Inkjet-printed thin film radio-frequency capacitors based on sol-gel derived alumina dielectric ink
KAUST DepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Integrated Microwave Packaging Antennas and Circuits Technology (IMPACT) Lab
Permanent link to this recordhttp://hdl.handle.net/10754/623485
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AbstractThere has been significant interest in printing radio frequency passives, however the dissipation factor of printed dielectric materials has limited the quality factor achievable. Al2O3 is one of the best and widely implemented dielectrics for RF passive electronics. The ability to spatially pattern high quality Al2O3 thin films using, for example, inkjet printing would tremendously simplify the incumbent fabrication processes – significantly reducing cost and allowing for the development of large area electronics. To-date, particle based Al2O3 inks have been explored as dielectrics, although several drawbacks including nozzle clogging and grain boundary formation in the films hinder progress. In this work, a particle free Al2O3 ink is developed and demonstrated in RF capacitors. Fluid and jetting properties are explored, along with control of ink spreading and coffee ring suppression. The liquid ink is heated to 400 °C decomposing to smooth Al2O3 films ~120 nm thick, with roughness of <2 nm. Metal-insulator-metal capacitors, show high capacitance density >450 pF/mm2, and quality factors of ~200. The devices have high break down voltages, >25 V, with extremely low leakage currents, <2×10−9 A/cm2 at 1 MV/cm. The capacitors compare well with similar Al2O3 devices fabricated by atomic layer deposition.
CitationMcKerricher G, Maller R, Mohammad V, McLachlan MA, Shamim A (2017) Inkjet-printed thin film radio-frequency capacitors based on sol-gel derived alumina dielectric ink. Ceramics International. Available: http://dx.doi.org/10.1016/j.ceramint.2017.04.167.
SponsorsWe acknowledge financial support from King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR). We greatly appreciate and thank Dr. Mohammed Nejib for his work with the XPS analysis and interpretation of the results. For the help with MIM fabrication we thank the nanolab staff especially Ahad Syed for his guidance with amorphous silicon and ALD alumina deposition and etching. KAUST graduate students Armando “Arpys” Arvelo and Mincho Kavaldzhiev also provided sound advice during the fabrication. We thank Nini Wei and Shuai Yang for the work and assistance with SEM analysis of the films. Shawn Sanctis for his insights into working with alumina precursors and solvents. Finally we would like to thank Dr. Jaewon Jang for sharing his printing experience and hands on skills working with sol-gel oxides.