SEM Angle Discrimination for Non-Destructive Cross-Sectional Shape Estimation
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Solution Overview
Problem
Current methods for estimating the cross-sectional shape of semiconductor patterns, such as those using SEM, face challenges in measuring depth and complexity, particularly with reverse tapers and high aspect ratios, leading to issues with measurement throughput, reproducibility, and the need for destructive inspections.
Innovation Solution
A system utilizing a scanning electron microscope with a scanning deflector, signal electronic aperture, and angle discriminator to generate angle discrimination images, allowing for non-destructive estimation of cross-sectional shapes by analyzing changes in signal waveforms at different detection angles, enabling the calculation of taper angles and side wall shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TEM or cross-sectional observation methods are used to measure pattern side wall shape, then measurement accuracy is improved, but the inspection process becomes destructive and time-consuming
Solution Approach 1:
The patent creates a virtual cross-sectional image by processing SEM signal waveforms obtained from the top surface, replacing the need for physical cross-sectional sampling. The arithmetic device generates depth-resolved information through signal processing, producing a digital copy of the cross-sectional structure without physical sectioning
Solution Approach 2:
The patent replaces the mechanical/physical cross-sectional preparation process with an electronic signal processing system. Instead of physically sectioning the sample with a microtome or FIB, the system uses SEM signal waveforms and arithmetic processing to extract cross-sectional shape information non-destructively
2Loss of time
If SEM is used for non-destructive inspection, then measurement time is reduced, but the ability to measure depth and complex shapes like reverse tapers is insufficient
Solution Approach 1:
The patent extracts depth information (z-dimension) from two-dimensional top surface SEM observations. By analyzing the angular distribution of secondary electrons and backscattered electrons in signal waveforms, the system reconstructs three-dimensional cross-sectional shape information including depth, enabling measurement of high aspect ratios and reverse tapers from top-view data
3Measurement precision
If the acceleration energy of the charged particle ray is changed to estimate side wall shape, then shape information is improved, but measurement throughput decreases due to focus adjustment requirements
Solution Approach 1:
The patent changes the detection angle parameter instead of the acceleration energy parameter. By using an angle discriminator to separate electrons by emission angle and analyzing signal waveforms at different detection angles, the system obtains side wall shape information without changing beam energy, thereby eliminating focus adjustment requirements and maintaining high measurement throughput
4Measurement precision
If multiple detection angles are used to improve cross-sectional shape estimation, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the electron signal by emission angle using an angle discriminator, separating secondary electrons and backscattered electrons into different detection channels. This angular segmentation allows independent analysis of electron signals from different depth regions, enabling accurate cross-sectional shape reconstruction without requiring multiple physical detectors
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 accurate and efficient non-destructive estimation of cross-sectional shapes, including reverse tapers and high aspect ratios, improving measurement throughput and reducing costs associated with destructive inspections.
Implementation Method 1
a scanning electron microscope (SEM: Scanning Electron Microscope) used for semiconductor inspection/measurement
Implementation Method 2
irradiating a sample with a charged particle beam, signal electrons emitted while the charged particle beam is scanned
Implementation Method 3
separating detected electrons obtained by normal electron ray irradiation by an angle (elevation angle)
Data Source
AI summary
The present disclosure provides a pattern cross-sectional shape estimation system which includes a charged particle ray device which includes a scanning deflector that scans a charged particle beam, a detector that detects charged particles, and an angle discriminator that is disposed in a front stage of the detector and discriminates charged particles to be detected, and an arithmetic device that generates a luminance of an image, and calculates a signal waveform of a designated region on the image using the luminance. The arithmetic device generates angle discrimination images using signal electrons at different detection angles, and estimates a side wall shape of a measurement target pattern.