Acoustic MEMS Component Testing for Encapsulated Defect Detection
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Solution Overview
Problem
Existing methods for testing Micro-Electro-Mechanical Systems (MEMS) components are inefficient, as they often require expensive equipment, are time-consuming, and cannot detect defects in encapsulated structures, leading to increased production costs due to late detection of defects.
Innovation Solution
A method and apparatus for acoustically testing MEMS components using a test device that excites the components to acoustic oscillation and detects these oscillations with sound sensors, allowing for functional testing before and after encapsulation, and at various stages of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical testing methods are used to test MEMS components, then testing can be performed on mechanical movement, but the equipment is very expensive and measurements are time-consuming
Solution Approach 1:
The patent replaces optical testing methods with acoustic testing methods. Instead of using expensive optical equipment like stroboscopes to detect mechanical movement, the invention uses acoustic excitation and acoustic sensing to test MEMS components. This substitution eliminates the need for complex optical systems while achieving comparable or superior testing capability, and significantly reduces measurement time through parallel testing of multiple components.
Solution Approach 2:
The patent combines multiple testing functions into a single acoustic testing system. The test head integrates acoustic excitation sources and acoustic sensors to simultaneously perform both excitation and detection functions. Additionally, the system can test multiple MEMS components in parallel on a single wafer, merging what would otherwise require multiple separate testing operations into one efficient process.
2Measurement precision
If optical testing equipment is used for small MEMS structures, then mechanical functionality can be tested, but the equipment is very expensive
Solution Approach 1:
The patent replaces expensive optical testing equipment with acoustic testing equipment. The acoustic excitation source (such as a speaker or piezoelectric actuator) and acoustic sensors (such as microphones or piezoelectric sensors) are significantly cheaper than optical systems like stroboscopes and laser interferometers. This substitution maintains testing capability while dramatically reducing equipment costs, making MEMS testing more accessible and economical.
3Difficulty of detecting and measuring
If optical testing is performed on encased or capped MEMS, then internal structures can be examined, but current methods are limited in range and cannot fully examine larger chips
Solution Approach 1:
The patent replaces optical testing methods with acoustic testing methods for examining encased MEMS structures. Acoustic waves can penetrate encapsulation materials and travel through the device structure, allowing detection of internal defects and functionality without requiring optical access. This substitution overcomes the fundamental limitation of optical methods that cannot penetrate opaque encapsulation, enabling comprehensive testing of entire wafers or large chip areas.
Solution Approach 2:
The acoustic testing system is designed to be universally applicable to various MEMS structures and packaging types. The same acoustic excitation and detection setup can test different MEMS device types, different encapsulation materials, and different chip sizes without requiring specialized equipment configurations. This universality allows full examination of large chips and entire wafers, unlike optical methods that are limited by form factor and access requirements.
4Measurement precision
If electrical measurements are performed on MEMS with very small currents, then electrical functionality can be tested, but the resistances are very high and integration times are long
Solution Approach 1:
The patent replaces electrical measurement methods with acoustic testing methods. Instead of measuring very small currents and high resistances that require long integration times, the system uses acoustic excitation to drive the MEMS device and acoustic sensing to detect the response. This substitution transitions from electrical domain measurements to acoustic domain measurements, achieving faster testing without the limitations of high-impedance electrical measurements.
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
Enables efficient, cost-effective, and comprehensive testing of MEMS components at wafer level and during production, detecting defects early and reducing production costs by integrating acoustic testing into semiconductor manufacturing processes.
Implementation Method 1
exciting the at least one MEMS component to an acoustic oscillation with the test device
Implementation Method 2
detecting the acoustic oscillation of the at least one MEMS component with at least one sound sensor of the test device
Data Source
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AI summary
Embodiments relate to a method for acoustically testing at least one MEMS component of a plurality of MEMS components. The method has a step of providing at least one MEMS component, a step of exciting the at least one MEMS component so as to produce an acoustic vibration, a step of detecting the acoustic vibration of the at least one MEMS component using at least one acoustic sensor, and a step of evaluating the acoustic vibration of the at least one MEMS component detected using the at least one acoustic sensor in order to test the at least one MEMS component for a target functionality.