Photomask Pattern Inspection Using Dual Exposure Simulation
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Solution Overview
Problem
Existing photomask pattern inspection methods are inefficient and prone to errors due to variations in optical system devices and exposure environments, which can lead to inaccuracies in display device manufacturing.
Innovation Solution
A method and system that utilize first and second exposure simulations based on photomask design and optical image data to generate differential images, defining a photomask as defective or normal based on threshold values, ensuring rapid and accurate inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photomask pattern inspection methods are used, then inspection can be performed, but inspection accuracy deteriorates due to variations in optical system devices and exposure environments
Solution Approach 1:
The patent creates a virtual copy of the photomask pattern through exposure simulation, generating simulated aerial image data that replicates the expected pattern without physical inspection. This virtual model serves as a reference to compare against actual inspection images, eliminating the need for physical photomask inspection while maintaining accuracy.
Solution Approach 2:
The patent transforms the inspection approach by changing parameters from direct physical measurement to simulated optical parameter comparison. By adjusting exposure conditions, wavelength, and numerical aperture in simulations to match actual exposure processes, the system achieves environment-independent inspection accuracy.
2Productivity
If conventional inspection methods are used, then inspection can be performed, but inspection efficiency is low and error-prone
Solution Approach 1:
The patent replaces the mechanical/optical inspection system with a computational simulation system. Instead of using physical optical devices to inspect photomasks, the system uses exposure simulation software to generate and compare aerial images, eliminating mechanical inspection limitations and improving both efficiency and reliability.
Solution Approach 2:
The patent performs exposure simulation in advance to generate expected aerial image data before actual photomask inspection or manufacturing. This preliminary virtual inspection allows for pattern verification and optimization before committing to physical processes, improving overall efficiency and reducing errors.
Data Source
AI summary
A photomask pattern inspection method includes generating first result image data by performing first exposure simulation based on photomask design data, generating second result image data by performing second exposure simulation based on optical image data obtained by photographing an actual photomask, and generating inspection data for the actual photomask based on the first result image data and the second result image data.