PATENT CLAIM ANALYSIS

Application Number: 15967861
Application Type: Utility
Filing Date: 2018-05
Publication Date: 2018-11
Patent Classification: ["355", "018000"]

Abstract:
An overlay metrology target (600, 900, 1000) contains a plurality of overlay gratings (932-935) formed by lithography. First diffraction signals (740(1)) are obtained from the target, and first asymmetry values (As) for the target structures are derived. Second diffraction signals (740(2)) are obtained from the target, and second asymmetry values (As′) are derived. The first and second diffraction signals are obtained using different capture conditions and/or different designs of target structures and/or bias values. The first asymmetry signals and the second asymmetry signals are used to solve equations and obtain a measurement of overlay error. The calculation of overlay error makes no assumption whether asymmetry in a given target structure results from overlay in the first direction, in a second direction or in both directions. With a suitable bias scheme the method allows overlay and other asymmetry-related properties to be measured accurately, even in the presence of two-dimensional overlay structure.

Claim (Index 66):
A method of determining overlay performance of a lithographic process, the method comprising:\n (a) obtaining a plurality of target structures that have been formed by the lithographic process, each target structure comprising a set of first features arranged periodically in at least a first direction and a set of second features arranged periodically in at least the first direction and being subject to overlay error associated with the second features relative to the first features, (b) using a detection system to detect first diffraction signals comprising selected portions of radiation diffracted by at least a subset of the target structures; (c) using the detection system to detect second diffraction signals comprising selected portions of radiation diffracted by at least a subset of the overlay targets; (d) processing asymmetry information derived from the first diffraction signals and the second diffraction signals to calculate at least a measurement of the overlay error in at least the first direction, wherein said target structures have been formed with programmed offsets in the placement of the second features relative to the first features in addition to said overlay error, the programmed offsets within each subset differing in both the first direction and in a second direction, the first and second directions being non-parallel, and wherein the calculation of overlay error in step (d) combines said asymmetry information with knowledge of the programmed offsets while making no assumption whether asymmetry in a given target structure results from relative displacement of the second features in the first direction, in the second direction or both directions.

Metadata:
- Claim Count in Document: 32.0
- Percentile: 93.0
- Lexical Diversity: 2.18072
- Patent Class: 355.0
- Transitional Phrase Type: open
- Component Type: 1
- Foreign Priority: True
- Related Applications: ['15834763', '15013340', '15186031', '15875156', '15032507']

Analysis Scores:
- 35 USC 101 Eligibility (BERT): 0.7273422852304147
- 35 USC 102 Novelty (BERT): 0.4947307763941478
- Combined Prediction Score: 0.704081134346788
- Mean Citation Score: 291.46837000000005
- Max Citation Score: 308.44202
- Similarity Product: 260.3596958342242

Labels:
- Claim Label 101: 1
- Claim Label 102: 0
- Claim Label 103: 1
- Claim Label 112: 0
- Combined Label: 0
- Label 101 Adjusted: 1

Dataset: test