Optical Testing Device for Metasurface Critical Dimension Metrology
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Solution Overview
Problem
Standard metrology techniques, such as relying on a single critical dimension mesdim, are inadequate for ensuring the full range of critical dimensions in metasurface-based optical systems, failing to account for etch density effects and leading to potential manufacturing errors.
Innovation Solution
A testing device with a substrate and pillars of varying diameters and shapes, representative of the range of critical dimensions, is used to guarantee accurate critical dimension measurement, incorporating etch density effects through a dedicated mesdim structure with a range of polygon shapes, ensuring continuity of critical dimensions in the final product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single critical dimension mesdim is used for metrology, then the measurement process is simple, but it cannot guarantee that the full range of critical dimensions in the metasurface are within specification
Solution Approach 1:
The patent divides the metrology structure into multiple segmented mesdims, each representing different critical dimension ranges (first mesdim for smaller dimensions, second mesdim for larger dimensions). This segmentation allows comprehensive coverage of the full critical dimension spectrum while maintaining manageable complexity in each individual mesdim structure.
Solution Approach 2:
The patent introduces a new dimension of metrology by creating multiple mesdims with different spatial arrangements and critical dimension ranges. Instead of relying on a single mesdim, the solution adds dimensional diversity through multiple mesdims that collectively cover the entire critical dimension spectrum of the metasurface.
2Manufacturing precision
If different regular critical dimension mesdims are used to cover the full range, then the critical dimension coverage is improved, but catching the etch density effect is not guaranteed due to random spatial repartition
Solution Approach 1:
The patent applies local quality by designing mesdims with specific spatial arrangements tailored to detect particular manufacturing effects. The first mesdim uses a regular spatial pattern optimized for detecting etch density effects, while the second mesdim uses a different arrangement for verifying critical dimensions. Each mesdim is locally optimized for its specific detection function.
Solution Approach 2:
The patent implements feedback mechanisms by measuring critical dimensions in multiple mesdims and comparing results against specification targets. The measurement data from different mesdims provides feedback on both etch density effects and overall critical dimension compliance, enabling process adjustment and verification.
Data Source
AI summary
A device for testing an optical device, comprising a first structure comprising a substrate made of a first material and at least two first pillars of cylindrical shape made of a second material crossing the substrate, the second material having an optical index different from the optical index of the first material.