Lithographic Focus and Dose Measurement Using A 2-D Target
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Accused Products
Abstract
In order to determine whether an exposure apparatus is outputting the correct dose of radiation and its projection system is focusing the radiation correctly, a test pattern is used on a mask for printing a specific marker onto a substrate. This marker is then measured by an inspection apparatus, such as a scatterometer, to determine whether there are errors in focus and dose and other related properties. The test pattern is configured such that changes in focus and dose may be easily determined by measuring the properties of a pattern that is exposed using the mask. The test pattern may be a 2D pattern where physical or geometric properties, e.g., pitch, are different in each of the two dimensions. The test pattern may also be a one-dimensional pattern made up of an array of structures in one dimension, the structures being made up of at least one substructure, the substructures reacting differently to focus and dose and giving rise to an exposed pattern from which focus and dose may be determined.
95 Citations
78 Claims
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1-64. -64. (canceled)
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65. A method comprising:
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printing a marker on a substrate using an exposure apparatus and a mask, the mask including a pattern for creating the marker, the pattern comprising an array of structures, the array having a pitch in one direction that is resolvable by the exposure apparatus and a pitch in a second direction different front the first direction that is not resolvable by the exposure apparatus; and measuring a property of the substrate that has been exposed by the exposure apparatus and the mask, the measuring comprising; projecting a radiation beam onto the marker on the substrate; detecting radiation reflected from the marker on the substrate; and determining, from the properties of the reflected radiation, the at least one of focus and dose related properties of the exposure apparatus. - View Dependent Claims (66, 67, 68)
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69. A mask comprising:
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a pattern for printing a marker on a substrate, wherein the pattern comprises an array of structures, and wherein the array has a first pitch in one direction that is resolvable by an exposure apparatus and a second pitch in a second direction different from the first direction that is not resolvable by the exposure apparatus. - View Dependent Claims (70, 71, 72, 73)
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74. An system comprising:
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a mask including a pattern configured to print a marker on a substrate using an exposure apparatus, the pattern comprising an array of structures, the array having a pitch in one direction that is resolvable by the exposure apparatus to be measured and a pitch in a second direction different from the first direction that is not resolvable by the exposure apparatus to be measured; and an inspection apparatus configured to measure a property of the substrate on which the marker has been printed by the exposure apparatus using the mask, the inspection apparatus comprising; a radiation source; a projection system configured to direct radiation from the radiation source onto the marker; a detector configured to detect radiation reflected from the marker; and a processor configured to determine, from the properties of the reflected radiation, the at least one of focus and dose related properties of the exposure apparatus. - View Dependent Claims (75)
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76. An apparatus configured to measure a property of a substrate on which a marker has been printed by an exposure apparatus using a mask containing a pattern, the marker having been printed using a pattern that comprises an array of structures, the array having a pitch in one direction that is resolved in the marker and a pitch in a second direction different from the first direction that is not resolved in the marker, the inspection apparatus comprising:
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a radiation source; a projection system configured to direct radiation from the radiation source onto the marker; a detector configured to detect radiation reflected from the marker; and a processor configured to determine properties of the marker from the detected radiation, and, from the properties of the reflected radiation, focus and/or dose related properties of the exposure apparatus used to print the marker. - View Dependent Claims (77)
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78. A lithographic cell comprising:
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a coater arranged to coat a substrate with a radiation sensitive layer; a lithographic apparatus configured to expose an image onto the radiation sensitive layer of the substrate coated by the coater; a developer configured to develop the image exposed by the lithographic apparatus; and an inspection apparatus configured to measure a property of a substrate on which a marker has been printed by an exposure apparatus using a mask containing a pattern, the marker having been printed using a pattern that comprises an array of structures, the array having a pitch in one direction that is resolved in the marker and a pitch in a second direction different from the first direction that is not resolved in the marker, the inspection apparatus comprising, a radiation source, a projection system configured to direct radiation from the radiation source onto the marker, a detector configured to detect radiation reflected from the marker, and a processor configured to determine properties of the marker from the detected radiation, and, from the properties of the reflected radiation, focus or dose related properties of the exposure apparatus used to print the marker.
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Specification