Projection unit for a level sensor, method of monitoring height of a substrate, and lithographic system comprising the projection unit
AssigneeASML Netherlands B.V.
InventorsAhmet Burak Cunbul, Ferry Zijp, Teunis Willem Tukker, Peter Fernand William Jozef Dendas, Abraham Franciscus Hubertus Van Gessel
Life of this patent
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Abstract
A projection unit for a level sensor, the projection unit including: a first light pipe having a first inlet configured to receive radiation from a source and a first outlet; and a second light pipe having a second inlet configured to receive the radiation from the first light pipe and a second outlet. The unit may include a lens device configured to receive radiation from the second outlet and to output radiation having a predetermined distribution of intensity and irradiance.
Claims20
A projection unit for a level sensor, the projection unit comprising:
- a first light pipe having a first inlet configured to receive radiation from a source and a first outlet;
- a second light pipe having a second inlet configured to receive the radiation from the first light pipe and a second outlet;
- a lens system configured to receive radiation from the second outlet and to output radiation having a predetermined distribution of intensity and irradiance;
- a grating arranged to be illuminated by the radiation exiting the lens system, the grating comprising an array of grating units, each grating unit comprising a number of slits having a predetermined size to filter the radiation;
- and
- an image multiplier device arranged to receive radiation exiting the grating, the radiation exiting the grating having an aspect ratio, and the image multiplier device configured to increase the aspect ratio.
A method of monitoring height of a substrate, the method comprising:
- receiving radiation from a radiation source into a first light pipe of a projection unit of a level sensor, wherein at least some of the radiation reflects off an interior of the first light pipe;
- receiving radiation exiting the first light pipe into a second light pipe of the projection unit of the level sensor, wherein at least some of the radiation reflects off an interior of the second light pipe;
- and
- providing the radiation from the second light pipe toward the substrate for monitoring of the height of the substrate.
A projection unit for a level sensor, the projection unit comprising:
- a first light pipe having a first inlet configured to receive radiation from a source and a first outlet;
- a second light pipe having a second inlet configured to receive the radiation from the first light pipe and a second outlet;
- a lens system configured to receive radiation from the second outlet and to output radiation having a predetermined distribution of intensity and irradiance;
- a grating arranged to be illuminated by the radiation exiting the lens system and configured to provide the radiation toward a substrate for measurement by the level sensor.
Dependencies are inferred from the claim text.