Focus measurements using scatterometry metrology
First Claim
1. A target design comprising:
- a plurality of structures including a plurality of elements, wherein the plurality of structures are arranged based on a first pitch in a first direction along a first axis, wherein the plurality of elements are arranged based on a second pitch in a second direction along a second axis substantially perpendicular to the first axis,wherein the plurality of elements includes a plurality of focus-insensitive elements arranged in a focus-insensitive pattern, wherein the second pitch includes a spatial distance between adjacent focus-insensitive elements of the plurality of focus-insensitive elements,wherein the plurality of elements includes a plurality of focus-sensitive elements arranged in a focus-sensitive pattern, wherein a set of the plurality of focus-sensitive elements is positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements,wherein the set of the plurality of focus-sensitive elements positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements are arranged based on a third pitch, wherein the third pitch includes a spatial distance smaller than the spatial distance of the second pitch.
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Accused Products
Abstract
Target designs and methods are provided, which relate to periodic structures having elements recurring with a first pitch in a first direction. The elements are periodic with a second pitch along a second direction that is perpendicular to the first direction and are characterized in the second direction by alternating, focus-sensitive and focus-insensitive patterns with the second pitch. In the produced targets, the first pitch may be about the device pitch and the second pitch may be several times larger. The first, focus-insensitive pattern may be produced to yield a first critical dimension and the second, focus-sensitive pattern may be produced to yield a second critical dimension that may be equal to the first critical dimension only when specified focus requirements are satisfied, or provide scatterometry measurements of zeroth as well as first diffraction orders, based on the longer pitch along the perpendicular direction.
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Citations
22 Claims
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1. A target design comprising:
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a plurality of structures including a plurality of elements, wherein the plurality of structures are arranged based on a first pitch in a first direction along a first axis, wherein the plurality of elements are arranged based on a second pitch in a second direction along a second axis substantially perpendicular to the first axis, wherein the plurality of elements includes a plurality of focus-insensitive elements arranged in a focus-insensitive pattern, wherein the second pitch includes a spatial distance between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the plurality of elements includes a plurality of focus-sensitive elements arranged in a focus-sensitive pattern, wherein a set of the plurality of focus-sensitive elements is positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the set of the plurality of focus-sensitive elements positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements are arranged based on a third pitch, wherein the third pitch includes a spatial distance smaller than the spatial distance of the second pitch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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generating a target design, wherein the target design includes a plurality of structures including a plurality of elements, wherein the plurality of structures are arranged based on a first pitch in a first direction along a first axis, wherein the plurality of elements are arranged based on a second pitch in a second direction along a second axis substantially perpendicular to the first axis, wherein the plurality of elements includes a plurality of focus-insensitive elements arranged in a focus-insensitive pattern, wherein the second pitch includes a spatial distance between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the plurality of elements includes a plurality of focus-sensitive elements arranged in a focus-sensitive pattern, wherein a set of the plurality of focus-sensitive elements is positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the set of the plurality of focus-sensitive elements positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements are arranged based on a third pitch, wherein the third pitch includes a spatial distance smaller than the spatial distance of the second pitch; and verifying a focus of a lithography tool by measuring the focus-sensitive pattern. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A target design comprising:
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a plurality of structures including a plurality of elements, wherein the plurality of structures are arranged based on a first pitch and a second pitch in a first direction along a first axis, wherein the plurality of elements are arranged based on a third pitch in a second direction along a second axis substantially perpendicular to the first axis, wherein the first pitch includes a spatial distance between adjacent structures of the plurality of structures, wherein the second pitch includes a spatial distance between non-adjacent structures of the plurality of structures, wherein the second pitch is larger than the first pitch, wherein the plurality of elements includes a plurality of focus-insensitive elements arranged in a focus-insensitive pattern, wherein the third pitch includes a spatial distance between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the plurality of elements includes a plurality of focus-sensitive elements arranged in a focus-sensitive pattern, wherein a set of the plurality of focus-sensitive elements is positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements, wherein the set of the plurality of focus-sensitive elements positioned between adjacent focus-insensitive elements of the plurality of focus-insensitive elements are arranged based on a fourth pitch, wherein the fourth pitch includes a spatial distance smaller than the spatial distance of the third pitch.
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Specification