Complementary split ring resonator based RF sensor for sheet resistance characterization of conductive nanometric films

This paper presents a complementary split ring resonator (CSRR) based sensor for non-contact sheet resistance characterization of conductive nanometric films. Through full-wave simulations, we observed the dependence of Q-factor of CSRR on sheet resistance of conductive film which is placed on top of the CSRR. Results show that the Q-factor of the CSRR decreases monotonously with increasing sheet resistance. Experiments were performed with a CSRR resonating at around 1.9 GHz. Silver films, with sheet resistance ranging from ~0.1 Ohm/sq to ~1 Ohm/sq, were sputtered on 1.1 mm thick glass. Sheet resistances of these silver films were measured using standard four-point probe test. Experimental results agree qualitatively well with simulations and quantitatively match with the proposed fitting formulas describing relationship between Q-factor and sheet resistance. Therefore, it is possible to obtain sheet resistance from measured Q-factor along with the fitting formula. The proposed sensor is low cost and non-contact, which may be applied to applications relating to conductive thin film characterizations.