Dynamic Illumination for Semiconductor Wafer Inspection
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Solution Overview
Problem
Optical inspection tools face challenges in detecting defects in semiconductor objects due to significant differences in light intensity between various areas, leading to detector saturation issues, where high-intensity periphery areas saturate detectors, making it difficult to detect defects in lower-intensity array areas.
Innovation Solution
An optical inspection system dynamically adjusts illumination characteristics, such as intensity, polarization, and spectral band, based on pre-inspection data to ensure appropriate illumination levels for different areas of semiconductor objects, using adjustable optics and attenuators to optimize imaging without saturating detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high illumination intensity is used to detect defects in array areas, then defect detection sensitivity in low-intensity areas is improved, but detector saturation occurs in high-intensity periphery areas
Solution Approach 1:
The patent divides the semiconductor wafer into multiple regions (array area and periphery area) with different illumination requirements. The illumination system is segmented to provide different illumination intensities to different regions simultaneously, allowing optimal defect detection in each region without detector saturation.
Solution Approach 2:
The patent implements local quality by providing different illumination intensities to different areas of the wafer. High-intensity illumination is applied to array areas where defect detection sensitivity is needed, while low-intensity illumination is applied to periphery areas to prevent detector saturation. This localized approach optimizes detection performance for each specific region.
2Ease of operation
If uniform illumination is used across the entire wafer, then inspection process simplicity is maintained, but defect detection quality varies across different areas
Solution Approach 1:
The patent implements dynamic illumination control where the illumination intensity is automatically adjusted based on the detected wafer region. The system transitions from static uniform illumination to dynamic region-specific illumination, maintaining operational simplicity while significantly improving defect detection quality across different wafer areas.
Solution Approach 2:
The patent uses feedback mechanisms where the system detects which region of the wafer is currently being inspected and automatically adjusts the illumination intensity accordingly. This closed-loop control maintains inspection process simplicity while ensuring optimal illumination for each specific region, thereby improving overall defect detection quality.
Data Source
AI summary
An optical inspection system or tool can be configured to inspect objects using dynamic illumination where one or more characteristics of the illumination is/are adjusted to meet the inspection needs of different areas. For example, the illumination intensity may be increased or decreased as the tool inspects areas of memory and periphery features in a wafer die. In some embodiments, the adjustment can be based on data obtained during a pre-inspection setup sequence in which images taken based on illumination with varying characteristics are evaluated for suitability in the remainder of the inspection process.