Wafer Metrology Resolution via Sub-Pixel Modulation
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Solution Overview
Problem
Interferometer wafer metrology systems face limitations in resolving patterned wafer surfaces, leading to inaccuracies in geometry measurements, which hinder effective monitoring and design improvements in wafer manufacturing.
Innovation Solution
The method involves acquiring multiple wafer geometry images with different sub-pixel modulations in spatial phase and processing them using statistical treatments to produce resolution-enhanced representations, enabling ultra-high resolution topography measurements and pattern layout optimizations through dummy-fill insertion in regions with high frequency variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometer wafer metrology systems are used to scan wafer surfaces, then complete data sets for topography and geometry monitoring are obtained, but the imaging device resolution cannot fully resolve certain patterned wafer surfaces, limiting measurement accuracy
Solution Approach 1:
The imaging process is segmented into multiple acquisitions with different sub-pixel modulations. Instead of attempting to capture all detail in a single image, the system divides the measurement into multiple phases, each capturing a different aspect of the sub-pixel information. This segmentation allows the final reconstructed image to exceed the nominal resolution of individual imaging devices.
Solution Approach 2:
The patent adds a temporal dimension to the imaging process by acquiring multiple images over time with different sub-pixel modulations. This transforms a two-dimensional spatial resolution problem into a three-dimensional problem involving time-series data, allowing statistical processing to extract sub-pixel information that cannot be obtained from static single-frame images.
2Measurement precision
If multiple wafer geometry images with sub-pixel modulation are acquired and jointly processed, then resolution-enhanced representations are produced, but measurement and processing time increases
Solution Approach 1:
The system performs preliminary actions by acquiring multiple images with different sub-pixel modulations before final processing. This preparatory data collection enables the statistical processing algorithm to work with pre-organized multi-phase data, reducing the computational burden during actual measurement and allowing real-time or near-real-time resolution enhancement.
Solution Approach 2:
The joint processing of multiple images provides feedback information about sub-pixel variations that is used to refine the resolution-enhanced representation. This feedback mechanism allows the system to iteratively improve measurement accuracy by utilizing information from all acquired images, ensuring that the final result maximizes the available data while minimizing processing redundancy.
Data Source
AI summary
Methods and systems enabling ultra-high resolution topography measurements of patterned wafers are disclosed. Measurements obtained utilizing the ultra-high resolution metrology may be utilized to improve wafer metrology measurement accuracies. Additionally, measurements obtained utilizing the ultra-high resolution metrology may also be utilized to provide feedback and/or calibration control to improve fabrication and design of wafers.