Photomask Diffraction Parameter Retrieval for Wafer Defect Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining whether defects on a photomask are printed on a wafer during semiconductor production are inefficient and costly, as they require capturing and analyzing multiple images to optimize diffraction parameters, leading to high computational burdens.
Innovation Solution
A method and system for optimizing diffraction parameters using a reduced number of captured images by iteratively updating a rasterized photomask image based on similarity comparisons between digital microscope simulation images and actual images, employing Fourier Transform-related formulas and TCC eigenfunctions to minimize loss functions, and generating scanner simulation images for defect determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images are captured and analyzed to optimize diffraction parameters, then measurement precision is improved, but computational burden and time consumption increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing diffraction parameters for various photomask designs before actual defect detection is needed. This allows rapid retrieval of optimized parameters without performing time-consuming computational optimization during the defect detection process, thus maintaining measurement precision while reducing real-time computational time.
Solution Approach 2:
The patent creates a database of pre-optimized diffraction parameters that serves as a copy or reference model. Instead of performing complex computational optimization on each actual photomask image, the system retrieves and applies pre-computed parameter sets that match the photomask design, significantly reducing computational burden while maintaining accuracy.
2Measurement precision
If multiple images are captured and analyzed to optimize diffraction parameters, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex computational optimization process from the actual defect detection system. By separating the diffraction parameter optimization into a pre-processing stage and storing only the essential parameter values in a database, the system removes the complexity of real-time computational optimization while maintaining measurement precision through retrieved pre-optimized parameters.
3Loss of energy
If a reduced number of captured images is used, then computational costs are reduced, but diffraction parameter optimization accuracy may deteriorate
Solution Approach 1:
The patent performs the image capture and analysis in advance during photomask fabrication or quality control, not during defect detection. By pre-optimizing diffraction parameters using a comprehensive set of images at the appropriate time, the system achieves accurate parameter optimization without incurring high computational costs during the subsequent defect detection process.
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 efficiently and accurately determines whether defects on the photomask will be printed on the wafer, reducing computational costs and improving the precision of defect detection, thereby optimizing photomask fabrication processes.
Implementation Method 1
retrieve at least one diffraction parameter of the photomask based on the rasterized photomask image
Implementation Method 2
generating a digital microscope simulation image based on the at least one diffraction parameter
Data Source
AI summary
The present disclosure provides a method and a system for retrieving diffraction parameter of a photomask. The method includes: determining at least one first diffraction parameter of a first rasterized photomask image corresponding to a photomask; determining a digital microscope simulation image according to the at least one first diffraction parameter; comparing the digital microscope simulation image with a captured image to generate a difference image, wherein the captured image is generate by an image capture device equipped with the photomask; determining a second rasterized photomask image according to the first rasterized photomask image, the difference image and the at least one first diffraction parameter; and determining at least one second diffraction parameter of the second rasterized photomask image.