Effects of Bottom Electrode on the Structural and Electrical Characteristics of Barium Titanate Thin Films

概要

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Barium titanate thin films of 50nm thickness and having a composition of Ba(Zr_<0.12>Ti_<0.88>)O_3(BZT) were deposited on different electrodes of LaNiO_3(LNO), Pt and RuO_2 by rf magnetron sputtering at 400℃. Highly crystallized and (100)-oriented BZT films were formed by deposition on the (100)-textured LNO electrode, but poorly crystallized films were obtained by deposition on the other two electrodes. The films deposited on LNO were smooth and had a flat interface that epitaxially bonded with the LNO electrode. However, the films deposited on Pt or RuO_2 were rough and had a rugged film/electrode interface. High interdiffusion was found at the BZT/RuO_2 interface, but not at the other two interfaces. The dielectric constant of the film on LNO was 〜250, but that of the films on Pt or RuO_2 was 〜120. For the former, a high and stable insulating characteristic against biasing voltage was also found, i.e., a low leakage current of 10^<-9>A/cm^2 was maintained before reaching a high onset voltage of 5V. In contrast, the leakage current rapidly increased to > 10^<-7>A/cm^2 with increasing bias to 5V or 2V for the films deposited on Pt or RuO_2, respectively. The relationship of current versus time (J-t) measured at 380K also revealed the superior insulating property of the film deposited on LNO compared to the other two films.
社団法人応用物理学会の論文
1998-07-15