Dynamic Scan Angle Adjustment for Semiconductor Pattern Measurement
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Solution Overview
Problem
The accuracy of measuring complex pattern shapes in semiconductor device production is compromised due to the attraction of secondary electrons towards a positively charged substrate, making it difficult to determine clear peaks of secondary electrons on pattern edges, especially when the electron beam scan direction is parallel to the pattern edge.
Innovation Solution
A pattern shape measurement method that generates contour point data, calculates angles between marker lines and base lines, and determines a scan angle based on the frequency of these angles to minimize the likelihood of the electron beam being parallel to pattern edges, thereby enhancing the clarity of secondary electron peaks and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electron beam scans parallel to the pattern edge, then the scan direction aligns with the pattern orientation, but the secondary electron peaks become unclear due to attraction toward the positively charged substrate
Solution Approach 1:
The patent applies dynamics by making the scan angle adjustable rather than fixed. The electron beam scan angle is dynamically changed to be non-parallel with respect to the pattern edge orientation, allowing the system to adapt to different pattern geometries. This dynamic adjustment ensures that the beam never scans perfectly parallel to any pattern edge, thereby maintaining clear secondary electron peaks while preserving measurement speed.
Solution Approach 2:
The patent changes the scan angle parameter from a fixed value to a variable parameter that is deliberately set to be non-parallel with the pattern edge. By modifying this critical parameter, the system avoids the harmful effect of parallel scanning where secondary electrons are attracted to the substrate. This parameter change resolves the contradiction by maintaining measurement accuracy while preserving productivity.
2Ease of operation
If the scan angle is fixed, then the measurement process is simple, but the electron beam may be parallel to pattern edges causing unclear secondary electron peaks
Solution Approach 1:
The patent transforms the fixed scan angle into a dynamic, adjustable parameter. The scan angle is no longer fixed but is instead set to be non-parallel with respect to the pattern edge orientation. This dynamic approach maintains operational simplicity while preventing the parallel scanning condition that causes measurement errors, thus resolving the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The patent implements feedback by detecting the orientation of pattern edges and using this information to adjust the scan angle accordingly. The system identifies the pattern edge orientation and sets the scan angle to be non-parallel, creating a feedback loop that ensures accurate measurements. This feedback mechanism resolves the contradiction by automatically adapting to pattern geometries while maintaining simple operation.
3Adaptability or versatility
If complex pattern shapes are measured, then the measurement capability is advanced, but the accuracy deteriorates due to parallel scanning effects on pattern edges
Solution Approach 1:
The patent applies dynamics by making the scan angle adjustable rather than fixed. The electron beam scan angle is dynamically changed to be non-parallel with respect to the pattern edge, allowing the system to adapt to different pattern geometries. This dynamic adjustment ensures that the beam never scans perfectly parallel to any pattern edge, thereby maintaining clear secondary electron peaks while preserving measurement speed.
Solution Approach 2:
The patent changes the scan angle parameter from a fixed value to a variable parameter that is deliberately set to be non-parallel with the pattern edge. By modifying this critical parameter, the system avoids the harmful effect of parallel scanning where secondary electrons are attracted to the substrate. This parameter change resolves the contradiction by maintaining measurement accuracy while preserving productivity.
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 high-accuracy measurement of pattern shapes by reducing the probability of the electron beam being parallel to pattern edges, resulting in clearer secondary electron peaks and improved dimension measurement accuracy.
Implementation Method 1
a critical dimension scanning electron microscope (CD-SEM) is used. The CD-SEM scans a pattern being a measurement target with an electron beam and detects peaks of secondary electrons
Implementation Method 2
on a pattern edge extending substantially parallel to a scan direction of the electron beam, continuously generated secondary electrons are drawn toward a substrate that is positively charged
Data Source
AI summary
A pattern shape measurement method includes generating, based on shape data on a pattern being a measurement target, contour point data including pieces of position information on contour points of the pattern (e.g., mask pattern); selecting sets of pieces of position information on consecutive contour points from the contour point data and generating a plurality of items of extracted point data including the respective sets of pieces of position information on consecutive contour points; calculating, with circuitry, for each of the plurality of items of extracted point data, a determined angle formed between a marker line based on the consecutive contour points and a base line that extends in a prescribed direction in the pattern; determining a scan angle for the charged particles with respect to the pattern based on a frequency of occurrence of the determined angle; and scanning the pattern at the determined scan angle.