Wafer Defect Inspection via Pattern Density Sensitivity Ranking
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Solution Overview
Problem
In semiconductor device manufacturing, defect inspections in logic products with random patterns face challenges due to scattered high-sensitivity and low-sensitivity regions, leading to difficulties in manually setting sensitivities and resulting in undetected defects in low-sensitivity areas, as existing methods based solely on line density do not accurately reflect defect detection sensitivity and are cumbersome to implement.
Innovation Solution
A defect inspecting apparatus that divides the inspection region into subregions, calculates pattern density based on design data, assigns sensitivity ranks to inspection execution regions, and sets inspection parameters to effectively detect defects, allowing for automated parameter setting and improved defect detection across varying sensitivity regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the same sensitivity level is used for the entire wafer, then the inspection process is simple and fast, but defects in low-sensitivity regions cannot be detected
Solution Approach 1:
The patent applies local quality by dividing the wafer into multiple inspection regions with different sensitivity levels. Each region is assigned a sensitivity rank (first sensitivity level or second sensitivity level) based on its specific characteristics, allowing defects to be detected with appropriate sensitivity in each local area rather than using a uniform sensitivity across the entire wafer.
Solution Approach 2:
The patent segments the inspection region into multiple subregions, each with distinct sensitivity characteristics. This segmentation allows the inspection system to handle different regions with different sensitivity levels, resolving the contradiction between detection precision and operational simplicity.
2Measurement precision
If manual sensitivity setting is performed for each region, then defect detection accuracy improves, but the inspection process becomes time-consuming and complex
Solution Approach 1:
The patent implements self-service by automatically determining sensitivity ranks for different inspection regions based on pre-stored region characteristics. The system autonomously assigns sensitivity levels without requiring manual operator intervention, thereby maintaining high defect detection accuracy while significantly reducing operational complexity and time consumption.
Solution Approach 2:
The patent applies preliminary action by pre-storing characteristics of inspection regions and pre-determining sensitivity ranks before the actual inspection process. This preliminary preparation allows the system to automatically configure inspection parameters without manual intervention during the inspection process.
3Measurement precision
If sensitivity is increased to detect defects in low-sensitivity regions, then defect detection capability improves, but false defect rate increases
Solution Approach 1:
The patent applies local quality by assigning different sensitivity levels to different regions based on their specific characteristics. High-sensitivity regions receive the first sensitivity level for detecting subtle defects, while low-sensitivity regions receive the second sensitivity level to minimize false defects. This localized approach resolves the contradiction between detection capability and false defect rate.
Solution Approach 2:
The patent changes the sensitivity parameter dynamically based on the inspection region. By selecting different sensitivity levels (first and second sensitivity levels) according to the region's characteristics, the system optimizes the balance between detecting real defects and reducing false defects in each local area.
4Measurement precision
If the inspection region is divided into many subregions with different sensitivity ranks, then defect detection accuracy improves, but the number of inspection execution regions becomes enormous and difficult to manage
Solution Approach 1:
The patent merges subregions with the same sensitivity rank into larger inspection execution regions. This consolidation reduces the total number of execution regions while maintaining the benefit of differentiated sensitivity levels. Regions with identical sensitivity characteristics are combined into unified execution regions, making the system more manageable.
Solution Approach 2:
The patent maintains local quality by preserving distinct sensitivity levels for different regions while merging regions with identical sensitivity characteristics. This approach reduces the number of execution regions through merging while still providing region-specific sensitivity optimization where needed.
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 enables accurate defect detection in both high and low-sensitivity regions, reduces false defect rates, and automates the setting of inspection parameters, thereby enhancing the efficiency and effectiveness of the defect inspection process.
Implementation Method 1
A defect inspection is performed by illuminating a wafer with inspection light, collecting reflected light with a lens
Data Source
AI summary
A defect inspecting apparatus comprising:an inspection region dividing section which divides a defect inspection region of a wafer on which a circuit pattern is formed into a plurality of inspection subregions;a pattern density calculating section which calculates the pattern density of each of the inspection subregions on the basis of design data of the circuit pattern;an inspection execution region and sensitivity rank setting section which assigns a sensitivity rank based on the pattern density to a plurality of inspection execution regions, each including a plurality of the inspection subregions; anda defect inspecting section which sets an inspection parameter on the basis of sensitivity ranks of the inspection execution regions and inspects the inspection execution regions for a defect.