Application of ultrasonic computed tomography to nondestructive inspection of SiO2 ingot material qualities

Abstract

It is very important industrially to produce SiO2 chips with uniform material qualities for integrated circuit elements (IC). Therefore, nondestructive inspection to detect whether the material quality of the SiO2, column ingot is uniform or not is necessary before it is cut into a small chip for IC elements. For this purpose, the x-ray CT technique is effective. However, the technique is dangerous for workers in usual factories. Therefore, ultrasonic CT was tried for such detection. The ultrasonic CT was already developed using data from the time of flight (TOF) and applied to certain cases; for example, nondestructive inspection of rotten parts or hidden knobs in a cedar log and the measurement of internal temperature distribution. In this paper, an attept was made to use the ultrasonic CT for the nondestructive inspection of SiO2 column ingots. The experiment was made with an ultrasonic transducer at 5.0 MHz. The results show the usefulness of the TOF ultrasonic CT for the nondestructive inspection of SiO2 column ingots.