Simultaneous multi-bandwidth optical inspection of semiconductor devices
Find Innovative SolutionsGenerate Solutions
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 using different wavebands are performed sequentially, then defect detection sensitivity is improved, but misalignment between inspections occurs and productivity decreases
Solution Approach 1:
The patent combines multiple waveband inspections into a single simultaneous operation using a multi-bandwidth optical inspection system. The system illuminates the semiconductor wafer with multiple wavebands at the same time and captures images from each waveband through separate detection channels, eliminating the need for sequential inspections and preventing misalignment while maintaining high defect detection sensitivity.
Solution Approach 2:
The patent introduces a spectral dimension by utilizing multiple wavebands simultaneously rather than sequentially. By adding the wavelength dimension to the inspection process and processing each waveband through independent detection channels, the system achieves both high measurement precision and productivity without the misalignment problems of sequential methods.
2Measurement precision
If multiple inspections using different wavebands are performed sequentially, then defect detection sensitivity is improved, but misalignment between inspections occurs
Solution Approach 1:
The patent merges multiple waveband inspections into a single simultaneous operation where all wavebands illuminate the wafer at the same time and are captured through co-aligned optical channels. This eliminates the temporal separation that causes misalignment in sequential inspections, ensuring that defects are detected with both high sensitivity and precise spatial accuracy.
3Productivity
If single waveband inspection is used, then productivity is maintained, but defect detection sensitivity decreases especially for subsurface defects
Solution Approach 1:
The patent combines the advantages of single-waveband simplicity with multi-waveband sensitivity by simultaneously illuminating the wafer with multiple wavebands and processing each through independent detection channels. This maintains the high throughput of single-waveband inspection while achieving the enhanced defect detection sensitivity of multi-waveband systems, particularly for subsurface defects.
4Measurement precision
If multiple wavebands are used with independent conditioning, then defect classification accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the optical detection system into multiple independent channels, each dedicated to a specific waveband. Each channel has its own detection sensor and can independently condition and process the light from its assigned waveband. This segmentation allows for sophisticated defect classification using multiple wavebands while organizing the complexity into manageable, modular units.
Solution Approach 2:
The patent creates a multi-functional inspection system where each detection channel can handle multiple functions: detecting defects in its assigned waveband, classifying defect types based on waveband-specific optical properties, and providing independent image processing. This universality allows the system to achieve high defect classification accuracy while reusing similar hardware components across multiple wavebands.
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 misregistration and improving sensitivity to various defect types, including those buried under the surface, while maintaining alignment and reducing surface noise.
Implementation Method 1
separating light reflected from the semiconductor wafer as a result of illuminating the semiconductor wafer
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.