High sensitivity detection of ultrasonic signal for nondestructive inspection using pulse compression method

Abstract

Semiconductor parts are currently being stacked and miniaturized, and as device structures become more complicated, nondestructive inspections are increasingly needed for improving yield and securing reliability. Scanning acoustic microscopy (SAM) is used to detect delamination and voids. However, when the frequency of the ultrasonic probe is increased to improve the spatial resolution, conventional SAM cannot detect defects in deep parts because ultrasonic attenuation increases. In this research, we developed high sensitivity detection technique of ultrasonic signal using a pulse compression method, examined a modulation method, and designed the waveform of the transmitted signal to achieve high defect detection sensitivity. Conventional and developed detection techniques of ultrasonic signal were applied to a 3-layer stacked specimen, and their ultrasonic images, noise reduction effect, and defect detection sensitivity were compared.