Lithographic apparatus and device manufacturing method
First Claim
1. A lithographic projection apparatus comprising:
- a radiation system for providing a projection beam of radiation;
a support structure for supporting patterning means, the patterning means serving to pattern the projection beam according to a desired pattern;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate;
a liquid supply system for at least partly filling a space between the final element of said projection system and said substrate with liquid, wherein said liquid supply system comprises bubble reduction means.
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Accused Products
Abstract
A lithographic apparatus and device manufacturing method makes use of a high refractive index liquid confined in a reservoir 13 at least partly filling the imaging field between the final element of the projection lens and the substrate. Bubbles forming in the liquid from dissolved atmospheric gases or from out-gassing from apparatus elements exposed to the liquid are detected and removed so that they do not interfere with exposure and lead to printing defects on the substrate. Detection can be carried out by measuring the frequency dependence of ultrasonic attenuation in the liquid and bubble removal can be implemented by degassing and pressurizing the liquid, isolating the liquid from the atmosphere, using liquids of low surface tension, providing a continuous flow of liquid through the imaging field, and phase shifting ultrasonic standing-wave node patterns.
247 Citations
24 Claims
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1. A lithographic projection apparatus comprising:
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a radiation system for providing a projection beam of radiation;
a support structure for supporting patterning means, the patterning means serving to pattern the projection beam according to a desired pattern;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate;
a liquid supply system for at least partly filling a space between the final element of said projection system and said substrate with liquid, wherein said liquid supply system comprises bubble reduction means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A lithographic projection apparatus comprising:
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a radiation system for providing a projection beam of radiation;
a support structure for supporting patterning means, the patterning means serving to pattern the projection beam according to a desired pattern;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate;
a liquid supply system for at least partly filling a space between the final element of said projection system and said substrate with liquid; and
a detection system for detecting impurities in said liquid, including a light source, a light detector and a light comparator, said light source and said light detector being arranged so that light emitted by said source propagates between said source and said detector through a portion of said liquid, said comparator being arranged to detect changes in the proportion of said emitted light that arrives at said detector after propagation through a portion of said liquid. - View Dependent Claims (22)
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23. A device manufacturing method comprising:
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providing a substrate that is at least partially covered by a layer of radiation-sensitive material;
providing a projection beam of radiation using a radiation system;
using patterning means to endow the projection beam with a pattern in its cross-section;
projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material;
providing a liquid supply system for at least partly filling a space between the final element of said projection system and said substrate with liquid; and
reducing bubbles in said liquid supply system.
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24. A lithographic projection apparatus comprising:
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a radiation system for providing a projection beam of radiation;
a support structure for supporting patterning means, the patterning means serving to pattern the projection beam according to a desired pattern;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate;
a liquid supply system for at least partly filling a space between the final element of said projection system and said substrate with liquid; and
a liquid quality monitor capable of switching the operational state of the projection apparatus between an active state and a suspended state, said active state being selected when the liquid quality is determined to be above a predefined threshold and said suspended state being selected when the liquid quality is determined to be below a predefined threshold state.
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Specification