Lithographic apparatus and device manufacturing method
A lithographic apparatus, includes a support structure configured to hold a patterning device, the patterning device configured to impart a beam of radiation with a pattern in its cross-section; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; a liquid supply system configured to provide liquid to a space between the projection system and the substrate table; a sensor configured to measure an exposure parameter using a measuring beam projected through the liquid; and a correction system configured to determine an offset based on a change of a physical property impacting a measurement made using the measuring beam to at least partly correct the measured exposure parameter.
1. A method for correcting a constant parameter associated with a lithographic apparatus, the method comprising:
measuring a value of a physical property of the lithographic apparatus; and
determining a rate of change of said constant relative to the measured value or a rate of change of an exposure parameter relative to the measured value to correct a wavelength dependency of said constant parameter.
2. The method of claim 1 , wherein said constant parameter is a parameter associated with a projection system of the lithographic apparatus.
3. The method of claim 2 , wherein said constant parameter represents a positioning of one or more optical elements in the projection system.
4. The method of claim 1 , wherein said constant parameter is a parameter associated with an alignment system of the lithographic apparatus.
5. The method of claim 4 , wherein said constant parameter represents an alignment mark configuration or an alignment mark location of the alignment system.
6. The method of claim 1 , wherein the physical property is a temperature or a pressure.
7. The method of claim 1 , wherein the exposure parameter comprises a focus of a patterned beam, a height of a substrate, or both.
8. The method of claim 1 , wherein said lithographic apparatus is an immersion lithographic apparatus.
9. The method of claim 8 , wherein said exposure parameter is measured using a measuring beam projected through liquid between a projection system and a table of the lithographic apparatus.
10. A computer program product for correcting a constant parameter associated with a lithographic apparatus, comprising:
software code configured to measure a value of a physical property of the lithographic apparatus; and
software code configured to determine a rate of change of said constant relative to the measured value or a rate of change of an exposure parameter relative to the measured value to correct a wavelength dependency of said constant parameter.
11. The computer program product of claim 10 , wherein said constant parameter is a parameter associated with a projection system of the lithographic apparatus.
12. The computer program product of claim 11 , wherein said constant parameter represents a positioning of one or more optical elements in the projection system.
13. The computer program product of claim 10 , wherein said constant parameter is a parameter associated with an alignment system of the lithographic apparatus.
14. The computer program product of claim 13 , wherein said constant parameter represents an alignment mark configuration or an alignment mark location of the alignment system.
15. The computer program product of claim 10 , wherein the physical property is a temperature or a pressure.
16. The computer program product of claim 10 , wherein the exposure parameter comprises a focus of a patterned beam, a height of a substrate, or both.