Lithographic Mask Inspection Using Printable Feature Detection
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Solution Overview
Problem
The existing lithographic mask inspection processes are inefficient in distinguishing between printable and non-printable features, leading to high costs and the need for rapid, accurate methods to identify defects.
Innovation Solution
A system and method that assign different inspection process parameters to lithographic mask areas based on the presence of printable features, using a search module to identify features and a decision module to apply specific sensitivity parameters, with thresholds for intensity to differentiate between feature types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rigorous inspection of lithographic masks is performed to detect all defects, then manufacturing precision is improved, but inspection time increases
Solution Approach 1:
The patent applies local quality by assigning different inspection process parameters to different regions of the lithographic mask based on whether they contain printable features. Areas with printable features use first inspection parameters (higher sensitivity), while areas without printable features use second inspection parameters (lower sensitivity or faster inspection), thereby optimizing the balance between defect detection accuracy and inspection time.
Solution Approach 2:
The patent changes inspection parameters dynamically based on the presence of printable features. The system identifies printable features in the expected image and adjusts inspection parameters (such as sensitivity thresholds, inspection depth, or resource allocation) accordingly, allowing rigorous inspection only where necessary while reducing inspection effort in non-critical areas.
2Measurement precision
If high sensitivity inspection parameters are applied to all mask areas, then defect detection accuracy is improved, but false alarm rate increases
Solution Approach 1:
The patent reduces false alarms by applying high sensitivity inspection parameters only to mask areas containing printable features, while using lower sensitivity parameters in areas without printable features. This localized approach ensures that stringent inspection criteria are applied only where defects would impact manufacturing, eliminating unnecessary false alarms in non-critical regions.
Solution Approach 2:
The system performs preliminary identification of printable features in the expected image before conducting the actual inspection. By pre-mapping which areas require high-sensitivity inspection, the system avoids applying high sensitivity parameters universally, thereby preventing false alarms while maintaining detection accuracy in critical areas.
3Ease of operation
If uniform inspection parameters are used across the entire mask, then ease of operation is improved, but inspection efficiency decreases
Solution Approach 1:
The patent improves inspection efficiency by automatically assigning different inspection parameters to different mask regions based on printable feature presence. The system handles the complexity of parameter differentiation automatically, maintaining ease of operation for the user while achieving higher productivity through optimized, location-specific inspection strategies.
Solution Approach 2:
The inspection system performs self-service by automatically identifying printable features and selecting appropriate inspection parameters for each region without requiring manual intervention. The system generates the expected image, identifies printable features, and configures inspection parameters autonomously, thereby improving efficiency while keeping the operation simple for the user.
Data Source
AI summary
According to an embodiment of the invention there may be provided a system for assigning lithographic mask inspection process parameters. The system may include a search module, a decision module and a memory module. The memory module may be configured to store an expected image expected to be formed on a photoresist during a lithographic process that involves illuminating the lithographic mask. The search module may be configured to search in the expected image for printable features. The decision module may be configured to assign a first lithographic mask inspection process parameter to lithographic mask areas related to printable features and assign a second lithographic mask inspection process parameter to at least some lithographic mask areas that are not associated with printable features. The second lithographic mask inspection process parameter may differ from the first lithographic mask inspection process parameter.