Jiro Naka

Step Coverage and Electrical Properties of (Ba, Sr)TiO3 Films Prepared by Liquid Source Chemical Vapor Deposition Using TiO(DPM)2

Thin films of (Ba, Sr)TiO3 (BST) with high dielectric constant were prepared on Pt/ SiO2/Si substrates of 6-inch-diameter by liquid source chemical vapor deposition using Ba(DPM)2, Sr(DPM)2 and TiO(DPM)2 (DPM=dipivaloylmethanato; C11H19O2) dissolved in tetrahydrofuran (THF). The reproducibility of ±3 % for the film composition was achieved by optimizing the deposition procedures. It was found that the coverage of 72%, obtained at the substrate temperature T s=753 K, was better than those obtained using other Ti sources such as Ti(O-i-Pr)4 (TTIP) and Ti(O-i-Pr)2(DPM)2. The electrical properties of the 480-A-thick BST film, deposited at T s=753 K using TiO(DPM)2, were as follows: dielectric constant e=230, equivalent SiO2 thickness t eq=7.8 A, leakage current density J L=6.7×10-6 A/cm2 at 1.65 V and dielectric loss tan δ=0.013.