Apparatus for determining an overlay error and critical dimensions in a semiconductor structure by means of scatterometry
First Claim
1. An apparatus for obtaining information on critical dimensions and overlay accuracy of features formed in a semiconductor structure, wherein the semiconductor structure includes a first diffracting pattern oriented with respect to a first direction and a second diffracting pattern oriented with respect to a second direction, the apparatus comprising:
- a light source for emitting at least one light beam;
a first plurality of deflecting elements defining a first optical path in a first plane of incidence corresponding to the first direction, and a second plurality of deflecting elements defining a second optical path in a second plane of incidence corresponding to the second direction;
a detector optically connectable to the first and second optical paths to receive a light beam diffracted by the first and the second diffracting patterns, respectively; and
a first partially reflecting mirror directing a first portion of an incident light beam into the first optical path and directing a second portion of the incident light beam into the second optical path, wherein a common transmittance of the first partially reflecting mirror and of a transmissive element arranged in the second optical path is substantially equal to a reflectivity of the first partially reflecting mirror.
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Accused Products
Abstract
An apparatus for obtaining information on critical dimensions and overlay accuracy of features in a semiconductor structure comprises a light source, a detector and an optical means defining a first optical path and a second optical path. The first optical path and the second optical path are oriented in correspondence with the respective orientations of diffracting patterns provided on the semiconductor structure to obtain the required information without the necessity of rotating the semiconductor structure. This insures a significantly higher throughput.
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Citations
14 Claims
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1. An apparatus for obtaining information on critical dimensions and overlay accuracy of features formed in a semiconductor structure, wherein the semiconductor structure includes a first diffracting pattern oriented with respect to a first direction and a second diffracting pattern oriented with respect to a second direction, the apparatus comprising:
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a light source for emitting at least one light beam;
a first plurality of deflecting elements defining a first optical path in a first plane of incidence corresponding to the first direction, and a second plurality of deflecting elements defining a second optical path in a second plane of incidence corresponding to the second direction;
a detector optically connectable to the first and second optical paths to receive a light beam diffracted by the first and the second diffracting patterns, respectively; and
a first partially reflecting mirror directing a first portion of an incident light beam into the first optical path and directing a second portion of the incident light beam into the second optical path, wherein a common transmittance of the first partially reflecting mirror and of a transmissive element arranged in the second optical path is substantially equal to a reflectivity of the first partially reflecting mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for obtaining information on critical dimensions and overlay accuracy of features formed in a semiconductor structure, wherein the semiconductor structure includes a first diffracting pattern oriented with respect to a first direction and a second diffracting pattern oriented with respect to a second direction, the apparatus comprising:
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a light source for emitting at least one light beam;
a first optical path and second optical path;
a detector optically connectable to the first and second optical paths to receive a light beam diffracted by the first and the second diffracting patterns, respectively;
a first optical fiber with a first end thereof optically coupled to the light source to at least partially define said first optical path;
a second optical fiber with a first end thereof optically coupled to the detector to at least partially define said second optical path; and
a switch mechanically coupled to a second end of the first and second optical fibers, respectively;
wherein a first position of the switch defines the first optical path and a second position defines the second optical path.- View Dependent Claims (11)
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12. An apparatus adapted for obtaining information on critical dimensions and overlay accuracy of features formed in a semiconductor structure, wherein the semiconductor structure includes a first diffracting pattern oriented with respect to a first direction and a second diffracting pattern oriented with respect to a second direction, the apparatus comprising:
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means for emitting at least one light beam;
means for defining a first optical path and second optical path;
means for receiving a light beam diffracted by the first and the second diffracting patterns, said means for receiving said light beam comprises a detector optically connectable to the first and second optical path;
a first optical fiber with a first end thereof optically coupled to the means for emitting at least one light beam;
a second optical fiber with a first end thereof optically counted to the detector; and
a switch mechanically coupled to a second end of the first and second optical fibers, respectively, wherein a first position of the switch defines the first optical path and a second position defines the second optical path. - View Dependent Claims (13, 14)
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Specification