Lithographic Metrology Sensor Arrays for High-Throughput Error Detection
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Solution Overview
Problem
Existing metrology techniques for detecting and quantifying manufacturing inaccuracies in lithographic processes are low throughput, require complex and expensive tooling, and are susceptible to inherent noise and errors, limiting the frequency and accuracy of process control and monitoring in semiconductor manufacturing.
Innovation Solution
A method and system that utilizes an array of metrology sensors on a substrate, which produce discrete physical events dependent on manufacturing inaccuracies, allowing for direct detection and quantification of edge placement errors through imaging before digitization, independent of imaging technique or computational processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing metrology techniques are used to detect manufacturing inaccuracies, then measurement capability is provided, but throughput is low and costs are high
Solution Approach 1:
The patent segments the metrology function into two distinct parts: (1) a lithographic apparatus that writes patterns containing embedded sensor structures directly onto the substrate during normal fabrication, and (2) a separate readout system that images these patterns to extract manufacturing inaccuracy data. This segmentation allows the high-precision measurement function to be integrated into the fabrication process itself, enabling high throughput without sacrificing measurement capability.
2Measurement precision
If complex metrology tooling is used to achieve accurate measurements, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the lithographic apparatus multi-functional by enabling it to perform both its primary function of writing functional device patterns and a secondary function of writing embedded sensor patterns for metrology. The same lithographic system used for manufacturing also creates the measurement references, eliminating the need for separate complex metrology tooling and reducing overall system complexity and cost.
Solution Approach 2:
The patent creates simplified optical copies of the nanometric features by imaging them with a separate readout system. Instead of using complex electron microscopy or other advanced characterization tools, the system uses optical imaging to capture images of the lithographically-written patterns, extracting manufacturing inaccuracy information from these optical copies rather than requiring direct nanometric measurement.
3Reliability
If traditional imaging-based metrology is used, then manufacturing inaccuracies can be detected, but systematic errors and noise from the imaging system affect measurement reliability
Solution Approach 1:
The patent inverts the traditional metrology approach by not trying to directly measure nanometric features with high-resolution imaging systems prone to systematic errors. Instead, it writes the manufacturing inaccuracy information directly into the patterns using the lithographic apparatus, then uses a separate readout system to image these patterns. The manufacturing inaccuracies are encoded in the patterns themselves rather than being extracted through complex imaging and computational analysis, thereby avoiding propagation of imaging system errors.
Data Source
AI summary
A method for detecting and/or quantifying manufacturing inaccuracies made by a lithographic process includes: providing at least one design for fabrication of structures on a substrate using a set of lithographic processes. The structures define an array of metrology sensors, each sensor producing one of a known and finite set of possible distinct physical events upon application of a physical process. The produced physical event is unknown before application of the physical process, dependent on manufacturing inaccuracies generated by at least one of the set of lithographic processes, and is a displaced state of the fabricated structure, or has one or more physical entities associated with the fabricated structures present that were absent before the application of the physical process. The method includes applying the set of lithographical processes; applying the physical process; and reading out the produced physical events of all sensors. A metrology system is also provided.