Wafer Pattern Edge Detection Correction Line Generation
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Solution Overview
Problem
The challenge lies in accurately detecting the edge of a wafer pattern deviated from a reference pattern due to manufacturing processes like photolithography and dry etching, leading to misalignment and erroneous defect detection, which existing methods struggle to address effectively.
Innovation Solution
A method and apparatus that generate a correction line by creating an appearance-frequency graph of space widths adjacent to reference patterns, obtaining images of wafer patterns, calculating deviations, and plotting data points on a coordinate system to update the correction line, enabling accurate edge detection and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If the search range for pattern edge is expanded uniformly, then the detection range is improved, but erroneous detection of adjacent pattern edges occurs and reliability deteriorates
Solution Approach 1:
The patent applies local quality by setting different search range expansion amounts for different regions. Specifically, the search range is expanded more in regions with large deviations (determined by the correction line) and less in regions with small deviations, allowing accurate edge detection without causing erroneous detection of adjacent pattern edges.
2Measurement precision
If a complex algorithm is used to accurately detect all edges including those with large deviations, then measurement precision is improved, but computational cost increases and productivity deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating a correction line that represents the deviation trend between reference pattern and wafer pattern edges. This correction line is used to determine region-specific search range expansion amounts before actual edge detection, avoiding the need for complex real-time algorithms during production inspection.
Solution Approach 2:
The patent changes the parameter of search range expansion amount based on the correction line data. Instead of using a fixed or uniformly expanded search range, the system dynamically adjusts the expansion amount for each region according to the pre-calculated deviation trends, achieving accurate detection with simplified algorithms.
3Measurement precision
If extensive verification of algorithm and set values is performed for each sample, then measurement precision is improved, but time consumption increases and productivity deteriorates
Solution Approach 1:
The patent performs the verification work in advance by calculating the correction line from training data that represents typical deviation patterns. This pre-verification encapsulates the optimal algorithm parameters and search range settings, eliminating the need for time-consuming verification during actual production inspection of each sample.
Data Source
AI summary
A method of generating a correction line indicating a relationship between an amount of deviation of an edge of a wafer pattern from an edge of a reference pattern and a width of a space adjacent to the edge of the reference pattern, includes: creating an appearance-frequency graph of widths of spaces adjacent to reference patterns located within a designated area; obtaining images of wafer patterns corresponding to a plurality of space widths shown in the appearance-frequency graph; calculating amounts of deviation between edges of the wafer patterns on the images and edges of corresponding reference patterns; plotting a plurality of data points on a coordinate system, the plurality of data points being specified by the plurality of space widths and the amounts of deviation; and generating a correction line from the plurality of data points on the coordinate system.