Microwave Characterization of Thin Film Titania

Open Access
Author:
Rankinen, Jeffrey L
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 20, 2005
Committee Members:
  • Mark William Horn, Committee Chair
  • Michael T Lanagan, Committee Chair
  • Lynn A Carpenter, Committee Member
  • Xiaoxing Xi, Committee Member
Keywords:
  • thin film characterization
  • high frequency dielectric constant
  • titanium dioxide
  • titania
  • microwave thin film characterization
  • high frequency permittivity
Abstract:
The demand for higher computing speeds and electronics miniaturization has made it necessary to investigate thin film dielectric materials that exhibit low loss at high frequencies. The measurement of dielectric properties using conventional methods generally is capable of providing accurate results up to approximately 1 GHz for thin film materials. The probe of the measuring instrument and contact resistance interfere with the acquisition of accurate high-frequency data. Indirect methods have been proposed and promise improved high frequency characterization of dielectric materials. My research will concentrate on further developing novel methods for accurately characterizing dielectric thin film materials at high frequencies (1 GHz to 26 GHz). Titanium dioxide will be used because of its high dielectric constant (up to 170). In this research the characterization of high k thin films will be investigated using the high k material titania (TiO2) on a fused quartz substrate. The study of titania on fused quartz is a logical low-cost method of establishing reproducible methods for high k microwave thin film characterization. The characterization techniques for thin films developed in this research will include use of the ring resonator, split-cavity resonator (dielectrometer) and coplanar transmission line. This paper investigates techniques not only to measure titania thin films, but most high k dielectric materials. Limitations to this technique will be described in detail in this paper. In this research, refinements to techniques for characterizing thin films are proposed that accurately determine relative permittivity and dielectric loss. Conventional techniques can suffer from high frequency effects and compromise accuracy. As the frequency of characterization enters the GHz range, refinements are necessary for accurate measurements.