(Ba, Sr)TiO₃ Films Prepared by Liquid Source Chemical Vapor Deposition on Ru Electrodes

Abstract

Electrical properties of (Ba, Sr)TiO3 [BST] films have been investigated on RuO2/Ru and Ru electrodes instead of Pt, because they are easy to be etched. BST films were deposited at a substrate temperature of T s=420° C and a reactor pressure of P=1.5 Torr by employing a two-step liquid source chemical vapor deposition (CVD) process. BST films on RuO2/Ru were electrically shorted, which was considered to be caused by surface roughening during BST film deposition and/or post-annealing. In the case of Ru electrodes, an equivalent SiO2 thickness of t eq=0.50 nm (a dielectric constant of ε r=190), a leakage current of J L=4.6×10-8 A/cm2 at +1.1 V, and a dielectric loss of tan δ=0.018 were achieved at a total film thickness of 250 Å, by restricting Ru surface oxidation and its surface roughening. Moreover, BST film deposition on Ru storage nodes, 0.24 µ m wide, 0.6 µ m deep, 0.15 µ m high, and each spaced by 0.3–0.14 µ m, verified that the storage capacitance can be successfully increased by using sidewalls of the storage node, without a significant increase in the leakage current.

Effect of K-doping on the dielectric and tunable properties of Ba0.6Sr0.4TiO3 thin films prepared by RF magnetron sputtering

“…Though BST thin films are characterized by a lower loss tangent and higher tunability, there are several problems such as that high tunability of BST thin films is accompanied by a high loss tangent [6,7]. It is important to improve the dielectric properties of BST thin films.…”

Electrical properties of sputtered (Ba, Sr)TiO3 thin films prepared by two-step deposition method

“…For MOCVD method, the two step technique was applied to suppress protrusions of the BST films, where the main layer was deposited after annealing of first layer, seed layer. 4 Also, conventional two-step sputtering method was that a main layer was deposited after postannealing of the first layer. 6 For both MOCVD and sputtering method, the electrical properties were improved by a two-step method, but they did not report the electrical and structure properties according to thickness and deposition temperature of seed layer.…”

Structural and electrical characteristics of highly textured oxidation-free Ru thin films by DC magnetron sputtering

“…Ru and RuO 2 thin films have been receiving much attention because of their good conductivity, low temperature coefficient of resistance (TCR), and high thermal stability [7]. Therefore, they have been investigated for many applications such as diffusion barriers for oxygen [8,9], thin film resistors, and electrode materials for ferroelectric oxides [10][11][12]. Recently, there has been increasing interest in the deposition of metallic Ru films as well as in the study of RuO 2 film because Ru film can be used as an adhesion layer for a diffusion barrier as well as an electrode for dynamic random access memory (DRAM).…”