VC-EBI Test Patterns for Same-Type Source-Drain Short Detection
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Solution Overview
Problem
Current wafer-level testing techniques, such as VC-EBI, struggle to detect shorting between neighboring source or drain regions of the same doping type, which is a common defect in IC designs, as they do not result in electric charge transfer and hence are not detectable by existing methods.
Innovation Solution
Incorporating specially designed VC-EBI test patterns on semiconductor wafers that can detect shorting between adjacent source or drain structures by utilizing positive and negative mode VC-EBI imaging, allowing for the detection of electrical defects that traditional methods miss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional VC-EBI testing is used, then the testing process is simple, but it cannot detect shorting between same-type source or drain regions
Solution Approach 1:
The patent applies preliminary action by incorporating specially designed VC-EBI test patterns into the semiconductor wafer before fabrication is complete. These test patterns include opposite-type source or drain regions (e.g., N-type next to P-type) that are prepared in advance to enable detection of shorting defects between same-type regions through charge transfer mechanisms, allowing defect detection capability to be built into the testing process itself rather than requiring complex post-fabrication analysis
Solution Approach 2:
The patent uses an intermediary approach by introducing opposite-type source or drain regions as mediator structures in the test patterns. These opposite-type regions act as intermediaries that facilitate charge transfer when shorting occurs between same-type regions, making the otherwise undetectable defects visible through voltage contrast changes in the VC-EBI imaging process
2Measurement precision
If VC-EBI is used to detect electrical defects, then charge transfer is required for detection, but shorting between same-type regions does not produce charge transfer
Solution Approach 1:
The patent introduces opposite-type source or drain regions as intermediary structures that enable indirect detection of same-type shorting defects. When a short occurs between same-type regions (e.g., N-N short), the intermediary opposite-type region facilitates charge transfer through its adjacent junction, producing a detectable voltage contrast signal in VC-EBI images that reveals the presence of the otherwise invisible same-type shorting defect
Solution Approach 2:
The patent applies parameter changes by modifying the electrical parameters of the test structure through the use of opposite-type doping regions. This changes the electrical behavior of the test pattern so that same-type shorting defects, which normally produce no charge transfer, now produce detectable voltage changes through the intermediary opposite-type regions, enabling VC-EBI detection of these defects
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 the detection of shorting between same-type source or drain regions, improving the accuracy of wafer-level testing and reducing the likelihood of undetected defects in IC fabrication, thereby enhancing the quality control of semiconductor manufacturing.
Implementation Method 1
voltage contrast electron beam inspection (VC-EBI) test patterns
Implementation Method 2
applying an electron beam to the patterns
Data Source
AI summary
In a semiconductor manufacturing method includes providing a plurality of patterns on a semiconductor substrate. The patterns include an NMOS structure arranged next to an N+/N well structure, and/or a PMOS structure arranged next to a P+/P well structure. The method further includes: receiving a plurality of images by applying an electron beam to the patterns; and transferring the semiconductor substrate to a next process step if there is no image conversion according to a predetermined image contrast property of the patterns.