Field-Sensitive Overlay Targets for Field-to-Field Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in monitoring and controlling field-to-field errors and overlay errors across multiple exposure fields, leading to decreased throughput and accuracy in metrology measurements.
Innovation Solution
The implementation of field-sensitive overlay targets that allow for simultaneous measurement of both overlay and field-to-field errors using a common metrology target, which are designed to be sensitive to variations between overlapping and adjacent exposure fields, enabling the use of existing or new overlay measurement techniques to provide accurate data for correcting lithography tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate targets and measurement techniques are used for overlay metrology and field-to-field metrology, then measurement precision is improved, but device complexity and fabrication throughput are worsened
Solution Approach 1:
The patent combines overlay metrology targets and field-to-field metrology targets into a single integrated metrology target structure. The target includes both overlay features (for measuring alignment between layers) and field-to-field features (for measuring exposure field placement accuracy), allowing both types of measurements to be performed simultaneously using the same physical target and measurement system, thereby reducing system complexity while maintaining measurement precision
Solution Approach 2:
The integrated metrology target serves multiple functions: it provides overlay measurement capabilities for monitoring alignment between different patterned layers, and simultaneously provides field-to-field measurement capabilities for monitoring exposure field placement accuracy. This multi-functional target eliminates the need for separate specialized targets and measurement techniques, improving fabrication throughput while maintaining both types of metrology precision
2Measurement precision
If multiple metrology targets are placed on a sample, then measurement precision is improved, but productivity is worsened
Solution Approach 1:
The patent merges multiple measurement functions into a single metrology target, allowing both overlay and field-to-field measurements to be performed on one target rather than requiring multiple separate targets. This reduces the total number of metrology targets needed on each sample, thereby improving fabrication throughput while maintaining comprehensive measurement precision for both overlay alignment and exposure field placement
3Manufacturing precision
If field-to-field errors are monitored and controlled, then manufacturing precision is improved, but device complexity is worsened
Solution Approach 1:
The patent integrates field-to-field measurement capabilities directly into the overlay metrology target structure. The target includes specific features designed to measure exposure field placement accuracy (field-to-field errors) alongside traditional overlay features. This integration allows field-to-field monitoring to be performed using the same measurement system and target as overlay metrology, reducing device complexity while improving manufacturing precision for exposure field placement
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A metrology system may include a controller coupled to a metrology tool. The controller may receive a metrology target design including at least a first feature formed by exposing a first exposure field on a sample with a lithography tool, and at least a second feature formed by exposing a second exposure field on the sample with the lithography tool, where the second exposure field overlaps the first exposure field at a location of a metrology target on the sample. The controller may further receive metrology data associated with the metrology target fabricated according to the metrology target design, determine one or more fabrication errors during fabrication of the metrology target based on the metrology data, and generate correctables to adjust one or more fabrication parameters of the lithography tool in one or more subsequent lithography steps based on the one or more fabrication errors.