Interferometer Pixel Subsetting for Wafer Warp Inspection Throughput
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Solution Overview
Problem
Interferometer systems in semiconductor fabrication face a decrease in throughput due to the need for smaller sensor pixels to measure high-warp samples, which increases computational costs and data processing complexity.
Innovation Solution
An inspection system that processes only a subset of pixels from the phase map for phase unwrapping operations, allowing for improved data processing efficiency and increased throughput by performing the most computationally expensive operations on a selected subset of pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If smaller sensor pixel sizes are used to achieve larger single-shot sample measurement coverage on high-warp samples, then measurement coverage is improved, but computational costs increase significantly and throughput decreases
Solution Approach 1:
The patent segments the sensor array into multiple zones with different pixel sizes. Central pixels have smaller sizes for high-resolution measurement of critical sample areas, while peripheral pixels have larger sizes for capturing broader sample coverage. This segmentation allows the system to achieve both large measurement coverage and acceptable throughput by processing fewer high-resolution pixels.
2Measurement precision
If smaller sensor pixel sizes are used to resolve dense fringes from sample areas with high surface slope, then measurement precision is improved, but computational costs increase significantly
Solution Approach 1:
The patent applies local quality by assigning different pixel sizes to different spatial locations. Central pixels are made smaller to achieve high fringe resolution for precise measurement of critical sample regions, while peripheral pixels are larger to reduce computational burden. This local differentiation allows the system to maintain high measurement precision where needed without incurring computational costs across the entire array.
3Area of stationary object
If larger numbers of sensor pixels are processed to achieve larger single-shot sample measurement coverage, then measurement coverage is improved, but data processing complexity increases
Solution Approach 1:
The patent segments the sensor array into central and peripheral zones with different pixel sizes. This segmentation reduces the total number of pixels requiring high-resolution processing while maintaining large sample coverage capability. The smaller central pixel array handles critical measurements with high precision, while the larger peripheral pixels capture broader sample areas with reduced processing requirements.
Solution Approach 2:
The patent applies local quality by differentiating pixel sizes across spatial locations. Peripheral pixels are larger and require less computational processing, while central pixels are smaller and handle precision-critical data. This local differentiation reduces overall data processing complexity while maintaining comprehensive sample coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-resolution surface height maps while maintaining high throughput, avoiding the need to process every pixel simultaneously and reducing the computational burden.
Implementation Method 1
Metrology methods based on interferometry have been used in the art of semiconductor fabrication in order to measure certain characteristics samples, including surface height and surface slope
Data Source
AI summary
An inspection system is disclosed. In one embodiment, the inspection system includes an interferometer sub-system configured to acquire an interferogram of a sample. The inspection system may further include a controller communicatively coupled to the interferometer sub-system. The controller is configured to: receive the interferogram from the interferometer sub-system; generate a phase map of the sample based on the received interferogram, wherein the phase map includes a plurality of pixels; select a sub-set of pixels of the plurality of pixels of the phase map to be used for phase unwrapping procedures; perform one or more phase unwrapping procedures on the sub-set of pixels of the phase map to generate an unwrapped phase map; and generate a surface height map of the sample based on the unwrapped phase map.