Combinatorial Thin Film Synthesis for Developments of New High Dielectric Constant Thin Film Materials

Abstract

The development of high-dielectric constant thin film materials is essential for future active and passive nanoelectronics devices. Recently we developed high-dielectric constant thin film materials for thin film capacitor and gate dielectrics by combinatorial technique. Combinatorial thin-film of (1-x)[BaTiO 3 ]-x[Bi(Mg 2/3 Nb 1/3 )O 3 ]-(BT-BMN) was grown on Pt/SiO 2 /Si, using pulse laser deposition (PLD) method, by deviating from stoichiometry and Bi-10 wt% enriched targets to optimize the Bi content. X-ray photoelectron spectroscopy analysis revealed a linear Bi composition spread. As-deposited films post-annealed at high-temperatures under oxygen atmospheres turned into crystalline state and the crystallinity, characterized by the full width at half maximum of x-ray diffraction, is better towards Bi-enriched end. The dielectric constant showed a strong dependency of Bi composition and it increased with the increase of Bi and saturated over 7 wt% Bi. The scanning nonlinear dielectric microscopic investigation revealed that ferroelectric phase distribution is better around Bi-7 wt% region where the measured leakage current is also minimum. This tendency suggests that nonstoichiometric Bi concentration in the PLD target influences the thin-film electrical properties. Dielectric constant over 300 and dielectric constant stability below 10% from 25 to 400 °C were obtained.

Control of Lateral Composition Distribution in Graded Films of Soluble Solid Systems A1−xBx by Partitioned Dual-Beam Pulsed Laser Deposition

“…The alternate, wedgelike, submonolayer deposition of each material through a motor-driven shadowing mask enhances the precision of the spatial control of the composition (Figure 1a) [13]. Examples of lateral, compositionally-graded films prepared with masked sequential PLD include (1−x)LaMnO 3 -xSrMnO 3 films [3,14], (1−x)BaTiO 3 -xSrTiO 3 films [4,15], (1−x)BiFeO 3 -xGaFeO 3 films [16], and (1−x)BaTiO 3 -x[Bi(Mg 2/3 Nb 1/3 )O 3 ] films [17]. This method is advantageous in the preciseness of the design of lateral compositional evolution.…”