Overview
IEC 62899-503-3:2021 - Printed electronics - Part 503-3 defines a standardized, practical method for measuring contact resistance (Rc) of printed thin film transistors (TFTs) using the transfer length method (TLM). The standard specifies how to fabricate a Test Element Group (TEG) with varying channel lengths, how to perform measurements (using a current meter or SMU), and how to analyze and report results for quality assessment of electrode contacts in printed TFT devices.
Key topics and requirements
- Scope and purpose
- Quality assessment of TFT electrode contacts in printed electronics.
- Suited to determine whether contact resistance lies within a desired range.
- Test Element Group (TEG) preparation
- TEGs must use the same materials, device architecture and (ideally) substrate as the evaluated TFT.
- A set shall include four or more TEGs with different source–drain channel lengths (L).
- Measured L values should be between 0.5 and 5 times the channel length of the evaluated TFT; electrode width (W) should be 0.5–2 times that of the evaluated device.
- Measurement method
- Use the Transfer Length Method (TLM): measure total resistance for different L and extrapolate to L = 0 to extract contact resistance (y-intercept).
- Measurements are performed in the TFT linear regime and require appropriate drain and gate biasing.
- Measurement configurations may use a current meter or a Source Measure Unit (SMU).
- Apparatus, environment and data handling
- Standard specifies measuring apparatus considerations, environmental conditions and storage prior to measurement.
- Data analysis includes normalization of resistance values, plotting total resistance vs. L, and deriving Rc by extrapolation.
- Reporting
- Required reporting items include TEG details, measurement conditions, data analysis method and derived contact resistance.
Practical applications and users
- Who uses it
- Printed electronics manufacturers and suppliers
- Quality, reliability and process engineers
- Test labs and contract manufacturers
- R&D teams developing printed TFTs and materials
- Why it matters
- Enables consistent, repeatable assessment of TFT contact quality across supply chains.
- Helps diagnose process, material or design changes that affect device performance and lifetime.
- Cost-effective method for discrete-device testing without complex equipment.
Related standards
- This document is part of the IEC 62899 series (Printed electronics). Users should consult other parts of the series for complementary test and device specifications and check for the latest editions and related measurement standards.
Keywords: IEC 62899-503-3:2021, printed electronics, thin film transistor, TFT, contact resistance, transfer length method, TLM, Test Element Group, TEG, quality assessment.
Open preview (PDF)Printed electronics - Part 503-3: Quality assessment - Measuring method of contact resistance for the printed thin film transistor - Transfer length method
