Characterization of elastic properties of SiO2 thin films by ultrasonic microscopy

This paper describes characterization of elastic properties of SiO
₂
films by the Line-Focus-Beam (LFB) ultrasonic microscopy. SiO
₂
films with 1 μm thickness were deposited on Si (001) substrates by sputtering or CVD with two different deposition conditions each, and the water-loaded SAW velocity on these samples was measured. Large variation of elastic properties was clearly observed among four specimens. Furthermore, anisotropy in the elastic properties was also observed. Namely, those normal to the surface seem different from those along the surface considerably. This anisotropy might be induced during the deposition.