Wafer Inspection Camera Tuning for Accurate 3D Feature Reconstruction
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Solution Overview
Problem
Conventional wafer inspection systems (WIS) struggle with suboptimal 3D reconstruction of features on semiconductor substrates due to inadequate image capture and lack of dynamic adjustment of camera parameters, leading to incomplete or inaccurate reconstructions.
Innovation Solution
The system and method automatically adjust camera parameters such as illumination intensity, off-axis illumination shape, and focus height to optimize image capture, filter images for quality, and determine when sufficient images are obtained for accurate 3D reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional WIS modules use predetermined camera settings to capture images at fixed locations, then the inspection process is simple and fast, but the 3D reconstruction accuracy is insufficient
Solution Approach 1:
The patent implements dynamic adjustment of camera parameters (illumination intensity, off-axis illumination shape, focus height) based on real-time analysis of captured images. The system transitions from static predetermined settings to dynamic adaptive settings, allowing the camera system to optimize its parameters during the inspection process to improve 3D reconstruction accuracy
Solution Approach 2:
The system analyzes captured images to determine whether camera parameters should be adjusted, creating a feedback loop. The analysis unit evaluates image quality and provides feedback to the control unit, which then adjusts parameters accordingly. This closed-loop control ensures optimal parameters are used for accurate 3D reconstruction while maintaining operational simplicity
2Measurement precision
If the camera system captures a fixed number of images at predetermined locations, then the throughput is high, but the image quality may be inadequate for accurate reconstruction
Solution Approach 1:
The system captures images and analyzes them to determine if additional images are needed. Rather than always capturing a fixed predetermined number of images, the system performs partial action (capturing only the necessary number of high-quality images needed for accurate reconstruction), thereby maintaining throughput while ensuring image quality
Solution Approach 2:
The number of images captured is made dynamic rather than fixed. The system adjusts the number of images captured based on real-time analysis of image quality and reconstruction needs, allowing flexibility to optimize both throughput and reconstruction accuracy for different features and conditions
3Measurement precision
If camera parameters are manually adjusted for each inspection, then the reconstruction accuracy improves, but the operation time increases
Solution Approach 1:
The camera system performs self-adjustment of parameters through automated analysis and control. The system analyzes its own captured images and automatically adjusts its parameters without requiring manual intervention, thereby maintaining high accuracy while minimizing time loss. The control unit executes parameter adjustments autonomously based on image analysis results
Solution Approach 2:
The automated feedback mechanism eliminates manual parameter adjustment time. The system continuously analyzes image quality and provides real-time feedback for parameter optimization, replacing time-consuming manual adjustments with rapid automated feedback loops that maintain accuracy while reducing operational time
Data Source
AI summary
Embodiments of systems and methods are disclosed for inspecting features formed within and/or on a semiconductor substrate. More specifically, the present disclosure provides various embodiments of systems and methods to automatically adjust one or more parameters (or camera settings) used by a camera system to capture a stack of images of a feature formed within and/or on a semiconductor substrate before the images are processed to generate a three-dimensional (3D) reconstruction of the feature. In some embodiments, the disclosed systems and methods may filter the images included within the stack of images used for 3D reconstruction and dynamically determine when the camera system has captured enough images for 3D reconstruction of the feature. In doing so, the disclosed systems and methods may provide a more complete and accurate 3D reconstruction of the feature, while improving throughput of the wafer inspection process.