Semiconductor Test Device for High-Throughput Defect Inspection
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Solution Overview
Problem
Current defect inspection methods in semiconductor manufacturing, particularly for fine pattern defects, are inefficient due to the need for high resolution and small beam currents, which limits throughput and accuracy, and existing test structures are not fabricated using the same process as semiconductor devices, leading to unreliable results.
Innovation Solution
A test device using a charged particle beam in VC mode with a scanning pad on a dielectric layer and a test structure that mimics an electric circuit, allowing for large beam current and low resolution inspection, and can be fabricated using the same process as semiconductor devices, enhancing accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution inspection is used for fine pattern defects, then measurement precision is improved, but productivity deteriorates due to small beam current requirements
Solution Approach 1:
The inspection system is divided into two independent parts: a test device fabricated with the semiconductor device that captures defect signals, and a separate charged particle beam inspection tool that detects the signals. This segmentation allows the inspection tool to operate without being constrained by the resolution requirements of the fine pattern, enabling high beam current and high throughput while maintaining defect detection precision through the test device's voltage contrast signal.
Solution Approach 2:
A test device structure is introduced as an intermediary between the semiconductor device and the inspection tool. This test device includes signal capture structures (such as capacitively coupled nodes or resistively coupled nodes) that convert fine pattern defects into detectable voltage or current signals. The intermediary amplifies the defect signal, allowing the inspection tool to use large beam current without requiring direct high-resolution imaging of the fine pattern.
2Measurement precision
If small beam current is used for fine pattern inspection, then measurement precision is improved, but productivity deteriorates due to limited signal strength
Solution Approach 1:
The test device acts as a signal amplifier intermediary. When the charged particle beam scans the test device, the signal capture structures (capacitively or resistively coupled nodes) convert fine pattern defects into amplified voltage or current signals. This signal amplification allows the use of large beam current for fast scanning without sacrificing defect detection accuracy, as the test device structures enhance the defect signal strength.
Solution Approach 2:
The inspection method changes the detection parameter from direct optical/electronic signal detection to voltage contrast signal detection. By fabricating test device structures with specific electrical properties (capacitive coupling, resistive coupling), the system transforms the detection mechanism to one that is insensitive to beam current magnitude, allowing high beam current to be used for high-speed inspection while maintaining precision through voltage contrast imaging.
3Device complexity
If conventional test structures are used for defect inspection, then device complexity is reduced, but reliability deteriorates due to different fabrication processes
Solution Approach 1:
The test device is fabricated using the same semiconductor fabrication process as the actual semiconductor device, ensuring homogeneity in material properties, process variations, and defect characteristics. The test device structures (signal capture nodes, coupling elements) are integrated into the same wafer and undergo identical processing steps, making the test device representative of the actual device conditions and improving the reliability of defect detection.
Solution Approach 2:
The test device structure serves multiple functions: it acts as both a test structure for defect inspection and as part of the semiconductor device fabrication process. The same fabrication process creates both the functional semiconductor devices and the test device structures, allowing the test device to universally represent the process conditions and defect modes of the actual devices while maintaining process simplicity.
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 enables efficient identification of open/short circuit defects with increased throughput and accuracy by using VC mode inspection and identical fabrication processes, ensuring precise defect capture without the need for detailed scanning of fine patterns.
Implementation Method 1
these defects in the present invention can be inspected by using VC (voltage Contrast) mode instead of conventional pattern compare
Implementation Method 2
A test device using a charged particle beam in VC mode with a scanning pad on a dielectric layer
Data Source
AI summary
A structure, for defect inspection, is provided, which includes a scanning pad scanned by an electron beam inspection tool and a test key. The structure can be located in the scribe line. A virtual grounding pad is further provided if the test key is located in the dummy pattern regions.