(Georgia Institute of Technology, 2008-10)
Davis, Cleon E.; Dickherber, Anthony; Hunt, William D.; May, Gary S.
Variable-frequency microwave (VFM) curing can perform the same processing steps as conventional thermal processing in minutes, without compromising intrinsic material properties. With increasing demand for novel dielectrics, there is a corresponding demand for new processing techniques that lead to comparable or better properties than conventional methods. VFM processing can be a viable alternative to conventional thermal techniques. However, current limitations include a lack of reliable temperature measuring techniques. This research focuses on developing a reliable temperature measuring system using acoustic techniques to monitor low-k polymer dielectrics cured on silicon wafers in a VFM furnace. The acoustic sensor exhibits the capability to measure temperatures from 20 degrees C to 300 degrees C with an attainable accuracy of ± 2 degrees.
(Georgia Institute of Technology, 2007-03-01)
Corso, Christopher D.; Dickherber, Anthony; Hunt, William D.
In recent years, interest in the development of highly sensitive acoustic wave devices as biosensor platforms has grown. A considerable amount of research has been conducted on AT-cut quartz resonators both in thickness excitation and in lateral excitation configurations. In this report, we demonstrate the fabrication of a ZnO solidly mounted resonator operated in thickness shear mode (TSM) using lateral field excitation of the piezoelectric film. Theoretical Christoffel equation calculations are provided to explore the conditions for excitation of a TSM wave in c-axis-oriented ZnO through lateral excitation. The existence of a TSM wave is verified through the comparison of theoretical and experimentally obtained acoustic velocity values from frequency versus thickness measurements and water loading of the resonators. A major strength of this design is that it incorporates a simple eight-layer, single-mask fabrication process compatible with existing integrated circuit fabrication processes and can be easily incorporated into multidevice arrays. With minimal electrode optimization, we have been able to fabricate resonators with nearly 100% yield that demonstrate Q values of up to 550 and K² values of 0.88% from testing of more than 30 devices.