Dielectric properties of thin insulating layers measured by Electrostatic Force Microscopy

¹ Institut d'Électronique du Sud (IES), UMR CNRS 5214, Université Montpellier II, CC 082, Place E. Bataillon, 34095 Montpellier Cedex, France
² Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
³ Departamento de Física de Materiales UPV/EHU, Facultad de Química, Apartado 1072, 20080 San Sebastián, Spain
⁴ Université de Toulouse, INPT – CNRS, Institut de Mécanique des Fluides (IMFT), 1 allée du Professeur Camille Soula, 31400 Toulouse, France
⁵ Laboratoire de Microscopie en Champ Proche (LMCP), Centre de Technologie de Montpellier, Université Montpellier II, CC 082, Place E. Bataillon, 34095 Montpellier Cedex, France
⁶ Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center MPC, Edificio Korta, 20018 San Sebastián, Spain

Corresponding author: richard.arinero@ies.univ-montp2.fr

Received: 25 September 2009
Revised: 4 December 2009
Accepted: 16 December 2009
Published online: 26 February 2010

Abstract

In order to measure the dielectric permittivity of thin insulting layers, we developed a method based on electrostatic force microscopy (EFM) experiments coupled with numerical simulations. This method allows to characterize the dielectric properties of materials without any restrictions of film thickness, tip radius and tip-sample distance. The EFM experiments consist in the detection of the electric force gradient by means of a double pass method. The numerical simulations, based on the equivalent charge method (ECM), model the electric force gradient between an EFM tip and a sample, and thus, determine from the EFM experiments the relative dielectric permittivity by an inverse approach. This method was validated on a thin SiO₂ sample and was used to characterize the dielectric permittivity of ultrathin poly(vinyl acetate) and polystyrene films at two temperatures.