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US 10,948,637 B2Granted
Metrology system having an EUV optical unit
AssigneeCarl Zeiss SMT GmbH
InventorsDirk Hellweg, Stefan Mueller, Ralf Gehrke
Life of this patent
Estimating the term…
Abstract
An EUV greyscale filter of an EUV optical unit of a metrology system has a membrane that is at least partly transmissive in regions for EUV light in the wavelength range of between 5 nm and 30 nm. The latter interacts with a whole beam of the EUV light in the operational position of the EUV greyscale filter. This results in a metrology system with extended application possibilities on account of the EUV greyscale filter.
Claims20
A metrology system comprising:
- an EUV light source configured to provide EUV light having a wavelength in a range from 5 nm to 30 nm;
- an EUV optical unit having an EUV greyscale filter, the EUV greyscale filter comprising:
- a membrane that is at least partly transmissive in regions for the EUV light, in which said membrane is configured to interact with a whole beam of the EUV light in an operational position of the EUV greyscale filter located along an optical path of the EUV light at a position between the EUV light source and an object illuminated by the EUV light,
- wherein at least two different transmission levels are realized over a varying thickness of the EUV greyscale filter;
- and
- a spatially resolving detection device for metrology, in which the spatially resolving detection device is configured to detect the EUV light that interacts with the EUV greyscale filter and the object and generate an aerial image of the object.
3 more elements
An apparatus comprising:
- an EUV greyscale filter configured to be used in a metrology system, the EUV greyscale filter comprising a membrane that is at least partly transmissive in regions for EUV light having a wavelength in a range from 5 nm to 30 nm, in which the membrane comprises a first coating having partial layers of discrete thicknesses,
- at a first region of the membrane the first coating has a single partial layer, a lower thickness, and a higher transmission level, and
- at a second region of the membrane the first coating has at least two partial layers, a higher thickness, and a lower transmission level.
An apparatus comprising:
- an EUV greyscale filter configured to be used in a metrology system, the EUV greyscale filter comprising a membrane that is at least partly transmissive in regions for EUV light having a wavelength in a range from 5 nm to 30 nm, in which the membrane comprises a coating that has varying coating point densities,
- at a first region of the membrane the coating has a lower coating point density and a higher transmission level, and
- at a second region of the membrane the coating has a higher coating point density and a lower transmission level.
Dependencies are inferred from the claim text.