Pattern Measuring Apparatus for Close Contour Separation
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Solution Overview
Problem
Existing measuring techniques for semiconductor devices struggle to accurately identify and measure pattern contours that are close to each other, leading to incorrect measurements due to overlapping brightness changes and interference between upper and lower layer patterns, especially in miniaturized semiconductor devices where contours are as close as a few nanometers.
Innovation Solution
A pattern measuring apparatus and method that acquires multiple SEM images under different imaging conditions, extracts and reconstructs pattern contours, and uses these reconstructed contours for accurate measurement, allowing for correct selection and measurement of contours even when they are close together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple layer patterns are simultaneously captured in an SEM image to enable efficient measurement, then measurement efficiency is improved, but measurement precision deteriorates due to contour interference between layers
Solution Approach 1:
The patent segments the measurement process by acquiring multiple SEM images under different imaging conditions (different focus positions, beam energies, or detection modes) and then selectively extracting contours from appropriate images. This segmentation allows efficient multi-layer measurement while maintaining precision by avoiding contour interference in any single image.
Solution Approach 2:
The patent introduces an additional dimension of imaging conditions (focus position, beam energy, detection mode) to differentiate between overlapping patterns from different layers. By varying these conditions, patterns from different layers become distinguishable, enabling accurate contour extraction while maintaining measurement efficiency.
2Measurement precision
If imaging conditions are optimized to capture one layer clearly, then measurement precision for that layer is improved, but the ability to capture other layers deteriorates
Solution Approach 1:
The patent creates a universal measurement system that can handle multiple layers by acquiring images under multiple imaging conditions. Each imaging condition is optimized for specific layers, but the system as a whole can measure any layer or combination of layers by selecting appropriate images and contours, achieving both precision and versatility.
Solution Approach 2:
The patent changes imaging parameters (focus position, beam energy, detection mode) to optimize visibility of different layers. By systematically varying these parameters and selecting the optimal combination for each measurement target, the system achieves high precision for individual layers while maintaining the capability to measure multiple layers.
3Device complexity
If conventional single-image contour extraction is used, then device complexity is minimized, but measurement precision deteriorates due to overlapping contours from multiple layers
Solution Approach 1:
The patent performs preliminary actions by acquiring multiple images under different imaging conditions before contour extraction. This preliminary multi-condition imaging separates the overlapping contours that would otherwise be mixed in a single image, enabling accurate contour identification without requiring complex real-time analysis.
Solution Approach 2:
The patent creates multiple copies of the sample image under different imaging conditions. Each copy highlights different layers or features, and the system selects the appropriate copy for contour extraction. This approach maintains relative simplicity while dramatically improving contour identification accuracy by avoiding the complexity of analyzing a single overlapping image.
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
Enables precise measurement of pattern contours by reducing errors associated with overlapping brightness changes and interference, improving measurement accuracy in miniaturized semiconductor devices by correctly identifying and separating contours that were previously difficult to distinguish.
Implementation Method 1
irradiates a measurement sample with an electron beam while scanning and detects a signal electron (secondary electron and backsattered electron) secondarily obtained from the measurement sample
Implementation Method 2
detects a signal electron (secondary electron and backsattered electron) secondarily obtained from the measurement sample
Data Source
AI summary
There is provided a technique to correctly select and measure a pattern to be measured even when contours of the pattern are close to each other in a sample including a plurality of patterns on a substantially same plane.A pattern measuring apparatus that scans a sample with charged particles, forms a detected image by detecting secondary charged particles or backscattered charged particles generated from the sample, and measures a pattern imaged on the detected image includes: an image acquiring section acquiring a plurality of detected images taken at a substantially same location on the sample under different imaging conditions; a contour extracting section extracting a plurality of pattern contours from the plurality of detected images; a contour reconstructing section reconstructing a contour to be measured by combining the plurality of pattern contours; and a contour measuring section making a measurement using the reconstructed contour to be measured.