ROTATIONAL MULTI-LAYER OVERLAY MARKS, APPARATUS, AND METHODS
First Claim
1. A semiconductor target for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, the target comprising:
- a plurality of first structures that are invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures; and
a plurality of second structures that are invariant for a plurality of second rotation angles with respect to a second COS of the second structures,wherein the first rotation angles differ from the second rotation angles,wherein the first structures and the second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate.
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Abstract
In one embodiment, a semiconductor target for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate is disclosed. The target comprises at least a plurality of first structures that are invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures and a plurality of second structures that are invariant for a plurality of second rotation angles with respect to a second COS of the second structures. The first rotation angles differ from the second rotation angles, and first structures and second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate.
18 Citations
21 Claims
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1. A semiconductor target for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, the target comprising:
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a plurality of first structures that are invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures; and a plurality of second structures that are invariant for a plurality of second rotation angles with respect to a second COS of the second structures, wherein the first rotation angles differ from the second rotation angles, wherein the first structures and the second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, the method comprising:
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acquiring an image of a plurality of first structures that are designed to be invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures and of a plurality of second structures that are designed to be invariant for a plurality of second rotation angles with respect to a second COS of the second structures, wherein the first rotation angles differ from the second rotation angles and wherein the first structures and the second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate; determining the first COS of the first structures based on rotating the image by the first rotation angles and determining the second COS of the second structures based on rotating the image by the second rotation angles; and comparing the determined first and second COS to determine whether there is an overlay error between the first and second structures that is out of specification. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of manufacturing a semiconductor target for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, comprising:
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forming a plurality of first structures of a target that are invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures; and forming a plurality of second structures the target that are invariant for a plurality of second rotation angles with respect to a second COS of the second structures, wherein the first rotation angles differ from the second rotation angles, wherein the first structures and the second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate. - View Dependent Claims (18)
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19. An apparatus for determining overlay error, if any, between two or more successive layers of a substrate or between two or more separately generated patterns on a single layer of a substrate, the apparatus comprising:
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an optical assembly for acquiring an image of a plurality of first structures that are designed to be invariant for a plurality of first rotation angles with respect to a first center of symmetry (COS) of the first structures and of a plurality of second structures that are designed to be invariant for a plurality of second rotation angles with respect to a second COS of the second structures, wherein the first rotation angles differ from the second rotation angles and wherein the first structures and the second structures are formed on different layers of the substrate or separately generated patterns on a same layer of the substrate; at least one memory; and at least one processor, wherein the at least one memory and processor are configured for performing the following operations; determining the first COS of the first structures based on rotating the image by the first rotation angles and determining the second COS of the second structures based on rotating the image by the second rotation angles; and comparing the determined first and second COS to determine whether there is an overlay error between the first and second structures that is out of specification. - View Dependent Claims (20, 21)
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Specification