One-Dimensional Overlay Marks for Flexible IC Metrology
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Solution Overview
Problem
Current overlay metrology in IC fabrication uses 2D marks that integrate measurement features for both x and y axes, limiting flexibility and accuracy due to the need for a single set of measurement features for each direction, which compromises performance and reduces the ability to select optimal features for each reticle and layer.
Innovation Solution
Decomposing 2D marks into separate 1D marks for x and y directions allows for independent selection of measurement features, providing multiple options per layer and direction, enhancing measurement flexibility and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If 2D marks are used to integrate measurement features for both x and y axes, then the device complexity is reduced, but the measurement precision deteriorates due to limited feature selection flexibility
Solution Approach 1:
The patent divides the integrated 2D overlay mark into separate 1D overlay marks for x-axis and y-axis measurements. Each 1D mark contains dedicated measurement features optimized for its specific direction, allowing independent selection and optimization of features without compromising the other axis, thereby improving measurement precision while maintaining manageable system complexity
Solution Approach 2:
The patent applies different measurement feature styles and configurations to different directional marks based on their specific measurement requirements. Each 1D mark can be independently optimized with feature styles best suited for its measurement direction, achieving local optimization of measurement quality for each axis
2Device complexity
If a single 2D mark provides one style of measurement feature for each direction, then the device complexity is minimized, but the adaptability deteriorates due to inability to select optimal features for each reticle and layer
Solution Approach 1:
By separating the measurement system into independent 1D marks for x and y directions, the patent enables independent selection of measurement feature styles for each direction and layer combination, providing adaptability without requiring complex integrated designs
Solution Approach 2:
The patent creates a universal framework where multiple measurement feature styles can be applied across different 1D marks and layer combinations. Each 1D mark can utilize different feature styles (e.g., grating, line-space, target patterns) optimized for specific reticle and layer requirements, achieving multi-functionality in feature selection
Data Source
AI summary
Embodiments disclosed herein include semiconductor die with overlay marks, electronic devices that include semiconductor dies with overlay marks, and methods of measuring overlay. In one embodiment, a semiconductor die includes multiple overlay marks, including a first overlay mark and a second overlay mark. The first overlay mark is at a first position on the semiconductor die and includes a first set of patterns with a first orientation. The second overlay mark is at a second position on the semiconductor die and includes a second set of patterns with a second orientation. The first position of the first mark and the second position of the second mark are non-overlapping. In addition, the first orientation of the patterns in the first mark is substantially orthogonal to the second orientation of the patterns in the second mark.