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

Abstract

Thin films of (Ba, Sr)TiO 3 (BST) with high dielectric constant were prepared on Pt/ SiO 2 /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; C 11 H 19 O 2 ) 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-Å-thick BST film, deposited at T s =753 K using TiO(DPM) 2 , were as follows: dielectric constant ε =230, equivalent SiO 2 thickness t eq =7.8 Å, leakage current density J L =6.7×10 -6 A/cm 2 at 1.65 V and dielectric loss tan δ=0.013.