Quantitative measurement of local elasticity of SiOx film by atomic force acoustic microscopy

In this paper the elastic properties of SiO_x film are investigated quantitatively for local fixed point and qualitatively for overall area by atomic force acoustic microscopy (AFAM) in which the sample is vibrated at the ultrasonic frequency while the sample surface is touched and scanned with the tip contacting the sample respectively for fixed point and continuous measurements. The SiO_x films on the silicon wafers are prepared by the plasma enhanced chemical vapour deposition (PECVD). The local contact stiffness of the tip-SiO_x film is calculated from the contact resonance spectrum measured with the atomic force acoustic microscopy. Using the reference approach, indentation modulus of SiO_x film for fixed point is obtained. The images of cantilever amplitude are also visualized and analysed when the SiO_x surface is excited at a fixed frequency. The results show that the acoustic amplitude images can reflect the elastic properties of the sample.