Semiconductor Threshold Voltage Measurement via Kelvin Probe
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Solution Overview
Problem
Current methods for measuring the threshold voltage of semiconductor devices in fabrication processes lack accuracy and efficiency, particularly in determining the effective work function of gate electrodes, which is crucial for quality control in mass production.
Innovation Solution
A method involving the formation of fin patterns and gate electrodes on a substrate, with a measurement region for contact potential difference (Vcpd) measurement to determine the threshold voltage, utilizing a work-function layer and low-resistance layer with an optimized effective area ratio, and employing a kelvin probe for precise measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used for threshold voltage, then the measurement process is simple, but the measurement accuracy is insufficient
Solution Approach 1:
The substrate is divided into a device region and a measurement region, with separate fin patterns and gate electrodes in each region. The measurement region contains dedicated test structures that can be measured independently without affecting the device region, enabling accurate threshold voltage measurement while keeping the device fabrication process intact.
Solution Approach 2:
A work-function layer is introduced as an intermediary element between the gate electrode and the channel. This work-function layer with optimized effective area ratio (85%-183%) serves as a mediator that enables accurate contact potential difference measurement through the Kelvin probe technique, thereby improving threshold voltage measurement accuracy.
2Reliability
If in-line monitoring is implemented for quality control, then the quality control effectiveness is improved, but the measurement time and complexity increase
Solution Approach 1:
The measurement region and test structures are prepared in advance during the fabrication process, before the actual threshold voltage measurement is needed. The work-function layer is deposited and structured beforehand with the optimal effective area ratio, so that when in-line monitoring is performed, the measurement can be conducted quickly using the pre-prepared test structures without adding significant time to the fabrication process.
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 enhances the measurement accuracy of threshold voltage, enabling rapid and effective in-line monitoring of semiconductor device quality, improving the reliability and efficiency of semiconductor device fabrication.
Implementation Method 1
measuring a contact potential difference (Vcpd) of the second gate electrodes to determine a threshold voltage of the first gate electrodes based on the measured contact potential difference (Vcpd)
Data Source
AI summary
A method of fabricating a semiconductor device includes forming first and second fin patterns in an active region and in a measurement region of a substrate, respectively, the measurement region being different from the active region, forming first and second gate electrodes to cross the first and second fin patterns, respectively, and measuring a contact potential difference (Vcpd) of the second gate electrode to determine a threshold voltage of the first gate electrode based on the measured contact potential difference (Vcpd).