Our goal is to develop the metrology to enable a materials genomic approach to the discovery and optimization of complex electronic and electromagnetic materials. To advance these goals we apply measurement-based approaches to rapidly determine the electromagnetic, thermal, and mechanical properties of complex thin-film materials, interfaces, and microstructures. Reliable, quantitative data for the relevant material parameters are critical to achieve accurate modeling of device performance for microelectronic circuits and applications. Our approach relies heavily on a generalized description of the material parameters (such as permittivity, heat capacity, elasticity) that explicitly includes nonlinear, inhomogeneous, and anisotropic behavior, and which can also incorporate non-equilibrium and quantum effects.
We approach this multidimensional characterization problem by developing measurement-based techniques to rapidly quantify all of the relevant properties of thin-film materials, interfaces, and microelectronic structures. We make extensive use of finite-element simulations, as well as linear and non-linear circuit models, in order to determine consistent material properties from measurements of ensembles of planar or microelectronic devices, and supplement device-based characterization with spatially-resolved measurements where possible. These measurement-based material descriptions can then be compared and combined with results of computational approaches to provide more complete models of complex systems, which are then used in the subsequent intelligent design and optimization of electronic materials, devices, and systems, and as a basis for new materials discovery.
Our measurement-based approach makes use of standardized, microfabricated test structures, such as planar transmission lines and simple lumped-element components. We then apply wafer-probe-based measurements as well as scanned-probe approaches to quantify different material parameters for a given material orientation. We have developed a comprehensive suite of measurements to access the multiple different material parameters most relevant for modeling device performance:
Booth, J. C.; Orloff, N. D.; Cagnon, J.; Lu, J. & Stemmer, S.,"Temperature-dependent dielectric relaxation in bismuth zinc niobate thin films," Applied Physics Letters 97, 022902 (2010).
Orloff, N. D.; Tian, W.; Fennie, C. J.; Lee, C. H.; Gu, D.; Mateu, J.; Xi, X. X.; Rabe, K. M.; Schlom, D. G.; Takeuchi, I. & Booth, J. C., "Broadband dielectric spectroscopy of Ruddlesden-Popper Srn+1TinO3n+1 (n=1,2,3) thin films," Applied Physics Letters 94, 042908 (2009).
Booth, J. C.; Orloff, N. D.; Mateu, J. & Takeuchi, I., "Methods of characterization of broadband dielectric properties, challenges in device fabrication and measurement," in Ferroelectric Films at Microwave Frequencies, edited by Jackson, T.; Suherman, P. & Bao, P., (Research Signpost, Kerala, 2010).
Collado, C.; Rocas, E.; Padilla, A.; Mateu, J.; O'Callaghan, J.; Orloff, N.; Booth, J.; Iborra, E. & Aigner, R., "First-Order Elastic Nonlinearities of Bulk Acoustic Wave Resonators,"IEEE Transactions onMicrowave Theory and Techniques, 59, 1206-1213 (2011).
Rocas, E.; Collado, C.; Booth, J. C.; Iborra, E. & Aigner, R., "Unified Model for Bulk Acoustic Wave Resonators Nonlinear Effects," Proceedings of the IEEE International Ultrasonics Symposium (IUS 2009), 2009.
Orloff, N.; Mateu, J.; Murakami, M.; Takeuchi, I. & Booth, J. C., "Broadband Characterization of Multilayer Dielectric Thin-Films," 2007 IEEE/MTT-S International Microwave Symposium Digest, 1177-1180 (2007).
Rocas, E.; Collado, C.; Mateu, J.; Orloff, N.; O'Callaghan, J. M. & Booth, J. C., "A Large-Signal Model of Ferroelectric Thin-Film Transmission Lines," IEEE Transactions on Microwave Theory and Techniques 59, 3059-3067 (2011).
Rocas, E.; Collado, C.; Orloff, N.; Mateu, J.; Padilla, A.; O'Callaghan, J. & Booth, J., "Passive Intermodulation Due to Self-Heating in Printed Transmission Lines,"IEEE Transactions on Microwave Theory and Technique 59, 311-322 (2011).
Booth, J. C.; Orloff, N. D. & Mateu, J., "Measurement of the Microwave Nonlinear Response of Combined Ferroelectric-Superconductor Transmission Lines," IEEE Transactions on Applied Superconductivity 19, 940-943 (2009).
Mateu, J.; Collado, C.; Orloff, N.; Booth, J. C.; Rocas, E.; Padilla, A. & O'Callaghan, J. M., "Third-Order Intermodulation Distortion and Harmonic Generation in Mismatched Weakly Nonlinear Transmission Lines,"IEEE Transactions on Microwave Theory and Techniques 57, 10-18 (2009).
We rely on collaborations with universities, industry, and government agencies to obtain physical samples of different material systems and microstructures, and work closely with these collaborators to improve material growth and fabrication processes by quantifying relevant electromagnetic material properties. Examples of material systems of interest include
We also actively seek collaborations with theoretical and computational material scientists in order to quantitatively compare experimental descriptions of material parameters with ab-initio calculations and results of other computational approaches. Such collaborations not only provide important experimental verification for computational approaches to material parameter determinations, but also help to guide and focus experimental investigations.