Defect Inspection Polarization Control for Sub-Wavelength Sensitivity
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Solution Overview
Problem
Current defect inspection methods struggle to detect minute defects and foreign matters on semiconductor wafers with sizes equal to or smaller than several ten nanometers due to weak reflected, diffracted, and scattered light, especially in sub-wavelength structures, where signal detection sensitivity is low.
Innovation Solution
A defect inspecting apparatus and method that adjusts the polarization state of illumination light and scattered light using polarization generation and analysis parts to enhance detection sensitivity, suppressing scattered light from repeat patterns and improving detection of minute defects in dark-field inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dark-field inspection is used to detect scattered light from minute defects, then detection sensitivity for defects is improved, but scattered light from repeat patterns creates interference and reduces detection accuracy
Solution Approach 1:
The patent changes the polarization state parameter of illumination light and scattered light to resolve the interference between defect signals and repeat pattern signals. By adjusting polarization angles and states, the system enhances the polarization difference between defects and repeat patterns, enabling effective separation of signals and improvement of detection accuracy.
2Measurement precision
If polarization state adjustment is implemented to suppress repeat pattern scattered light, then detection accuracy for minute defects is improved, but device complexity increases due to additional polarization control components
Solution Approach 1:
The patent makes the polarization control components serve multiple functions: they simultaneously control the polarization state of illumination light and the polarization state of scattered light. This multi-functionality reduces the need for separate polarization control components for each function, thereby managing device complexity while achieving high detection accuracy.
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
The solution provides improved detection sensitivity for minute defects, enabling effective inspection of semiconductor wafers by optimizing polarization states for illumination and detection, thereby enhancing the ability to detect defects on sub-wavelength structures.
Implementation Method 1
a polarization generation part to adjust polarization state of the illumination light emitted from the light source
Implementation Method 2
a polarization analysis part to adjust polarization state of scattered light from a sample irradiated by the irradiation optical system
Implementation Method 3
detects light scattered from the surface of the object to be inspected
Data Source
AI summary
A defect inspecting apparatus includes an irradiation optical system having a light source that emits illumination light and a polarization generation part that adjusts polarization state of the illumination light emitted from the light source, a detection optical system having a polarization analysis part that adjusts polarization state of scattered light from a sample irradiated by the irradiation optical system and a detection part that detects the scattered light adjusted by the polarization analysis part, and a signal processing system that processes the scattered light detected by the detection optical system to detect a defect presenting in the sample. The polarization generation part adjusts the polarization state of the illumination light emitted from the light source on the basis of predetermined illumination conditions and the polarization analysis part adjusts the polarization state of the illumination light emitted from the light source on the basis of predetermined detection conditions.