Lithographic projection apparatus, device manufacturing method and device manufactured thereby
First Claim
1. A lithographic projection apparatus comprising:
- a radiation system to supply a projection beam of radiation;
a support structure adapted to support patterning structure which can be used to pattern the projection beam according to a desired pattern;
a substrate table to hold a substrate;
a projection system to project the patterned beam onto a target portion of the substrate;
a gas supply, configured and arranged to supply a gaseous hydrocarbon to a space containing a mirror;
at least one sensor selected from the group comprising a reflectivity sensor to monitor a reflectivity of said mirror and a pressure sensor to monitor a background pressure in said space; and
a gas supply control to control said gas supply to control, responsive to a signal from said at least one sensor, a thickness of a layer of hydrocarbon formed on the mirror using the gaseous hydrocarbon.
3 Assignments
0 Petitions
Accused Products
Abstract
A lithographic projection apparatus comprising a radiation system for supplying a projection beam of electromagnetic radiation in the extreme ultraviolet (EUV) range, a support structure for supporting patterning structure, the patterning structure serving to pattern the projection beam according to a desired pattern, a substrate table for holding a substrate and a projection system for projecting the patterned beam onto a target portion of the substrate. A space within the apparatus, which space contains a mirror, is supplied with a hydrocarbon gas which forms a protective cap layer on the mirror surface. The partial pressure of the hydrocarbon gas in the space is controlled in response to variations in the background pressure in the space and/or in the reflectivity of the mirror, such that the thickness of the cap layer on the mirror remains within an acceptable range. The partial pressure of hydrocarbon may be increased in order to sputter away the cap layer and/or, if extra multilayers are provided on the mirror, the top layer(s) of the mirror, thus providing a clean mirror surface. The hydrocarbon used may be an alcohol, in which case the cap layer formed is self-terminating.
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Citations
24 Claims
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1. A lithographic projection apparatus comprising:
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a radiation system to supply a projection beam of radiation; a support structure adapted to support patterning structure which can be used to pattern the projection beam according to a desired pattern; a substrate table to hold a substrate; a projection system to project the patterned beam onto a target portion of the substrate; a gas supply, configured and arranged to supply a gaseous hydrocarbon to a space containing a mirror; at least one sensor selected from the group comprising a reflectivity sensor to monitor a reflectivity of said mirror and a pressure sensor to monitor a background pressure in said space; and a gas supply control to control said gas supply to control, responsive to a signal from said at least one sensor, a thickness of a layer of hydrocarbon formed on the mirror using the gaseous hydrocarbon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of manufacturing a device using a lithographic projection apparatus comprising:
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projecting a patterned beam of radiation onto a target portion of a layer of radiation-sensitive material on a substrate; supplying a gaseous hydrocarbon to a space within the lithographic projection apparatus containing a mirror; monitoring at least one of a reflectivity of said mirror and a background pressure in said space; and controlling an amount of gaseous hydrocarbon supplied to said space to control, in response to the monitoring, a thickness of a hydrocarbon layer formed on the mirror using the gaseous hydrocarbon. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of manufacturing a device using a lithographic projection apparatus comprising:
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projecting a patterned beam of radiation onto a target portion of a layer of radiation-sensitive material on a substrate; and supplying a gaseous alcohol to a space in a radiation system of the lithographic projection apparatus, which space contains a mirror, wherein the alcohol forms a cap layer on said mirror, wherein, during the projecting, particles impinge the cap layer from a source other than the cap layer and the mirror and cause particles of the cap layer to be dislodged from the cap layer by sputtering, and wherein the gaseous alcohol is supplied to said space at a pressure sufficient to achieve a thickness of said cap layer which does not increase substantially over time. - View Dependent Claims (19, 20)
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21. A lithographic projection apparatus comprising:
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a support structure adapted to support patterning structure which can be used to pattern a beam of radiation according to a desired pattern; a substrate table to hold a substrate; a projection system to project the patterned beam onto a target portion of the substrate; a gas supply configured to supply a gaseous hydrocarbon to a space containing a mirror; and a gas supply control configured to control supply of the gaseous hydrocarbon to the space to maintain a layer formed on the mirror using the gaseous hydrocarbon at a substantially constant thickness in response to, during supply of the projection beam, particles of the cap layer being dislodged from the cap layer by sputtering caused by particles impinging the cap layer from a source other than the cap layer and the mirror. - View Dependent Claims (22, 23, 24)
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Specification