The Influence of Electrodes Deposition on the Interface and Dielectric Characteristics of Polymer Gate for Thin Films Transistors

Abstract

The paper presents some results on the effect of the metal electrode deposition on the electrical performance of amorphous polymthylmetacrylate (PMMA) thin films, measured in a MIM structure consisting of metal (Al)-insulator (PMMA)-metal (Ta). Aluminium (Al) electrode was deposited by physical vapor deposition method (PVD) on the top of PMMA film with the deposition rate of 5 and 10Å/s. The effect of aluminium deposition rate and post deposition annealing temperature on the morphology of the interface between Al electrode (100 or 300 nm thick) and PMMA thin film (40 or 70 nm thick) has been investigated by cross-section scanning electron microscopy (SEM). Based on SEM data, I-V characteristic measurements and dielectric constant values of insulating films, the deposition parameters of Al top-electrode was optimised. Our results showed that when the deposition of the Al electrode take place at a rate of 10 Å/s, no inter-diffusion or interfacial reaction at the interface between Al electrode and PMMA films were observed and the best delectric parameters of PMMA thin film were measured, which led to the best dielectric performance of PMMA layer in TFT configuration.