SEM 3D Reconstruction of Semiconductor Height Profiles
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Solution Overview
Problem
Current semiconductor fabrication processes face challenges in accurately measuring and detecting defects in submicron features due to the need for high precision and uniformity, which is not adequately addressed by existing examination methods.
Innovation Solution
A system and method using a processor and memory circuitry to obtain images of semiconductor specimens at different illumination angles, determining height values by solving an optimization problem that accounts for differences in grey level intensity and illumination angles, allowing for precise reconstruction of the height profile without requiring topo-points or a priori knowledge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images are acquired at different illumination angles to improve height profile reconstruction precision, then measurement precision is improved, but examination time and processing complexity increase
Solution Approach 1:
The patent performs preliminary spatial alignment of images at different illumination angles before height profile reconstruction. By pre-aligning the images using feature matching and transformation algorithms, the system prepares the data in advance, reducing the computational burden during the actual reconstruction process and enabling faster examination while maintaining high precision
Solution Approach 2:
The patent transforms the two-dimensional image data from multiple illumination angles into three-dimensional height profile information through optimization-based reconstruction. This dimensional transformation allows the system to extract comprehensive surface topology data efficiently, improving measurement precision without requiring excessive examination time
2Manufacturing precision
If optimization problems with multiple functions are solved to determine height values from grey level intensity differences, then manufacturing precision is improved, but device complexity and processing time increase
Solution Approach 1:
The patent segments the complex optimization problem into multiple independent or loosely coupled functions, each handling specific aspects of height value determination from grey level intensity differences. This segmentation allows the system to solve simpler sub-problems separately, reducing overall computational complexity while maintaining manufacturing precision
Solution Approach 2:
The patent transforms the image data into different parameter representations (grey level intensities, spatial coordinates, illumination angles) and uses these transformed parameters in the optimization process. By changing parameters strategically, the system simplifies the mathematical relationships and reduces processing complexity while preserving measurement accuracy
3Measurement precision
If spatial alignment processes are performed on grey level intensity data, then measurement precision is improved, but examination time increases
Solution Approach 1:
The patent performs spatial alignment as a preliminary step before height profile reconstruction. By pre-aligning the grey level intensity data from different illumination angles using feature matching and geometric transformation, the system eliminates the need for repeated alignment operations during reconstruction, reducing total examination time while improving measurement precision
Solution Approach 2:
The patent replaces traditional mechanical or manual alignment methods with automated computational algorithms that use grey level intensity patterns and feature detection. This substitution enables rapid, precise spatial alignment through software-based image registration, significantly reducing processing time compared to manual methods while maintaining high accuracy
Data Source
AI summary
There is provided a system and a method comprising obtaining a first (respectively second) image of an area of the semiconductor specimen acquired by an electron beam examination tool at a first (respectively second) illumination angle, determining a plurality of height values informative of a height profile of the specimen in the area, the determination comprising solving an optimization problem which comprises a plurality of functions, each function being representative of a difference between data informative of a grey level intensity at a first location in the first image and data informative of a grey level intensity at a second location in the second image, wherein, for each function, the second location is determined with respect to the first location, or conversely, when solving the optimization problem, wherein a distance between the first and the second locations depends on the height profile, and the first and second illumination angles.