Fluid pressure compensation for immersion lithography lens
First Claim
1. An apparatus, comprising:
- a wafer table that supports a wafer;
an optical assembly that projects an image onto the wafer supported by the wafer table, the optical assembly having a final optical element spaced from the wafer by a gap;
an immersion element that provides an immersion fluid into the gap between the final optical element and the wafer; and
a fluid compensation system that compensates for a first force applied to the final optical element of the optical assembly caused by pressure variations of the immersion fluid to minimize displacement of the final optical element, the fluid compensation system applying a second force to the final optical element, the second force having a direction opposite a direction of the first force.
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Accused Products
Abstract
An immersion lithography system that compensating for any displacement of the optical caused by the immersion fluid. The system includes an optical assembly (14) to project an image defined by the reticle (12) onto the wafer (20). The optical assembly includes a final optical element (16) spaced from the wafer by a gap (24). An immersion element (22) is provided to supply an immersion fluid into the gap and to recover any immersion fluid that escapes the gap. A fluid compensation system is provided for the force on the final optical element of the optical assembly caused by pressure variations of the immersion fluid. The resulting force created by the varying pressure may cause final optical element to become displaced. The fluid compensation system is configured to provide a substantially equal, but opposite force on the optical assembly, to prevent the displacement of the final optical element.
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Citations
27 Claims
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1. An apparatus, comprising:
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a wafer table that supports a wafer; an optical assembly that projects an image onto the wafer supported by the wafer table, the optical assembly having a final optical element spaced from the wafer by a gap; an immersion element that provides an immersion fluid into the gap between the final optical element and the wafer; and a fluid compensation system that compensates for a first force applied to the final optical element of the optical assembly caused by pressure variations of the immersion fluid to minimize displacement of the final optical element, the fluid compensation system applying a second force to the final optical element, the second force having a direction opposite a direction of the first force. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus, comprising:
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a wafer table that supports a wafer; an optical assembly that projects an image onto the wafer held by the wafer table, the optical assembly having a final optical element spaced from the wafer by a gap; an immersion element that provides an immersion fluid into the gap between the final optical element and the wafer, the immersion element having one or more gas nozzles that provide a flow of gas; a pressure sensor that measures the pressure of the immersion fluid in the gap; and a gas control system, coupled to the pressure sensor, and that controls a velocity of the flow of gas from the one or more gas nozzles based on the pressure measured by the pressure sensor. - View Dependent Claims (20, 21, 22, 23)
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24. An exposure method in which an optical assembly projects an image onto a wafer held by a wafer table, the optical assembly having a final optical element spaced from the wafer by a gap, the method comprising:
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providing an immersion fluid into the gap between the final optical element and the wafer using an immersion element, the immersion element having one or more gas nozzles that provide a flow of gas; measuring the pressure of the immersion fluid in the gap using a pressure sensor; and controlling a velocity of the flow of gas from the one or more gas nozzles based on the pressure measured by the pressure sensor using a gas control system coupled to the pressure sensor. - View Dependent Claims (25, 26, 27)
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Specification