Solid-Angle Imaging for Topography and Material Contrast Separation
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Solution Overview
Problem
Existing methods for determining topography and material contrast in microelectronics samples, such as lithographic masks, are limited by the inability to separate secondary electron and backscattered electron signals effectively, leading to inaccurate repair processes due to the averaging of solid and energy distributions, which complicates the detection of defects and repair control.
Innovation Solution
A method involving the recording of at least two image representations of a sample at different solid angles to decouple topography and material contrast using multiple detectors without energy filters, allowing for precise detection of local material composition and topography through a decoupling model or transformation model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single detector is used to record image representations, then the device complexity is reduced, but the measurement precision of topography and material contrast deteriorates due to averaging of solid and energy distributions
Solution Approach 1:
The patent divides the detection task into multiple detectors, each responsible for detecting secondary particles from specific solid angle ranges. This segmentation allows separate measurement of topography contrast and material contrast without signal averaging, resolving the technical contradiction between device simplicity and measurement precision.
Solution Approach 2:
The patent introduces the solid angle dimension as an additional parameter for differentiation. By recording image representations from different solid angle ranges, the system can separate topography and material contrast information that would be averaged in a single detector, achieving higher measurement precision without excessive complexity.
2Measurement precision
If energy filters are used in detectors, then the measurement precision of material contrast is improved, but the device complexity and loss of information increase due to filtering out useful signals
Solution Approach 1:
The patent extracts the solid angle differentiation function from the energy filtering function. Instead of using energy filters to separate material contrast information, the system uses multiple detectors viewing the sample from different solid angles, thereby extracting the necessary information without the complexity and information loss associated with energy filtering.
Solution Approach 2:
The patent uses the solid angle distribution of secondary particles as an intermediary parameter to separate topography and material contrast. This intermediary approach avoids direct energy filtering while achieving the same goal of precise material contrast detection, reducing device complexity and preserving information.
3Manufacturing precision
If local chemical repair processes are used, then the manufacturing precision of defect repair is improved, but the loss of time increases because these processes are slow-moving and require precise stopping control
Solution Approach 1:
The patent implements feedback control by using the separated topography and material contrast image representations as real-time indicators during the local chemical repair process. The material contrast image serves as a stop signal, allowing precise control of the repair process timing, thereby achieving high manufacturing precision without excessive time loss.
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 reproducible repair processes by separating topography and material contrast, reducing sample damage and improving the precision of defect detection in microelectronics samples.
Implementation Method 1
In order to repair local defects of a sample, usually at least one process gas is provided at the processing site on the sample at which a focused particle beam induces a local chemical reaction
Implementation Method 2
recording at least two image representations of a sample by irradiating a sample region with a focused particle beam in order to detach secondary particles that leave the sample at different solid angles
Data Source
AI summary
The present invention relates to a method and a device for determining a topography contrast and/or a material contrast of a sample. The method comprises the following steps: (a) providing at least two image representations of the sample recorded at least partly at different solid angles relative to the sample; and (b) determining the topography contrast and/or the material contrast of the sample at least partly on the basis of the at least two image representations of the sample.