Semiconductor Device Threshold Voltage Variation Measurement
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Solution Overview
Problem
Conventional methods for measuring threshold voltage in semiconductor devices underestimate variations due to relaxation of the voltage impact between the application and measurement phases, leading to unbalanced current flow and decreased efficiency.
Innovation Solution
A method involving continuous application of AC voltage with a maximum voltage equal to or higher than the threshold voltage, along with a constant voltage between the high and low potential sides, measures the variation in threshold voltage by monitoring the change in electric current, using a product of the current change and the inverse of the application time ratio to accurately determine the threshold voltage variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage is applied to the gate for an arbitrary period and then measurement is performed after suspension, then threshold voltage variation can be measured, but the measurement time is extended and the voltage impact relaxes leading to underestimation of threshold voltage variation
Solution Approach 1:
The patent applies AC voltage continuously to the gate during the entire measurement process without suspension, eliminating the relaxation period between voltage application and measurement. This continuous action ensures the voltage impact remains active throughout measurement, preventing underestimation of threshold voltage variation while reducing total measurement time.
Solution Approach 2:
The patent uses AC voltage with a specific frequency applied continuously to the gate, leveraging periodic voltage cycles to maintain the voltage impact throughout the measurement process. The periodic nature of AC voltage ensures continuous stimulation of the semiconductor device while enabling accurate threshold voltage variation measurement without time delays.
2Productivity
If voltage application and measurement are performed in separate phases, then measurement can be conducted, but current flow becomes unbalanced and efficiency decreases
Solution Approach 1:
The patent maintains continuous AC voltage application to the gate throughout the measurement process, eliminating interruptions that cause current flow unbalance. This continuous operation ensures stable electrical conditions and balanced current flow between source and drain, improving both measurement efficiency and electrical stability.
Data Source
AI summary
A method of evaluating a semiconductor device having an insulated gate formed of a metal-oxide film semiconductor. The semiconductor device has a high potential side and a low potential side, and a threshold voltage that is a minimum voltage for forming a conducting path between the high and low potential sides. The method includes determining a variation of the threshold voltage at turn-on of the semiconductor device by continuously applying an alternating current (AC) voltage to the gate of the semiconductor device, a maximum voltage of the AC voltage being equal to or higher than the threshold voltage of the semiconductor device.