Baseline overlay control with residual noise reduction
First Claim
1. A method of using a control module to control a scanning/stepping function of a lithographic apparatus, the method comprising:
- exposing a first layer on a wafer and measuring first overlay vectors of alignment registration marks at multiple locations relative to alignment registration marks of a baseline reference wafer;
reworking and exposing the first layer a second time and measuring second overlay vectors relative to the alignment registration marks of the baseline reference wafer;
subtracting the second overlay vectors from the first overlay vectors to obtain overlay vector differences at each of the multiple locations within the first layer;
applying a first pre-correction factor based on the overlay vector differences to the scanning/stepping function, wherein the pre-correction factor has a magnitude of an opposite sign to the overlay vector difference at each of the multiple locations; and
exposing the second layer.
1 Assignment
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Accused Products
Abstract
Systems, methods and computer program products generally include a vector by vector subtraction method per wafer. A first layer is exposed to form a pattern image on a wafer and the overlay data of alignment registration marks at multiple locations relative to alignment registration marks of a baseline reference are measured. The first layer is then reworked and exposed to form the same pattern image and the overlay data of alignment registration marks at multiple locations relative to alignment registration marks of a first layer are measured. The overlay data of the reworked first layer is subtracted from the overlay data of the first layer to provide an overlay difference at each of the multiple locations. The overlay difference is converted to a pre-correction factor of a magnitude opposite that of the overlay difference and is applied to exposure of a second layer provided on the first layer.
31 Citations
19 Claims
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1. A method of using a control module to control a scanning/stepping function of a lithographic apparatus, the method comprising:
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exposing a first layer on a wafer and measuring first overlay vectors of alignment registration marks at multiple locations relative to alignment registration marks of a baseline reference wafer; reworking and exposing the first layer a second time and measuring second overlay vectors relative to the alignment registration marks of the baseline reference wafer; subtracting the second overlay vectors from the first overlay vectors to obtain overlay vector differences at each of the multiple locations within the first layer; applying a first pre-correction factor based on the overlay vector differences to the scanning/stepping function, wherein the pre-correction factor has a magnitude of an opposite sign to the overlay vector difference at each of the multiple locations; and exposing the second layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A non-transitory computer program stored on a machine-readable medium, and including instructions for exercising control over a lithographic apparatus so as to perform a method, comprising:
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projecting a first patterned radiation beam as a pattern image onto a first layer on a substrate along a scan path, the scan path being defined by a trajectory in a scanning direction of an exposure field; measuring first overlay vectors of alignment registration marks at multiple locations relative to alignment registration marks of a baseline reference wafer; reworking the first layer by removing the first layer and redepositing the first layer onto the substrate; projecting the first patterned radiation beam as the pattern image onto the reworked first layer along the scan path; measuring second overlay vectors at multiple locations relative to the alignment registration marks of the baseline reference wafer; subtracting the second overlay vectors from the first overlay vectors to obtain overlay vector differences at each of the multiple locations within the first layer; calculating a first pre-correction factor based on the overlay vector difference, wherein the first pre-correction factor has a magnitude of an opposite sign to the overlay vector differences at each of the multiple locations; and projecting a second patterned radiation beam as a pattern image onto a second layer on a substrate along the scan path, wherein the first pre-correction factor is applied to the patterned radiation beam to provide a vector by vector correction at each of the multiple locations. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A system for enhanced overlay control by residual noise reduction, the system comprising:
an overlay metrology tool in communication with a scanner stability module to control a scanning/stepping function of a lithographic apparatus, wherein the overlay metrology tool is configured to calculate a positional offset of an alignment registration mark in a first layer, wherein the positional offset comprises an overlay vector difference calculated by subtracting first overlay vectors of alignment registration marks measured at multiple locations in the first layer relative to alignment registration marks of a baseline reference wafer from second overlay vectors measured at the multiple locations in a reworked first layer relative to the alignment registration marks in the baseline reference, wherein the positional offset provides a vector by vector correction at each of the multiple locations. - View Dependent Claims (18, 19)
Specification