Lithographic apparatus and device manufacturing method
First Claim
1. A lithographic projection apparatus comprising:
- a substrate table configured to hold a substrate;
a projection system arranged to project a patterned radiation beam onto a target portion of the substrate;
a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid;
a liquid confinement member, with respect to which the substrate table is movable, extending along at least part of a boundary of the space, the liquid confinement member having an opening configured to form a fluid seal between the liquid confinement member and a surface of the substrate or substrate table, wherein the opening is configured to remove liquid from the space; and
a bubble reduction device configured to reduce a size of bubbles in the liquid, a concentration of bubbles or gas in the liquid, or both, the bubble reduction device comprising a degassing device configured to degas the liquid.
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Accused Products
Abstract
A lithographic apparatus and device manufacturing method makes use of a liquid confined in a reservoir between the projection system 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/or removed so that they do not interfere with exposure and lead to printing defects on the substrate. Detection may be carried out by measuring the frequency dependence of ultrasonic attenuation in the liquid and bubble removal may 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/or phase shifting ultrasonic standing-wave node patterns.
200 Citations
21 Claims
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1. A lithographic projection apparatus comprising:
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a substrate table configured to hold a substrate; a projection system arranged to project a patterned radiation beam onto a target portion of the substrate; a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid; a liquid confinement member, with respect to which the substrate table is movable, extending along at least part of a boundary of the space, the liquid confinement member having an opening configured to form a fluid seal between the liquid confinement member and a surface of the substrate or substrate table, wherein the opening is configured to remove liquid from the space; and a bubble reduction device configured to reduce a size of bubbles in the liquid, a concentration of bubbles or gas in the liquid, or both, the bubble reduction device comprising a degassing device configured to degas the liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A lithographic apparatus comprising:
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a projection system configured to image a pattern on a substrate; a table movable with respect to the projection system; a liquid supply system configured to supply liquid to a reservoir between the projection system and the table; a liquid confinement member extending along at least part of a boundary of the reservoir, the liquid confinement member configured to substantially contain the liquid in the reservoir to a region on the substrate or substrate table having an area smaller than the area of the substrate, the region surrounded by a gaseous atmosphere; and a degassing device to degas the liquid, wherein the degassing device is located upstream of the space and configured to degas the liquid prior to supply to the space. - View Dependent Claims (18, 19, 20)
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21. A device manufacturing method, the method comprising:
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at least partly filling a space between a projection system of a lithographic apparatus and a movable table with a liquid; confining the liquid to the space using a liquid confinement member, with respect to which the table is movable, extending along at least part of a boundary of the space; forming a fluid seal between the liquid confinement member and a surface of the substrate or table; projecting a radiation image through the liquid in the space onto a target portion of a substrate; and degassing the liquid using a degasser, wherein the degasser is located upstream of the space and the degassing the liquid is performed prior to supply of the liquid to the space.
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Specification