Apodization Device for Semiconductor Inspection Diffraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor inspection tools face challenges in accurately detecting defects on patterned wafers due to optical artifacts caused by diffraction from apertures, which limit sensitivity and increase noise levels, especially in unpatterned regions.
Innovation Solution
The implementation of a selectable apodization system in the optical pathway of inspection systems, using configurable apodization devices with apodization elements and actuation stages, and serrated aperture assemblies or Fourier filters with edge apodization, to reduce diffraction effects and enhance resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial filters including Fourier filters and apodizing filters are used to enhance patterned wafer inspection, then defect detection capability is improved, but optical artifacts caused by diffraction from apertures increase noise levels and limit sensitivity
Solution Approach 1:
The patent applies apodization functions that modify the amplitude transmission profile of the aperture, changing the parameter of light distribution from uniform to a controlled gradient pattern. This parameter change reduces diffraction effects at aperture edges while maintaining the filtering enhancement capabilities, thereby reducing optical artifacts and noise levels in unpatterned regions.
Solution Approach 2:
The patent implements different apodization profiles for different regions of the aperture, with stronger apodization at the edges and weaker or no apodization in the center. This local differentiation allows the system to reduce diffraction artifacts where they occur most (at aperture boundaries) while preserving light collection efficiency and defect detection capability in the central region.
2Use of energy by moving object
If traditional aperture designs are used to maintain high light collection efficiency, then signal strength is improved, but diffraction effects increase optical artifacts and reduce resolution
Solution Approach 1:
The patent transforms the aperture transmission parameter from a uniform distribution to a controlled apodized distribution. This parameter change enables the system to achieve both high light collection efficiency (by maintaining substantial overall transmission) and reduced diffraction effects (by controlling the amplitude profile at aperture boundaries), thereby simultaneously improving signal strength and resolution.
3Manufacturing precision
If apodization is applied to reduce diffraction effects, then resolution and sensitivity are improved, but light collection efficiency may be reduced
Solution Approach 1:
The patent applies apodization selectively at the aperture edges where diffraction effects are most problematic, rather than uniformly across the entire aperture. This localized approach reduces diffraction artifacts and improves resolution while minimizing the impact on overall light collection efficiency, as the central region maintains higher transmission.
Solution Approach 2:
The patent implements partial apodization, applying the apodization function only to the extent necessary to reduce diffraction effects to acceptable levels. By using moderate apodization profiles rather than extreme ones, the system achieves sufficient artifact reduction while preserving adequate light collection efficiency for sensitive defect detection.
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 allows for improved defect detection sensitivity by minimizing optical artifacts and increasing resolution, particularly in regions with bright peripheral structures, while maintaining high light collection efficiency.
Implementation Method 1
optical artifacts caused by diffraction from apertures
Implementation Method 2
selectable apodization system in the optical pathway of inspection systems, using configurable apodization devices with apodization elements
Implementation Method 3
an illumination source configured to illuminate a surface of a sample disposed on a sample stage. In another embodiment, the inspection system includes a detector configured to detect at least a portion of light emanating from the surface of the sample, the illumination source and the detector being optically coupled via an optical pathway
Data Source
AI summary
An inspection system with selectable apodization includes a selectably configurable apodization device disposed along an optical pathway of an optical system. The apodization device includes one or more apodization elements operatively coupled to one or more actuation stages. The one or more actuation stages are configured to selectably actuate the one or more apodization elements along one or more directions. The inspection system includes a control system communicatively coupled to the one or more actuation stages. The control system is configured to selectably control an actuation state of at the one or more apodization elements so as to apply a selected apodization profile formed with the one or more apodization elements.