Aperture Combination Optimization for Semiconductor Defect Detection
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Solution Overview
Problem
Current semiconductor wafer inspection systems face challenges in optimizing illumination pupil aperture configurations and modes for effective defect detection, leading to suboptimal signal-to-noise ratios and difficulty in distinguishing between defect of interest and nuisance defects.
Innovation Solution
A method is developed to determine the optimum configuration of illumination and collection apertures by analyzing composite images obtained from various aperture combinations, selecting those that maximize the defect of interest signal-to-noise ratio, and adjusting settings such as wavelength range, focus offset, and polarization states to enhance defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional aperture configurations are used in inspection systems, then the inspection process can be performed, but the signal-to-noise ratio is suboptimal and defect detection sensitivity is reduced
Solution Approach 1:
The patent applies parameter changes by systematically varying aperture configurations (illumination and collection aperture positions, sizes, and shapes) and inspection modes (wavelength range, focus offset, polarization states) to optimize the signal-to-noise ratio for defect detection. The method evaluates multiple parameter combinations and selects the optimal configuration that maximizes defect detection sensitivity while maintaining reliable signal quality.
2Measurement precision
If multiple aperture combinations are tested to optimize defect detection, then detection sensitivity improves, but the complexity of the inspection process increases
Solution Approach 1:
The patent implements preliminary action by pre-determining and storing optimal aperture configurations and inspection modes through systematic evaluation before actual defect inspection. The method creates a database of pre-optimized parameters that can be quickly retrieved and applied to different inspection scenarios, eliminating the need for real-time complex calculations and reducing operational complexity while maintaining high detection sensitivity.
3Ease of operation
If the inspection tool uses fixed aperture settings, then the operation is simple, but the ability to distinguish between defect classes and minimize nuisance events is limited
Solution Approach 1:
The patent applies dynamics by enabling the inspection system to dynamically adjust aperture configurations and inspection modes based on the specific defect characteristics and inspection requirements. The system can switch between different pre-optimized aperture settings and modes to best distinguish between defect classes and minimize nuisance events, while maintaining ease of operation through automated selection based on stored optimization data.
Data Source
AI summary
Disclosed are methods and apparatus for optimizing a mode of an inspection tool. A first image or signal for each of a plurality of first apertures of the inspection tool is obtained, and each first image or signal pertains to a defect area. For each of a plurality of combinations of the first apertures and their first images or signals, a composite image or signal is obtained. Each composite image or signal is analyzed to determine an optimum one of the combinations of the first apertures based on a defect detection characteristic of each composite image. In one aspect, determining an optimum one of the combinations of the first apertures includes selecting a set of one or more individual apertures that result in the highest signal to noise ratio for the defect area, and the method includes setting the optimum combination of the first apertures on the inspection tool and inspecting a sample using such optimum combination of the first apertures.