multilayer transfer matrix characterization of complex materials with scanning acoustic microscopy

Open Access
Author:
Kim, Jeong Nyeon
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 13, 2013
Committee Members:
  • Richard Laurence Tutwiler, Thesis Advisor
  • Bernhard R Tittmann, Thesis Advisor
  • Victor Ward Sparrow, Thesis Advisor
Keywords:
  • scanning acoustic microscopy
  • V(z) curve
  • surface acoustic wave
  • multilayer transfer matrix
  • reflectance function
  • adhesive condition
Abstract:
A multilayer structured thin film system, such as a biomedical thin film, Micro Electric Mechanical System (MEMS) / Nano Electric Mechanical System (NEMS) devices, and semiconductors, is widely used in various fields of industry. To non-destructively evaluate the multilayer structured thin film system, a mechanical scanning acoustic reflection microscope has been well recognized as a useful tool in recent years. Especially, the V(z) curve method with the scanning acoustic microscope is used to characterize the very small area of the system. In this study, V(z) curve simulation software has been developed for simulating a transducer’s output when we transmit an ultrasound wave into the specimen. In the software, the Thompson-Haskell transfer matrix method is applied to solve for the reflectance function. All input and output interfaces were incorporated in a Graphical User Interface (GUI) for users’ convenience. Surface acoustic wave velocities were calculated from the simulated V(z) curves. For the precise calculation advanced signal processing techniques were utilized. The surface acoustic wave velocity is compared to that from an experiment with a bulk solid. I also tested the simulation’s thickness sensitivity by simulating models with different thicknesses in the nanoscale. A series of experiments with multilayered solids were carried out and the results were compared with the simulation results. It was the first time a comparison was performed of analytical versus experimental V(z) curves for a multilayered system. For the multi-layered specimen, silicon (100) was used as a substrate. Titanium (thickness: 10 nanometer) and platinum (thickness: 100 nanometer) were deposited respectively.