Characterization of wafers by V(Z) curve technique of scanning acoustic microscopy

Abstract

The report presents the work performed on the evaluation of Young’s Modulus using the V(z) curve technique. The background of V(z) curve technique in determining the material properties non-destructively is introduced. In order for readers to understand the procedures undertaken for the project, a chapter for the necessary knowledge has been allocated.

The velocity of the surface acoustic waves and Young’s Modulus have been obtained from the V(z) curves measured by point-focus acoustic microscopy. Investigation on the repeatability of the technique was performed on wafers. The system’s repeatability is determined by using statistical studies. In-homogeneity effect inherent in the specimens was analyzed using the V(z) curve technique. Consistency plots of the measured Young’s Modulus and Rayleigh velocities were used to evaluate the technique’s sensitivity. The effects of different frequencies using different acoustical lenses were also investigated.

In addition, the accuracy of the V(z) curve technique was evaluated based on a comparison between the values of Young’s Modulus V(z) curve technique and it’s theoretical value of the material. Lastly, it has been observed that V(z) curve technique has its own merits and limitations. Hence, in the end of this report, some recommendations were made for future project to eliminate those limitations and enhance the excellence of the technique.