Defect Estimation Device for Mask Inspection Accuracy
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Solution Overview
Problem
Current mask inspection technologies face challenges in accurately detecting and evaluating defects, particularly in miniaturized patterns, as they struggle to distinguish between shape defects and errors, and cannot effectively predict the influence of defects on wafer images or determine the necessary repairs to achieve acceptable transfer images.
Innovation Solution
A defect estimation device and method that obtains optical and reference images of mask patterns, compares them to determine defects, and simulates repairs to estimate the impact on wafer images, allowing for the identification of defective areas and the assessment of repair effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If die-to-die inspection method is used to compare identical patterns on the mask, then inspection accuracy is improved, but the ability to detect common defects is lost
Solution Approach 1:
The patent merges die-to-die inspection (comparing identical patterns on the mask) with die-to-database inspection (comparing patterns with design data) methods. The system performs both types of comparisons: comparing measured pattern data with design pattern data to detect all defects, and comparing identical chip patterns or pattern segments with each other to maintain high inspection accuracy while detecting common defects.
2Measurement precision
If die-to-database inspection method is used to compare with design pattern data, then exact pattern comparison is achieved, but system size increases
Solution Approach 1:
The patent segments the inspection system into distinct functional modules: a measurement unit for capturing optical images of patterns, a data processing unit for comparing measured data with design pattern data, and a defect determination unit for identifying defects. This modular segmentation allows the system to perform exact pattern comparison while managing system complexity through organized functional divisions.
3Productivity
If mask pattern dimension is miniaturized to increase LSI capacity, then integration level is improved, but inspection accuracy requirement increases
Solution Approach 1:
The patent replaces traditional mechanical/optical inspection methods with automated electronic measurement and data processing systems. The system uses optical measurement units to capture pattern images, converts them to digital measured pattern data, and employs computer-based algorithms to compare with design data and determine defects. This substitution enables high-precision inspection of miniaturized patterns that would be impossible with conventional mechanical measurement methods.
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 solution enables precise defect detection and evaluation, facilitating accurate determination of necessary repairs and improving the yield of masks by predicting the influence of defects on wafer images, thus reducing manufacturing costs and increasing the quality of pattern transfer.
Implementation Method 1
light transmitted through or reflected from the mask reaches an image sensor, thereby forming an image thereon
Implementation Method 2
light transmitted through or reflected from the mask reaches an image sensor, thereby forming an image thereon
Data Source
AI summary
Acquired mask data of a defect portion is sent to a simulated repair circuit 300 to be simulated. The simulation of the acquired mask data 204 is returned to the mask inspection results 205 and thereafter sent to a wafer transfer simulator 400 along with a reference image at the corresponding portion. A wafer transfer image estimated by the wafer transfer simulator 400 is sent to a comparing circuit 301. When it is determined that there is a defect in the comparing circuit 301, the coordinates and the wafer transfer image which is a basis for the defect determination are stored as transfer image inspection results 206. The mask inspection results 205 and the transfer image inspection result 206 are then sent to the review device 500.