The technique of surface acoustic waves (SAWs) is a very promising method for determining film properties such as Young’s modulus, density and film thickness nondestructively and accurately. The dispersion property of SAWs is also affected largely from the adhesion property of films, which is revealed by the bonding spring assumption described. This SAW method could offer a quantitative evaluation of the film adhesion from the curvature of SAW dispersion lines affected by the normal and shear spring constants. The method is applied to numerically characterize the adhesion property of the typical ultra-large-scale integrated circuit interconnect layered structure of a thin Cu film deposited on the Si substrate as well as a SiO2 thin film on a Si substrate.

Ultra-wide band (UWB) imaging technique is very attractive for the early breast cancer detection based on the obvious contrast in the electrical properties of malignant tumor to the normal fatty breast tissue. The tumor can be detected by analyzing the reflecting and scattering behavior of the UWB microwaves propagating in the breast. In this study, the influence of the organism interfaces is investigated from different cases of breast configuration involving different gland shapes as well as the tumor locations. Results show that the gland structure and tumor status have large influences on the reconstructed images generated from the detected signals due to the interface varieties. The tumor information in the proposed configurations can be obtained by series signal processing including eliminating the early time response of the detected signals caused by the direct wave and the reflection from the interface between the skin and the breast fat, and compensating the path loss of the propagating signal due to the radial spreading and the attenuation in the lossy breast. The location and the number of emitters and detectors affect the quality of the reconstructed image.

利用声表面波（SAW）的频散特性来表征超大规模集成电路（ULSI）互连系统中低介电常数（k）薄膜的物性具有准确、快速、对材料无损伤等突出优点。研究了Si（100）衬底上淀积低k薄膜的分层结构中，SAW沿任意方向传播的色散关系，引入坐标变换后，单层薄膜特征矩阵从9阶降到6阶，双层薄膜特征矩阵从15阶降到10阶，大幅度提高了计算速度，有利于生产ULSI过程中的在线监测。

The surface acoustic waves (SAWs) technique is becoming an attractive tool for accurately and nondestructively characterizing the mechanical property of the brittle low dielectric constant (low-k) thin film. The theoretical equations for describing SAWs propagating on the multi-layered structure are derived in this study. The dispersion features of SAWs propagating on different structures of low-k/SiO2/Si substrate, SiO2/low-k/Si substrate, low-k/Si substrate, and low-k/Cu/Si substrate are investigated to instruct an accurate and facile fitting process for determining Young’s modulus of low-k films. The dependence of dispersion relation on the film thickness, elastic modulus of low-k materials as well as frequency are provided and discussed in detail. The study shows an obvious influence of layered structure on the dispersion relation of SAWs. For a fixed structure, the dispersion curvature increases with the decrease of Young’s modulus of low-k films.

The surface acoustic waves (SAWs) technique is becoming an attractive tool for accurately and nondestructively characterizing the mechanical property of the fragile low dielectric constant (low-k) thin film used in the advanced ULSI multi-layer interconnects. The dispersion features of SAWs propagating on the layered structure of low-k/SiO2/Si substrate and low-k/Cu/Si substrate are investigated in detail. The influence of the film thickness on the dispersion curvature is provided as an instruction for an accurate and facile fitting process. Numerical results indicate that the mechanical property of low-k films is expected to determine effectively when the broadband frequency is up to 300 MHz.