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US 6,747,729 B2Granted
Lithographic projection apparatus, device manufacturing method, device manufactured thereby and gas composition
AssigneeASML Netherlands B.V.
InventorsWouter Onno Pril, Philip Dennis Henshaw, Engelbertus Antonius Fransiscus Van De Pasch, Marcel Hendrikus Maria Beems
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Abstract
A lithographic projection apparatus which uses one, and optionally also two or more color interferometric devices to accurately determine the position of a movable table within the apparatus. The apparatus comprises a purge gas source to supply purge gas to a space accommodating at least a part of said movable table, the purge gas being selected such that leakage of the purge gas into the area of operation of the interferometric devices does not cause significant error in the interferometric measurements.
Claims31
A lithographic projection apparatus comprising:
- a radiation system to provide a projection beam of radiation;
- patterning structure to pattern the projection beam according to a desired pattern;
- a substrate table to hold a substrate;
- a projection system to image the patterned beam onto a target portion of the substrate,
- a displacement measuring interferometer having an operating wavelength λ1 for measuring at least one of the position of said substrate table and the position of a table which is a part of said patterning structure;
- a purge gas source to supply purge gas to a space, to displace therefrom ambient air, said space accommodating at least one of at least a part of said substrate table and at least a part of said table which is a part of said patterning structure, wherein said purge gas is substantially non-absorbent of said projection beam of radiation and has a refractive index at a wavelength λ1 which is substantially the same as that of air when measured at equal wavelength, temperature and pressure.
3 more elements
A lithographic projection apparatus comprising:
- a radiation system to provide a projection beam of radiation;
- patterning structure to pattern the projection beam according to a desired pattern;
- a substrate table to hold a substrate;
- a projection system to image the patterned beam onto a target portion of the substrate;
- a displacement measuring interferometer having an operating wavelength λ1 to measure at least one of a position of said substrate table and a position of a table which is a part of said patterning structure;
- a second harmonic interferometer having operating wavelengths λ2 and λ3 to adjust measurements of the displacement measuring interferometer to substantially eliminate the effects of variation in pressure and temperature;
- a purge gas source to supply purge gas to a space, to displace therefrom ambient air, said space accommodating at least one of at least a part of said substrate table and at least a part of said table which is a part of said patterning structure, wherein said purge gas is substantially non-absorbent of said projection beam of radiation and comprises at least two components, each component having refractivities at the wavelengths λ1, λ2 and λ3 such that the following equation is substantially fulfilled:
- α m1 ( α m3 - α m2 ) = K a ( 4 )
- wherein αm1 is the refractivity of the purge gas at a wavelength λ1, αm2 is the refractivity of the purge gas at a wavelength λ2, αm3 is the refractivity of the purge gas at a wavelength λ3 and K a = α a1 ( α a3 - α a2 ) ( 5 )
- wherein αa1 is the refractivity of air at a wavelength λ1, αa2 is the refractivity of air at a wavelength λ2 and αa3 is the refractivity of air at a wavelength λ3.
7 more elements
A lithographic projection apparatus comprising:
- a radiation system to provide a projection beam of radiation;
- patterning structure to pattern the projection beam according to a desired pattern;
- a substrate table to hold a substrate;
- a projection system to image the patterned beam onto a target portion of the substrate;
- a purge gas source to supply purge gas to a space, to displace therefrom ambient air, said space accommodating at least one of at least a part of said substrate table and at least a part of said table which is a part of said patterning structure, wherein said purge gas is substantially non-absorbent of said projection beam of radiation;
- an displacement measuring interferometer having an operating wavelength λ1 for measuring at least one of the position of said substrate table and the position of said table which is a part of said patterning structure;
- and
- a second harmonic interferometer having operating wavelengths λ2 and λ3 to adjust measurements of the displacement measuring interferometer (DI) according to the following equation:
- L=(DI)−K(SHI) (9)
- wherein L is the adjusted displacement measuring interferometer measurement, SHI is the measurement of the second harmonic interferometer and K is a coefficient, the value of which is optimized such that effects of variation in pressure, temperature and purge gas composition are partially eliminated from the adjusted measurement L.
7 more elements
A device manufacturing method comprising:
- projecting a patterned beam of radiation onto a target area of a layer of radiation-sensitive material on a substrate;
- determining the position of a table using a displacement measuring interferometer having an operating wavelength λ1, said table comprising at least one of a substrate holder and a patterning structure;
- providing purge gas to a space accommodating at least a part of said table to displace therefrom ambient air, wherein said purge gas is substantially non-absorbent of said patterned beam of radiation and has a refractive index at a wavelength λ1 which is substantially the same as that of air when measured at the same wavelength, temperature and pressure.
A device manufacturing method comprising:
- projecting the patterned beam of radiation onto a target area of the layer of radiation-sensitive material,
- determining a position of a table using a displacement measuring interferometer having an operating wavelength λ1, said table comprising at least one of a substrate holder and a patterning structure;
- adjusting a measurement of said displacement measuring interferometer to substantially eliminate effects of variation in pressure and temperature using a second harmonic interferometer having operating wavelengths λ2 and λ3;
- providing purge gas to a space accommodating at least a part of said table to displace therefrom ambient air, wherein said purge gas is substantially non-absorbent of said patterned beam of radiation and comprises at least two components, each component having refractivities at the wavelengths λ1, λ2 and λ3 such that the following equation is substantially fulfilled:
- α m1 ( α m3 - α m2 ) = K a ( 4 )
- wherein αm1 is a refractivity of the purge gas at a wavelength λ1, αm2 is a refractivity of the purge gas at a wavelength λ2, αm3 is a refractivity of the purge gas at a wavelength λ3 and K a = α a1 ( α a3 - α a2 ) ( 5 )
- wherein αa1 is a refractivity index of air at a wavelength λ1, αa2 is a refractivity of air at a wavelength λ2 and αa3 is a refractivity of air at a wavelength λ3.
4 more elements
A device manufacturing method comprising:
- projecting a patterned beam of radiation onto a target area of a layer of radiation-sensitive material on a substrate,
- providing purge gas to a space accommodating at least a part of a table to displace therefrom ambient air, said table comprising at least one of a substrate holder and a patterning structure, wherein said purge gas is substantially non-absorbent of said projection beam of radiation;
- determining a position of said table using a displacement measuring interferometer having an operating wavelength λ1;
- and
- adjusting the measurement of said displacement measuring interferometer (DI) using a second harmonic interferometer having operating wavelengths λ2 and λ3 according to the following equation:
- L=(DI)−K(SHI) (9)
- wherein L is an adjusted displacement measuring interferometer measurement, SHI is a measurement of the second harmonic interferometer and K is a coefficient, a value of which is optimized such that the effects of variation in pressure, temperature and purge gas composition are partially eliminated from the adjusted value L.
4 more elements
Dependencies are inferred from the claim text.