EUV Mask Defect Management via Pattern Shifting
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Solution Overview
Problem
The challenge in fabricating EUV exposure masks lies in the difficulty of completely eliminating defects on the substrate, which can lead to phase defects and positional deviations during pattern transfer, making it hard to manufacture semiconductor devices using these masks effectively.
Innovation Solution
A method that involves measuring and storing defect position data for EUV exposure mask blanks, shifting the pattern layout to ensure that defects are within the light shielding region, and using charged particle beams to write the pattern on a selected mask blank with minimal defects in the light shielding area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strict inspection and selection of substrates are performed to eliminate defects, then manufacturing precision is improved, but productivity deteriorates due to increased inspection time and substrate rejection
Solution Approach 1:
The patent applies preliminary action by measuring and storing defect position data for multiple mask blanks before the actual pattern writing process. This allows the system to pre-identify suitable substrates and plan pattern placement strategies in advance, rather than performing inspections during or after manufacturing, thereby reducing overall inspection time while maintaining high precision
Solution Approach 2:
The patent changes the parameter of defect management from binary (defect present/absent) to spatial (defect position and pattern placement relationship). By storing defect position data and using it to determine optimal pattern arrangements, the system transforms the inspection process into a data-driven optimization problem that reduces reinspection needs and improves throughput
2Reliability
If pattern layout is shifted to include defects in light shielding region, then reliability is improved by preventing phase defects, but manufacturing precision deteriorates due to additional processing steps
Solution Approach 1:
The patent implements feedback by using measured defect position data to adjust pattern placement decisions. The system continuously references stored defect information during the pattern writing process, dynamically determining whether to shift patterns based on actual defect locations, thereby maintaining high reliability while minimizing unnecessary precision compromises
Solution Approach 2:
The patent applies dynamics by making pattern placement flexible rather than fixed. The system can dynamically adjust pattern positions based on real-time defect data and manufacturing conditions, allowing optimal balance between reliability (hiding defects) and precision (maintaining pattern accuracy) for each specific mask blank
3Reliability
If multiple mask blanks are inspected and stored with defect data, then reliability is improved by enabling defect avoidance, but device complexity increases due to additional storage and management systems
Solution Approach 1:
The patent applies copying by creating digital replicas of defect information through measured defect position data stored in memory. Instead of physically inspecting each mask blank during manufacturing, the system uses copied defect data from preliminary measurements to guide pattern placement, significantly reducing the need for complex real-time inspection hardware while maintaining high reliability
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 the fabrication of EUV exposure masks with reduced defects, preventing phase defects from being transferred to the wafer during pattern printing, thereby improving the precision and reliability of semiconductor device manufacturing.
Implementation Method 1
writing the figure pattern on a searched EUV exposure mask blank such that a number of defects not being located in a light shielding region is less than or equal to the threshold value, using a charged particle beam
Data Source
AI summary
An exposure mask fabrication method includes measuring and storing defect position data, for each EUV exposure mask blank, that indicates the position of at least one defect in each of plural EUV exposure mask blanks, inputting pattern data defining a figure pattern to be written, searching, when the figure pattern is written, in plural EUV exposure mask blanks, an EUV exposure mask blank where the figure pattern can be arranged such that the number of defects not located in a light shielding region is less than or equal to a threshold value, based on the arrangement position of the figure pattern in the pattern data, using the defect position data for each EUV exposure mask blank, and writing the figure pattern on a searched EUV exposure mask blank such that the number of defects not located in the light shielding region is less than or equal to the threshold value.