaminations deposited on said optical surfaces, the method including 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, wherein in an operation pause of the irradiation unit for EUV-radiation 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, wherein 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, wherein said first and/or second gas or gas mixture is delivered through a gas distribution unit (14) comprising several inlet and/or outlet openings (15) close to said optical surfaces and made of a material causing a low loss of radicals or coated inside with such a material and wherein said optical surfaces are brought into contact with said first and/or second gas or gas mixture in a time-dependent order by using one or several mechanical shutters (19) for opening or closing said inlet and/or outlet openings (15).
Dependencies are inferred from the claim text.