Semiconductor Pattern Shape Evaluation Using Secondary Energy Beam Analysis
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Solution Overview
Problem
Current methods for measuring the cross-sectional shape of fine semiconductor circuit patterns are inadequate as they are either destructive, require extensive calculations, or have limited applicability to irregular patterns, and existing non-destructive methods suffer from resolution issues and complexity in data acquisition.
Innovation Solution
A method using a charged particle beam apparatus to obtain observation images of a substrate's upper surface, detecting secondary energy beam intensities, and estimating the cross-sectional shape by analyzing inclination angles and surface roughness from these images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cross-section observation is used to measure the shape of solid structures, then measurement accuracy is improved, but the measurement process becomes destructive
Solution Approach 1:
The patent creates a three-dimensional shape model (copy) of the solid structure based on two-dimensional observation images, allowing accurate shape measurement without physically cutting or destroying the original structure. The model-based library compares measured images with pre-calculated images of various three-dimensional shapes to determine the actual shape.
Solution Approach 2:
The patent replaces the mechanical cross-section cutting method with an optical/electronic imaging method using observation devices (such as SEM or optical microscopes). Instead of physically sectioning the structure to view its shape, the system uses light or electron beams to capture images and reconstruct the three-dimensional shape computationally.
2Object-affected harmful factors
If scatterometry or MBL method is used to estimate cross-sectional shape, then non-destructive measurement is achieved, but calculation complexity and time increase significantly
Solution Approach 1:
The patent pre-calculates and stores a library of observation images corresponding to various three-dimensional shapes and their parameters before actual measurement. During measurement, the system only needs to compare the captured image with this pre-existing library, dramatically reducing calculation time and complexity compared to performing full scatterometry or MBL calculations in real-time.
Solution Approach 2:
The patent transforms the complex inverse problem of shape reconstruction into a parameter matching problem. Instead of solving complex integral equations, the system varies parameters such as line width, height, and side wall angle in the model-based library, generates corresponding images, and matches them with measured images to find the best fit, simplifying the computational task.
3Object-affected harmful factors
If scatterometry or MBL method is used for shape estimation, then non-destructive measurement is enabled, but applicability is limited to periodic patterns
Solution Approach 1:
The patent creates a universal measurement system that can handle various pattern types (periodic, aperiodic, isolated lines, dense arrays) using the same model-based library approach. The system is not limited to periodic structures because it directly compares images without relying on diffraction theory assumptions that constrain scatterometry to periodic patterns.
Solution Approach 2:
The patent uses image-to-image comparison where the measured image is directly compared with pre-calculated images in the model-based library. This approach copies the visual appearance rather than relying on mathematical transformations, making it applicable to any pattern geometry that can be visually represented, regardless of periodicity.
4Object-affected harmful factors
If AFM is used to measure surface roughness, then non-destructive measurement is achieved, but resolution and measurement speed are insufficient for fine patterns
Solution Approach 1:
The patent replaces the mechanical scanning probe method (AFM) with an optical or electron beam imaging method. The observation device uses light or electron beams to capture images of the pattern surface, achieving higher resolution and faster measurement speeds while remaining non-destructive, unlike the mechanical contact method of AFM.
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 non-destructive estimation of cross-sectional shapes of arbitrary structures on a substrate, improving the precision and efficiency of semiconductor manufacturing by simplifying the data acquisition process and expanding applicability to complex patterns.
Implementation Method 1
detecting secondary energy beam intensities
Implementation Method 2
obtaining uncertainty information regarding an intensity of scattering caused by an irregular shape of a surface of the structure
Data Source
AI summary
A cross-sectional shape or a three-dimensional shape of a circuit pattern is estimated and evaluated only from a planar image of the circuit pattern observed from the above of a wafer. The present invention includes a process of obtaining an observation image of an upper surface of a solid structure, by causing the upper surface of a substrate to be irradiated and scanned with a converged energy beam from a direction substantially perpendicular to a main surface of the substrate having the structure formed on the upper surface thereof, and detecting and/or measuring intensities of a secondary energy beam generated in the substrate and the structure or an energy beam reflected or scattered from the substrate or the structure, a process of obtaining uncertainty information regarding an intensity of scattering caused by an irregular shape of a surface of the structure, from an irradiation position of the converged energy beam in the observation image of the upper surface and the measured intensity, a process of obtaining an inclination angle θ of the surface of the structure, based on the obtained uncertainty information; and a process of estimating a solid shape of the structure, based on the obtained inclination angle θ.