Measurement of attraction force between AFM tip and surface of dielectric thin films with DC-bias

Abstract

The attraction force between the AFM tip and the surface of sputtered dielectric thin films (SiO 2 and ZrO 2) was measured with atomic force microscope (AFM) by applying DC-bias between the AFM tip and the n-Si substrate. Under 0 electric field, there exists van der Waals interaction between the AFM tip and the surface of dielectric films. When DC voltages are applied, the attraction force increases obviously for thin SiO 2 (5.2 nm) and ZrO 2 (6.8 nm) films due to the columbic interaction between them. A parallel-plate model has been developed to evaluate the ideal columbic tip-surface force for SiO 2 and ZrO 2 films. Contrary to the calculation result, the columbic force for ZrO 2 film (6.8 nm) is lower than that for SiO 2 film (5.2 nm), indicating the poor dielectric properties of the ZrO 2 film. The poor dielectric properties of ZrO 2 film should be due to the interfacial SiO x -containing layer formed between ZrO 2 and Si, supporting the conclusion reached in the literature that the interfacial SiO x -containing layer can deleteriously influence the dielectric properties of high- k films.