Lithographic processing optimization based on hypersampled correlations
First Claim
1. A method of optimizing lithographic processing to achieve substrate uniformity, comprising:
- deriving correlation information indicative of photoresist behavior, comprising;
exposing a pattern onto a plurality of subfields of a plurality of substrates such that, for each of said substrates, said subfields are repeatedly exposed with the pattern at different focal positions of a lithographic exposure apparatus,processing each of said substrates at different target processing conditions,measuring attributes of each of said subfields within each of said processed substrates,determining a characteristic for each of said subfields based on said measured attributes, said characteristic representative of photoresist behavior, andextracting correlation information regarding said subfield characteristics and said different target processing conditions;
detecting non-uniformities in a subsequent substrate, comprising;
exposing said pattern onto a plurality of subfields of said subsequent substrate such that said subfields are repeatedly exposed with the pattern at different focal positions of said lithographic exposure apparatus,processing said subsequent substrate at a production processing condition,measuring attributes of said subfields within said processed subsequent substrate,determining said characteristic for each of said subfields within said processed subsequent substrate based on said measured attributes, andidentifying differences among said subfield characteristics of said processed subsequent substrate; and
adjusting said production processing condition based on said correlation information.
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Abstract
A method of optimizing lithographic processing to achieve substrate uniformity, is presented herein. In one embodiment, The method includes deriving hyper-sampled correlation information indicative of photoresist behavior for a plurality of wafer substrates processed at pre-specified target processing conditions. The derivation includes micro-exposing subfields of the substrates with a pattern, processing the substrates at the various target conditions, determining photoresist-related characteristics of the subfields (e.g., Bossung curvatures), and extracting correlation information regarding the subfield characteristics and the different target processing conditions to relate the target conditions as a function of subfield characteristics. The method then detects non-uniformities in a micro-exposed subsequent substrate-processed under production-level processing conditions and exploits the correlation information to adjust the production-level conditions and achieve uniformity across the substrate.
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Citations
27 Claims
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1. A method of optimizing lithographic processing to achieve substrate uniformity, comprising:
deriving correlation information indicative of photoresist behavior, comprising; exposing a pattern onto a plurality of subfields of a plurality of substrates such that, for each of said substrates, said subfields are repeatedly exposed with the pattern at different focal positions of a lithographic exposure apparatus, processing each of said substrates at different target processing conditions, measuring attributes of each of said subfields within each of said processed substrates, determining a characteristic for each of said subfields based on said measured attributes, said characteristic representative of photoresist behavior, and extracting correlation information regarding said subfield characteristics and said different target processing conditions; detecting non-uniformities in a subsequent substrate, comprising; exposing said pattern onto a plurality of subfields of said subsequent substrate such that said subfields are repeatedly exposed with the pattern at different focal positions of said lithographic exposure apparatus, processing said subsequent substrate at a production processing condition, measuring attributes of said subfields within said processed subsequent substrate, determining said characteristic for each of said subfields within said processed subsequent substrate based on said measured attributes, and identifying differences among said subfield characteristics of said processed subsequent substrate; and adjusting said production processing condition based on said correlation information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of optimizing uniformity in lithographic processing, comprising:
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exposing repeatedly a pattern at different exposure conditions on a subfield of a substrate with a lithographic projection apparatus, processing said substrate at a production processing condition, measuring attributes of said subfield of said processed substrate, determining a characteristic of said subfield of said processed substrate based on said measured attributes, identifying differences between said calculated characteristics; determining differences in production processing condition on the basis of said identified differences, and; adjusting said production processing condition based on said determined differences. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method of deriving correlation information indicative of photoresist behavior by:
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exposing repeatedly a pattern at different exposure conditions on subfields of a plurality of calibration substrates with a lithographic projection apparatus, processing each of said calibration substrates at different target processing conditions, measuring attributes of said subfields, determining a characteristic for each of said subfields based on said measured attributes, said characteristic representative of photoresist behavior, and extracting correlation information regarding said subfield characteristics and said different target processing conditions. - View Dependent Claims (20, 21, 22)
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23. A method of optimizing lithographic processing to achieve substrate uniformity, comprising:
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deriving correlation information indicative of photoresist behavior by micro-exposing a pattern at different focal positions onto a plurality of subfields within a plurality of substrates, processing each of said substrates at different target processing conditions, measuring attributes of each of said subfields within each of said processed substrates, determining a Bossung curvature characteristic for each of said subfields based on said measured attributes, and correlating each Bossung curvature characteristic to said different target processing conditions; detecting non-uniformities in a subsequent substrate by micro-exposing said pattern at different focal positions onto a plurality of subfields within said subsequent substrate, processing said subsequent substrate at a production processing condition that is consistent with at least one of said different target processing conditions, measuring attributes of said subfields within said processed subsequent substrate, determining said Bossung curvature characteristic for each of said subfields within said processed subsequent substrate based on said measured attributes, and identifying differences among said subfield characteristics of said processed subsequent substrate; and adjusting said production processing condition based on said correlation information by determining an expected characteristic value Bossung curvature characteristic for each of said subfields within said processed subsequent substrate, referring to said correlation information to indicate a corresponding production processing condition, and adjusting said processing to achieve said indicated corresponding production processing condition. - View Dependent Claims (24, 25, 26, 27)
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Specification