SUMMARY
Non-destructive inspection methods have been crucial to the development of the micro-electronics packaging industry, aiding the industry in reducing manufacturing cost, improving yields, and ensuring product quality and reliability. New inspection techniques are needed to fill the gap between available inspection capabilities and the industry’s requirement for low-cost, fast-speed, and highly reliable inspection systems. The laser ultrasound inspection system under development aims to provide a solution that can overcome some of the limitations of current inspection techniques. The laser ultrasonic and interferometric inspection technique utilizes a high power pulsed laser to generate ultrasonic waves on the device surface and excite structural vibration. An interferometer is used to measure the vibration displacement of the chip’s surface at several inspection points. Since defective interconnects cause changes in the vibration of the device, quality can be assessed by comparing the vibration response of a known-good device to the response of the sample under inspectionThe research presented in this theses focuses on the continued development towards expanding the application scope to on-line high volume inspection. The following are the research objectives: 1) Develop a method used to analyze measurements taken with the laser ultrasonic and interferometric inspection system without requiring a previously established reference device. 2) Develop an excitation/measurement scheme capable of providing a strong vibration response in high density and stiff devices. The realization of these research objectives will improve the overall utility of the laser ultrasonic inspection technique to on-line inspection applications where no other non-destructive methods are currently available.