MOS Transistor Measurement Using Withstand Voltage Correlation
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Solution Overview
Problem
The measurement of on-resistance in MOS transistors is affected by contact resistance between the electrode and the probe, leading to varying results, particularly in MOS transistors that pass a large current.
Innovation Solution
A method of measuring MOS transistors using a correlation between the on-resistance and a withstand voltage or threshold voltage, under conditions where the contact resistance is minimized, allowing for accurate measurement of these characteristics without directly measuring the on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large current is passed through the MOS transistor during on-resistance measurement, then the measurement reflects actual use conditions, but contact resistance between the electrode and probe/stage causes measurement variation
Solution Approach 1:
The patent introduces an intermediary parameter (threshold voltage or withstand voltage) that can be measured without the harmful contact resistance effect. Instead of directly measuring on-resistance with large current that causes contact resistance, the patent measures threshold voltage or withstand voltage which are not affected by contact resistance, then uses pre-established correlations to derive the on-resistance value. This intermediary approach eliminates the direct conflict between using large current and avoiding contact resistance errors.
Solution Approach 2:
The patent performs preliminary actions by pre-establishing correlation data between on-resistance and threshold voltage (or withstand voltage) under controlled conditions where contact resistance is minimized. These correlation relationships are stored and later used to convert measurements taken under different conditions (where contact resistance is negligible) into accurate on-resistance values, allowing the system to benefit from both low-contact-resistance measurement conditions and large-current test conditions.
2Measurement precision
If contact resistance is minimized during measurement, then measurement precision improves, but the ability to simulate actual use conditions with large current is compromised
Solution Approach 1:
The patent uses threshold voltage or withstand voltage as intermediary parameters that bridge the gap between low-contact-resistance measurement conditions and large-current operational conditions. These intermediary measurements can be taken with minimal contact resistance influence, yet they correlate to the device's performance under actual large-current use conditions through pre-established relationship data.
Solution Approach 2:
The patent changes the measurement parameter from on-resistance (which requires large current and suffers from contact resistance) to threshold voltage or withstand voltage (which can be measured with small current and are not affected by contact resistance). By measuring different electrical parameters and using correlation data, the system achieves both high measurement precision and reliability representing actual device performance.
Data Source
AI summary
A method of measuring a characteristic of a semiconductor device that is a first metal-oxide-semiconductor (MOS) transistor using a stage. The method includes: obtaining a first correlation between a characteristic, and a withstand voltage, of each of a plurality of second MOS transistors, the characteristic being measured under a condition that, for each second MOS transistor, a contact resistance between the stage, at which the second MOS transistor is placed, and an electrode of the second MOS transistor, is equal to or lower than a predetermined rate of an on-resistance of the second MOS transistor; measuring a withstand voltage of the first MOS transistor when the first MOS transistor is off; and outputting the characteristic of the first MOS transistor, using the first correlation and the measured withstand voltage of the first MOS transistor.