Overview
IEC 62047-16:2015 is an international standard published by the International Electrotechnical Commission (IEC) that specifies standardized test methods to determine residual stresses in micro-electromechanical systems (MEMS) thin films. The standard focuses on films with thicknesses ranging from 0.01 µm to 10 µm. It covers two key mechanical test methods: wafer curvature and cantilever beam deflection. These methods are critical for evaluating residual stresses that can affect MEMS device reliability, performance, and fabrication yield.
Measuring residual stresses in MEMS films accurately is essential because these stresses influence device behavior, structural integrity, and long-term stability. IEC 62047-16:2015 provides a uniform framework for testing and reporting residual stress using these practical, widely adopted characterization techniques.
Key Topics
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Residual Stress in MEMS Films
Residual stress is the stress remaining in a thin film after the original cause of stress-such as mechanical forces or thermal effects-has been removed. Understanding these stresses is vital to optimize MEMS device design and manufacturing processes.
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Wafer Curvature Method
This method measures the curvature induced in a wafer after the deposition of a thin film. The curvature correlates with in-plane residual stresses in the film using Stoney’s equation. The method assumes biaxial and isotropic stress states and requires knowledge of the substrate’s mechanical properties including Young’s modulus and Poisson’s ratio. It is suitable for wafer-level, large-area stress measurement.
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Cantilever Beam Deflection Method
This approach determines residual stress based on the deflection of microfabricated cantilever beams coated with the thin film under test. The stress causes measurable bending in the cantilever, which can be used to calculate stress values at a smaller scale, often ideal for localized film stress assessments.
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Test Apparatus and Procedures
The standard details apparatus requirements for both test methods, including equipment calibration, measurement techniques, and data acquisition. It also specifies mandatory reporting parameters to ensure consistent and reproducible results across different laboratories and manufacturing sites.
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Assumptions and Limitations
The document outlines key assumptions for the methods’ applicability: uniform film and substrate thickness, material isotropy, small deformations, and negligible edge effects. These criteria ensure analytical accuracy when calculating residual stresses.
Applications
IEC 62047-16:2015 is developed specifically for semiconductor and MEMS industries where thin film quality and mechanical properties affect device function. Typical application areas include:
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MEMS Sensor and Actuator Fabrication
Ensuring film stress does not cause unwanted deformation or failure in accelerometers, gyroscopes, pressure sensors, optical MEMS, and RF MEMS devices.
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Microelectronics Packaging and Thin Film Deposition
Controlling residual film stresses in coatings, dielectric layers, and metallization used in microelectronic device structures.
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Research and Development
Supporting device engineers and researchers in characterizing novel materials and film stacks used in emerging MEMS technologies.
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Quality Control in Manufacturing
Implementing consistent residual stress measurement protocols to maintain process control and reliability in high-volume MEMS production.
Related Standards
IEC 62047-16:2015 connects with other standards and technical references to provide a comprehensive understanding of MEMS material properties:
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IEC 62047-21: Semiconductor devices – Micro-electromechanical devices – Part 21: Test method for Poisson’s ratio of thin film MEMS materials. This is essential for accurately determining substrate and film mechanical properties integrated in residual stress calculations.
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International and industry-specific standards on thin film deposition, mechanical testing, and MEMS reliability assessments also complement IEC 62047-16 for complete device characterization.
Keywords: IEC 62047-16, residual stress measurement, MEMS films, wafer curvature method, cantilever beam deflection, thin film testing, micro-electromechanical devices, Stoney’s equation, thin film mechanics, semiconductor device testing, mechanical stress in MEMS.
Open preview (PDF)Semiconductor devices - Micro-electromechanical devices - Part 16: Test methods for determining residual stresses of MEMS films - Wafer curvature and cantilever beam deflection methods
