Transistor Reliability Testing via Hysteresis Analysis
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Solution Overview
Problem
Conventional methods for evaluating the reliability of transistors, such as the bias-temperature stress test (BT test), are time-consuming, stressful, and cannot accurately assess transistors that have undergone previous stress tests, leading to inefficiencies in manufacturing semiconductor devices with high reliability.
Innovation Solution
A test method that analyzes the hysteresis characteristics of transistors by measuring current between the drain and source electrodes while irradiating with light and changing the gate-source voltage, allowing for the determination of transistor reliability through Vg-Id curve comparisons, which correlates with BT test results, enabling a faster and more accurate assessment of transistor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a BT test is performed to evaluate transistor reliability, then the reliability assessment is thorough, but the test takes a long time and requires many samples
Solution Approach 1:
The patent creates a correlation between hysteresis characteristics (measured quickly) and BT test results (thorough but time-consuming). By measuring hysteresis as a copy or proxy indicator that correlates with reliability, the method achieves thorough assessment without the time cost of actual BT tests
Solution Approach 2:
The patent changes the measurement parameter from direct BT test conditions (high stress, long duration) to hysteresis characteristics under light irradiation (lower stress, short duration). This parameter substitution maintains assessment thoroughness while dramatically reducing test time
2Measurement precision
If a BT test is applied to transistors that have already undergone stress testing, then previous test results are affected, but re-testing is necessary for accurate evaluation
Solution Approach 1:
The patent performs hysteresis measurement as a preliminary screening step before final reliability assessment. This preliminary action identifies transistors that need further evaluation, preventing wasted effort on already-failed devices and maintaining manufacturing efficiency
Solution Approach 2:
The patent segments the reliability assessment into two stages: initial hysteresis screening (quick, non-destructive) and conditional BT re-testing (thorough but time-consuming). This segmentation ensures measurement precision only for necessary cases, preserving productivity
3Measurement precision
If high stress BT tests are used to detect low-reliability transistors, then detection accuracy is high, but the stress damage prevents use in end products
Solution Approach 1:
The patent uses hysteresis characteristics as a copy or indicator that reflects reliability issues without applying destructive stress. The measurement captures reliability information through electrical characteristics under light irradiation, avoiding the physical damage caused by high-stress BT tests
Solution Approach 2:
The patent introduces hysteresis measurement under light irradiation as an intermediary method between non-destructive inspection and destructive BT testing. This intermediary approach provides sufficient detection accuracy while preserving transistor usability for end products
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 method allows for the detection of low-reliability transistors with low stress and high accuracy in a shorter time than traditional BT tests, enabling the efficient manufacturing of semiconductor devices with high reliability by distinguishing between 'Good' and 'Not-Good' transistors through hysteresis characteristics measured under light irradiation.
Implementation Method 1
measuring the current (Id) between a drain electrode and a source electrode of the transistor while irradiating the transistor with light
Data Source
AI summary
Provided is a test method by which a transistor whose reliability is low can be detected with low stress and high accuracy in a shorter period of time than a BT test. Provided is to detect a transistor whose reliability is high in a shorter period of time than a BT test and manufacture an electronic device with high reliability efficiently. Hysteresis characteristics revealed in the result of the Vg-Id measurement with light irradiation to the transistor correlate with the result of a BT test; whether the reliability of the transistor is Good or Not-Good can be judged. Accordingly, the test method by which a transistor whose reliability is low can be detected with low stress and high accuracy in a shorter period of time than a BT test can be provided.