Overview
IEC 62951-2:2019 is an international standard developed by the International Electrotechnical Commission (IEC) that focuses on the evaluation methods for flexible and stretchable semiconductor devices, specifically flexible thin-film transistors (TFTs). This standard defines comprehensive test procedures, key parameters, symbols, and configurations essential to accurately measure and assess the electron mobility, sub-threshold swing, and threshold voltage of flexible TFT devices, especially under mechanical bending conditions.
Flexible TFTs are semiconductor devices fabricated on mechanically flexible substrates such as polymers and metal foils, widely used in advanced electronics where bendability and stretchability are crucial. This standard supports assessing both the electrical performance and mechanical reliability of these devices in realistic operational environments involving bending stresses.
Key Topics
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Terms and Definitions
The standard provides clear terminology including flexible TFTs, electron mobility, sub-threshold swing, threshold voltage, gate voltage, drain voltage, drain current, and transconductance following international electrotechnical vocabulary.
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Test Procedures
- Electrical Characterization Before Bending: Conduct stability tests like Negative-Bias-Stress (NBS), Negative-Bias-Illumination-Stress (NBIS), Positive-Bias-Stress (PBS), and Positive-Bias-Illumination-Stress (PBIS). These tests measure drain current behavior with gate voltage sweeps at controlled temperatures and illumination conditions to extract parameters like field-effect mobility and threshold voltage.
- Electrical Characterization Under Bending: Measures device characteristics during and after bending with controlled radii of curvature to simulate real-world mechanical stresses, including both tensile and compressive strains.
- Measurement Setup: Specifies electrical circuit configurations and bending setups to ensure standardized data collection, enabling reliable and reproducible results.
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Characteristic Parameters
- Electron Mobility: Evaluates charge carrier velocity under electric field influence, vital for device switching performance.
- Sub-threshold Swing: Quantifies the rate at which the transistor switches off, essential for power efficiency and device responsiveness.
- Threshold Voltage: The gate-source voltage at which the device begins to conduct significantly, an important parameter for circuit design.
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Data Reporting
Test reports must include conditions like bending radius, measurement temperature, illumination intensity, and electrical characterization results for holistic device performance evaluation.
Applications
IEC 62951-2:2019 is critical for industries and researchers engaged in:
- Flexible and Wearable Electronics: Device manufacturers requiring standardized test protocols to assess TFT performance reliability under bending stresses common in wearable and foldable devices.
- Flexible Displays and Sensors: Ensuring TFT devices in flexible OLED displays or sensor arrays maintain performance and longevity after repeated mechanical deformation.
- Semiconductor Device R&D: Developing novel flexible materials and transistor architectures while benchmarking electrical and mechanical performance using internationally recognized evaluation methods.
- Quality Control: Facilitating conformity assessment and product validation for flexible semiconductors prior to market release.
This standard enhances practical use evaluation of flexible TFTs, supporting the innovation of next-generation flexible electronic products.
Related Standards
- IEC 60050-521: International Electrotechnical Vocabulary related to semiconductor devices, providing foundational definitions referenced by IEC 62951-2.
- Other Parts of IEC 62951 Series: Covering broader aspects of flexible and stretchable semiconductor devices, including fabrication and reliability testing not limited to TFTs.
- ISO/IEC Directives Part 2: Guidelines for the drafting and structure of international standards to which IEC 62951-2 adheres.
By using IEC 62951-2:2019, developers and engineers ensure globally harmonized measurement and evaluation methods that support flexible semiconductor device innovation and deployment effectively in various practical applications.
Open preview (PDF)Semiconductor devices - Flexible and stretchable semiconductor devices - Part 2: Evaluation method for electron mobility, sub-threshold swing and threshold voltage of flexible devices
