Multi-Waveband Wafer Inspection for Defect Alignment and Sensitivity
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Solution Overview
Problem
Current optical inspection methods for semiconductor wafers require multiple inspections using different wavebands, which can lead to misalignments and reduced defect detection sensitivity, especially for defects buried under the surface or with varying optical properties.
Innovation Solution
A method and apparatus that simultaneously illuminate semiconductor wafers with light in multiple wavebands, allowing for independent conditioning of each waveband's intensity, polarization, and beam spot, enabling targeted defect detection by leveraging the strengths of each waveband and improving defect classification and detection in both surface and subsurface layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple inspections are performed using different wavebands, then defect detection sensitivity is improved, but misalignments occur and inspection time increases
Solution Approach 1:
The patent combines multiple waveband inspections into a single simultaneous inspection process. The illumination system emits multiple wavebands (e.g., UV, visible, IR) at the same time, and the detection system captures images from all wavebands in one pass, eliminating the need for sequential inspections and preventing misalignments between different waveband images.
Solution Approach 2:
The patent adds the waveband dimension to the inspection process by simultaneously utilizing multiple wavelength ranges. Instead of performing separate inspections in different time dimensions, the system inspects across the spectral dimension concurrently, achieving both improved detection sensitivity and reduced inspection time.
2Measurement precision
If multiple inspections are performed using different wavebands, then defect detection sensitivity is improved, but misalignments occur between inspections
Solution Approach 1:
The patent merges multiple waveband inspections into a single simultaneous operation. By illuminating the semiconductor wafer with multiple wavebands at the same time and capturing images from all wavebands in one pass, the system eliminates positional drift and alignment errors that occur during sequential inspections.
Solution Approach 2:
The system performs preliminary alignment using reference marks visible across multiple wavebands before actual defect inspection. This preliminary positioning ensures that all subsequent multi-waveband images are captured from the exact same location, preventing misalignments.
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 enhances defect detection and classification by utilizing the relative strengths of different wavebands in a single inspection, reducing misalignments and improving sensitivity to various defect types, including those buried under the surface, while maintaining throughput and reducing noise.
Implementation Method 1
illuminates the semiconductor wafer with light having wavelengths in multiple wavebands
Implementation Method 2
different wavebands may be relatively better or worse for detecting various different defect types
Data Source
AI summary
A method of qualifying semiconductor wafer processing includes: illuminating a semiconductor wafer simultaneously with source light having wavelengths in a plurality of wavebands, including at least a first waveband and a second waveband, the second waveband being different from the first waveband; separating light reflected from the semiconductor wafer as a result of said illuminating, the separating dividing the reflected light according to waveband; generating a first image of the semiconductor wafer based on reflected light separated into the first waveband; and, generating a second image of the semiconductor wafer base on reflected light separated into the second waveband.