Laser-Based Fatigue Crack Growth Evaluation for Semiconductor Devices
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Solution Overview
Problem
Current methods for testing sub-critical fatigue crack growth in semiconductor devices are time-intensive, making them impractical for routine use in semiconductor manufacturing environments, and existing laser spallation techniques are not applicable for analyzing fatigue-related defects in these materials.
Innovation Solution
A method and system that uses repeated energy pulses from an energy source, such as a Nd:YAG laser, to induce controlled mechanical stress below a threshold in semiconductor devices, causing the formation and growth of sub-critical fatigue cracks, which are then detected to determine a pass or fail status based on a predefined benchmark of cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical fatigue testing methods are used, then accurate detection of sub-critical fatigue crack growth is achieved, but the testing process becomes time-intensive and impractical for routine manufacturing
Solution Approach 1:
The patent replaces traditional mechanical fatigue testing systems with a laser-based system. The laser delivers energy pulses that induce mechanical stress in the semiconductor device without requiring physical contact or complex mechanical testing apparatus. This substitution enables rapid fatigue testing while maintaining detection accuracy through optical detection methods.
Solution Approach 2:
The patent employs periodic laser energy pulses applied in repeated cycles to induce fatigue stress. The laser delivers energy pulses at specific intervals, creating cyclic mechanical stress that mimics real-world fatigue conditions. This periodic action allows for accelerated testing by delivering stress cycles much faster than traditional mechanical testing methods.
2Productivity
If laser spallation techniques are used for adhesion testing, then rapid testing is achieved, but the technique cannot be applied to fatigue crack growth analysis in semiconductor materials
Solution Approach 1:
The patent modifies the laser parameters (energy pulse characteristics, duration, intensity) to achieve the desired mechanical stress level for fatigue testing. By carefully controlling these parameters, the system can induce sub-critical fatigue cracks without causing immediate failure or excessive damage. This parameter optimization enables the laser system to be adapted specifically for fatigue crack growth analysis in semiconductor materials.
Solution Approach 2:
The patent creates a universal laser-based testing system that can be applied to multiple testing objectives including adhesion testing and fatigue crack growth analysis. The same laser system and detection methodology can evaluate different failure mechanisms in semiconductor devices, making the testing approach versatile and adaptable to various material characterization needs.
3Reliability
If repeated mechanical stress cycling is applied for extended periods, then comprehensive fatigue evaluation is achieved, but the testing time becomes excessively long for manufacturing environments
Solution Approach 1:
The patent implements continuous laser energy pulse delivery throughout the fatigue testing process, eliminating idle time between stress cycles. The laser system operates continuously to deliver energy pulses at high frequency, maintaining constant stress application on the semiconductor device. This continuous action accelerates the fatigue process while ensuring comprehensive evaluation coverage.
Solution Approach 2:
The patent applies preliminary laser energy pulses to pre-stress the semiconductor device before the main fatigue testing sequence. This preliminary action prepares the material structure to be more susceptible to subsequent fatigue damage, accelerating crack initiation and growth. By performing this preparation in advance, the overall testing duration is reduced while maintaining evaluation completeness.
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 rapid fatigue testing deployable in semiconductor manufacturing, allowing for timely detection and replacement of defective ICs, improving product reliability and reducing costs by enabling material selection, development, process control, and failure analysis.
Implementation Method 1
a plurality of energy pulses generated by an energy source are repeatedly impinged onto the semiconductor device. The repeated impinging of the plurality of energy pulses induces a mechanical stress within the semiconductor device
Data Source
AI summary
In a method and system for evaluating sub-critical fatigue crack growth in a semiconductor device, a plurality of energy pulses generated by an energy source are repeatedly impinged onto the semiconductor device for a predefined time interval. The repeated impinging of the plurality of energy pulses induces a mechanical stress within the semiconductor device. The induced mechanical stress, maintained below a threshold and repeated for a predefined number of cycles, causes a formation of a sub-critical fatigue crack within the semiconductor device. A detector detects the presence of the sub-critical fatigue crack leading to a fatigue failure. A rapid determination of a pass or fail status for a fatigue test of the semiconductor device is made by comparing a total number of cycles to fatigue failure to a predefined benchmark.