Metrology apparatus
AssigneeASML Netherlands B.V.
InventorsMarinus Johannes Maria Van Dam, Arie Jeffrey Den Boef, Nitesh Pandey
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Abstract
A metrology apparatus for determining a characteristic of interest of a structure on a substrate, the apparatus comprising: a radiation source for generating illumination radiation; at least two illumination branches for illuminating the structure on the substrate, the illumination branches being configured to illuminate the structure from different angles; and a radiation switch configured to receive the illumination radiation and transfer at least part of the radiation to a selectable one of the at least two illumination branches.
Claims15
A metrology apparatus for determining a characteristic of interest of a structure on a substrate, the apparatus comprising:
- a radiation source configured to generate illumination radiation;
- at least two illumination branches configured to illuminate the structure on the substrate, the illumination branches being configured to illuminate the structure from different angles;
- and
- a radiation switch configured to receive the illumination radiation and transfer at least part of the radiation to a selectable one of the at least two illumination branches, wherein the radiation switch comprises:
- a Pockels cell configured to control a polarization direction of the illumination radiation and to output polarization controlled illumination radiation, and
- a polarizing beam splitter optically downstream of the Pockels cell and configured to, depending on the polarization direction of the polarization controlled illumination radiation, transmit the polarization controlled illumination radiation to a first one of the at least two illumination branches or reflect the polarization controlled illumination radiation to a second one of the illumination branches.
A method for determining a parameter of interest of a structure on a substrate the method comprising:
- generating illumination radiation;
- receiving the illumination radiation at a radiation switch that transfers at least part of the radiation to a selectable one of the at least two illumination branches;
- sequentially illuminating the structure by the least two illumination branches from different angles;
- collecting at least a portion of radiation diffracted from the structure;
- and
- receiving and obtaining a recording of the collected diffracted radiation at an image sensor, wherein the radiation switch uses:
- a Pockels cell configured to control a polarization direction of the illumination radiation and to output polarization controlled illumination radiation, and
- a polarizing beam splitter optically downstream of the Pockels cell and configured to, depending on the polarization direction of the polarization controlled illumination radiation, transmit the polarization controlled illumination radiation to a first one of the at least two illumination branches or reflect the polarization controlled illumination radiation to a second one of the illumination branches.
A lithographic cell comprising:
- a metrology apparatus for determining a characteristic of interest of a structure on a substrate, the apparatus comprising:
- a radiation source configured to generate illumination radiation;
- at least two illumination branches configured to illuminate the structure on the substrate, the illumination branches being configured to illuminate the structure from different angles;
- and
- a radiation switch configured to receive the illumination radiation and transfer at least part of the radiation to a selectable one of the at least two illumination branches, wherein the radiation switch comprises:
- a Pockels cell configured to control a polarization direction of the illumination radiation and to output polarization controlled illumination radiation, and
- a polarizing beam splitter optically downstream of the Pockels cell and configured to, depending on the polarization direction of the polarization controlled illumination radiation, transmit the polarization controlled illumination radiation to a first one of the at least two illumination branches or reflect the polarization controlled illumination radiation to a second one of the illumination branches.
Dependencies are inferred from the claim text.