Electrical Studies on Parylene-C Columnar Microfibrous Thin Films

Future advances in solid-state device technology are dependent on innovations in multifunctional materials and novel deposition processes and, hence, a wide spectrum of new material compositions and morphologies are being explored. For this study, microfibrous thin films (µFTFs) of Parylene C  [1,2] were deposited on top of p-type Si substrates using physicochemical vapor deposition in a PDS2010 Labcoater to form metal-insulator–semiconductor (MIS) and metal–insulator–metal (MIM) capacitor structures utilizing the Parylene-C µFTF as the gate dielectric. Each µFTF was deposited with a collimated vapor flux of Parylene-C monomers inclined at 60° to the substrate plane and had a thickness of about 100 µm. The Parylene-C µFTFs were characterized for electrical properties and dielectric integrity using leakage current, equivalent series resistance and reactance, capacitance measurements at temperatures ranging from –40 °C to 125 °C and frequencies ranging from 1 kHz to 1 MHz, as well as field-emission scanning electron microscopy. The observed variations in leakage current can be explained in terms of transport mechanisms involving thermionic emission and electron hopping. Capacitance and dielectric loss data were analyzed. We found that higher leakage current does not allow for a reliable estimation of the dielectric constant.

[1] Pursel, S., Horn, M. W., Demirel, M. C., & Lakhtakia, A. (2005). Growth of sculptured polymer submicronwire assemblies by vapor deposition, Polymer, 46(23), 9544–9548.

[2] Chindam, C., Wonderling, N. M., Lakhtakia, A., Awadelkarim, O. O., & Orfali, W. (2015). Microfiber inclination, crystallinity, and water wettability of microfibrous thin-film substrates of Parylene C in relation to the direction of the monomer vapor during fabrication, Applied Surface Science, 345(1), 145–155.