Conductivity Extraction Using a 180 GHz Quasi-Optical Resonator for Conductive Thin Film Deposited on Conductive Substrate

• Published in: Materials Vol. 13; no. 22; p. 5260
• Main Authors: Ye, Ming, Zhao, Xiao-Long, Li, Wei-Da, Zhou, Yu, Chen, Jia-Yi, He, Yong-Ning
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 20.11.2020; MDPI
• Subjects: Aluminum; Bilayers; conductive thin film; Direct current; Electrical resistivity; Laboratories; Magnetic thin films; Methods; microwave effective conductivity; noncontact; Optical resonators; R&D; Research & development; Silicon wafers; substrate; Substrates; Thickness; Thin film coatings; Thin films
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13225260

Measurement of electrical conductivity of conductive thin film deposited on a conductive substrate is important and challenging. An effective conductivity model was constructed for a bilayer structure to extract thin film conductivity from the measured Q-factor of a quasi-optical resonator. As a demonstration, aluminium films with thickness of 100 nm were evaporated on four silicon wafers whose conductivity ranges from ~101 to ~105 S/m (thus, the proposed method can be verified for a substrate with a wide range of conductivity). Measurement results at ~180 GHz show that average conductivities are 1.66 × 107 S/m (which agrees well with direct current measurements) with 6% standard deviation. The proposed method provides a contactless conductivity evaluation method for conductive thin film deposited on conductive substrate which cannot be achieved by the existing microwave resonant method.