Charged Particle Beam Inspection for Plug-to-Plug Short Detection
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Solution Overview
Problem
Current charged particle beam inspection methods struggle to distinctly identify plug-to-plug short defects in semiconductor devices due to similarities in voltage contrast patterns with leakage defects, especially when defective plugs are aligned parallel to the line-to-line advancement direction, leading to confusion in grey level images.
Innovation Solution
The method involves scanning a sample with a charged particle beam in multiple directions to obtain multiple grey level images, comparing these images to identify abnormal plug patterns, and applying image processing techniques such as addition and subtraction to enhance contrast between plug-to-plug short and leakage defects, thereby distinguishing between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-direction charged particle beam scanning is used to obtain grey level image, then inspection speed is maintained, but defect identification accuracy deteriorates due to inability to distinguish plug-to-plug short from leakage defect
Solution Approach 1:
The patent applies multi-directional scanning by acquiring grey level images at different scanning directions (e.g., 0度和45度). This adds a dimensional aspect to the inspection process, allowing defects to be distinguished based on their response to scanning from different directions. Plug-to-plug shorts and leakage defects exhibit different voltage contrast patterns when scanned from different angles, enabling accurate differentiation.
Solution Approach 2:
The patent changes the scanning direction parameter to acquire multiple grey level images. By varying this parameter, the voltage contrast patterns of different defect types become distinguishable. The comparison of images obtained under different scanning conditions allows for accurate defect identification while maintaining a relatively simple inspection process.
2Measurement precision
If multi-directional scanning is performed to obtain multiple grey level images, then defect identification accuracy is improved, but inspection time increases
Solution Approach 1:
The patent performs scanning at a limited number of specific directions (e.g., 0度和45度) rather than exhaustive multi-directional scanning. This partial action approach provides sufficient information to distinguish defect types while minimizing the additional inspection time required. The selected directions are optimized to maximize defect differentiation capability.
3Device complexity
If conventional single-direction scanning is used, then inspection process remains simple, but voltage contrast patterns of different defects become indistinguishable
Solution Approach 1:
The patent introduces the scanning direction as an additional dimension to capture defect characteristic information. By acquiring images at multiple directions, sufficient information is obtained to distinguish between plug-to-plug shorts and leakage defects, preventing information loss while maintaining process simplicity through the use of limited, strategically selected scanning angles.
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
This approach effectively differentiates plug-to-plug short defects from leakage defects by enhancing the visibility of abnormal voltage contrast patterns, improving the accuracy of defect identification in semiconductor device inspection.
Implementation Method 1
a charged particle microscopic image is formed from secondary charged particles released by the sample while it is bombarded with a primary charged particle beam
Implementation Method 2
the presence of defects, i.e., abnormal physical and electrical characteristics of the sample, can be represented in the form of voltage contrast (VC)
Data Source
AI summary
A method of inspecting for plug-to-plug short (short circuit) defects on a sample is disclosed. A charged particle beam for imaging the sample is repeatedly line-scanned over the sample with a line-to-line advancement direction perpendicular to the line-scan direction. The method includes scanning the sample with a line-to-line advancement along a first and a second direction, to obtain a first and a second image of the sample, respectively. Then, the method includes identifying plug patterns, represented in the obtained images with abnormal grey levels, as abnormal plug patterns. Next, the method compares the locations of the abnormal plug patterns to determine the presence of plug-to-plug short defects on the sample.