Fast Characterization Of The Young's Modulus Of Low-k Film By LSAWs

In the past several decades, the density of integrated circuit increased exponentially following Moore's law, characteristic size reduced continuously. At the present stage, RC delay of interconnect has been far more than the device delay, become the key factor which affect the performance and speed of circuit. To reduce the RC delay, more and more people pay attention to low dielectric constant (low-k) materials in the field of microelectronics. But lower dielectric constant often followed by lower mechanical strength, which limits the low-k material's application in integration system.This paper detects the Young's modules of low-k material by using Laser-generated Surface Acoustic Waves (LSAWs) method. Comparing with the traditional nano-indentation technology, LSAWs is a more favored technique to determine the Young's modules of fragile, soft, and ultra-thin film for the merits of quickness, preciseness and non-destructive.Surface Acoustic Waves (SAWs) is generated by using laser irradiate the film-substrate structure sample, detecting and getting the SAWs, the dispersion curve can be calculated according to the dispersion characteristics when SAWs propagating in layered media. On the base of the established film-substrate theoretical model, the theoretical dispersion curves corresponding to different Young's modulus can be calculating, finding a theoretical dispersion curve which most similar to the experiment one, and the actual parameters of thin films can be obtained.Through the optimization of the experimental system, our group has got SAWs which signal-noise ratio more than 10:1. After the surface wave signals were filtered, the smooth experimental dispersion curves with correct trend could be obtained. It has achieved repeatability in many experiments very well. Besides, matching procedure was design to search the most similar theoretical dispersion curve fast and accurately. Furthermore, simple and intuitive graphical user interfaces were built for the realization of online testing.