Lithography Overlay Correction Using Wafer Subset Fingerprints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithographic processes face inaccuracies due to wafer-to-wafer variations, which are not adequately addressed by existing methods that typically correct errors on a batch or lot basis, leading to reduced accuracy and potential functionality issues in patterned devices.
Innovation Solution
The method involves partitioning substrates into subsets based on performance parameters, determining fingerprints for these parameters, and deriving corrections for subsequent layers to account for variations, thereby improving overlay accuracy and device functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If measurements are performed on a per-batch or per-lot basis to reduce impact on production throughput, then productivity is improved, but manufacturing precision deteriorates due to unaccounted wafer-to-wafer variations
Solution Approach 1:
The patent segments the set of substrates into multiple subsets based on measured performance parameters from previous layers. By partitioning substrates into groups with similar characteristics, the system can apply targeted corrections to each subset rather than treating all substrates uniformly, thereby improving overlay accuracy without requiring measurements on every substrate.
Solution Approach 2:
The patent performs measurements and determines fingerprints for performance parameters on previous layers before processing subsequent layers. By obtaining measurement data and deriving corrections in advance for each subset, the system prepares correction values proactively, enabling accurate overlay control while maintaining production flow without real-time measurement interruptions.
2Manufacturing precision
If known correction methods are applied to complex pattern geometries, then manufacturing precision may be improved, but device functionality deteriorates due to corrections that render devices unfunctional
Solution Approach 1:
The patent applies different correction approaches to different subsets of substrates based on their specific performance characteristics. By tailoring corrections to local subset properties rather than applying uniform corrections across all substrates, the system achieves accurate pattern formation while preserving device functionality for each specific case.
Solution Approach 2:
The patent uses measured performance parameters from previous layers as feedback to derive corrections for subsequent layers. By continuously measuring and adjusting based on actual substrate performance, the system optimizes pattern accuracy while avoiding excessive corrections that could compromise device functionality.
3Manufacturing precision
If individual substrate variations are accounted for through detailed measurements, then manufacturing precision is improved, but productivity decreases due to increased measurement time
Solution Approach 1:
The patent reduces measurement burden by segmenting substrates into subsets and performing measurements on representative samples from each subset rather than every substrate. This approach captures wafer-to-wafer variations effectively while minimizing measurement time and maintaining production throughput.
Solution Approach 2:
The patent determines fingerprints for performance parameters on previous layers and uses these as copies or proxies to predict and correct variations in subsequent layers. By measuring once and reusing the fingerprint information across multiple layers and similar substrates, the system achieves high overlay accuracy without repeated measurements on every substrate.
Data Source
AI summary
A lithographic process is performed on a set of semiconductor substrates consisting of a plurality of substrates. As part of the process, the set of substrates is partitioned into a number of subsets. The partitioning may be based on a set of characteristics associated with a first layer on the substrates. A fingerprint of a performance parameter is then determined for at least one substrate of the set of substrates. Under some circumstances, the fingerprint is determined for one substrate of each subset of substrates. The fingerprint is associated with at least the first layer. A correction for the performance parameter associated with an application of a subsequent layer is then derived, the derivation being based on the determined fingerprint and the partitioning of the set of substrates.