Lithographic apparatus, substrate and device manufacturing method
First Claim
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1. A method comprising:
- illuminating a target structure using a spot size that is larger than the target structure, wherein the target structure includes a progressive optical contrast transition at peripheral edges of the target structure; and
measuring a diffraction pattern of the target structure, wherein a diffraction effect at the peripheral edges of the target structure is substantially reduced by the progressive optical contrast transition.
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Abstract
A method uses a lithographic apparatus to form an inspection target structure upon a substrate. The method comprises forming the periphery of the inspection target structure so as to provide a progressive optical contrast transition between the inspection target structure and its surrounding environment. This may be achieved by providing a progressive change in the optical index at the periphery of the target structure.
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Citations
29 Claims
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1. A method comprising:
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illuminating a target structure using a spot size that is larger than the target structure, wherein the target structure includes a progressive optical contrast transition at peripheral edges of the target structure; and measuring a diffraction pattern of the target structure, wherein a diffraction effect at the peripheral edges of the target structure is substantially reduced by the progressive optical contrast transition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A substrate comprising:
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a target structure formed thereon by a lithographic process, the target structure including a progressive optical contrast transition at peripheral edges of the target structure, wherein the progressive optical contrast transition is configured to reduce a diffraction effect at the peripheral edges of the target structure when the target structure is illuminated with a spot size that is larger than the target structure. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A non-transitory computer-readable storage device having instructions stored thereon, execution of which, by a computing device, causes the computing device to control an inspection apparatus to perform operations comprising:
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illuminating a target structure using a spot size that is larger than the target structure, wherein the target structure includes a progressive optical contrast transition at peripheral edges of the target structure; and measuring a diffraction pattern of the target structure, wherein a diffraction effect at the peripheral edges of the target structure is substantially reduced by the progressive optical contrast transition.
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22. An inspection apparatus, comprising:
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an optical system configured to direct a radiation beam onto a target structure patterned on a wafer, wherein the target structure includes a progressive optical contrast transition at peripheral edges of the target structure; and one or more sensors configured to receive light from the target structure, wherein a spot size of the radiation beam is larger than the target structure, and wherein a diffraction effect at the peripheral edges of the target structure is substantially reduced by the progressive optical contrast transition. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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Specification