Dielectric Properties of (Ba_xSr_1-x)TiO₃ Thin Films Prepared by RF Sputtering for Dynamic Random Access Memory Application

Abstract

Dielectric properties of (Ba0.5Sr0.5)TiO3 and (Ba0.75Sr0.25)TiO3 thin films have been investigated, focusing on the effects of film structure and Ba/Sr compositions on the dielectric properties. Dielectric constant of the films increased with increasing grain size and with improvement in film crystallinity. For the 50-nm-thick films deposited at 660° C, the dielectric constant of 400 for the (Ba0.5Sr0.5)TiO3 film is larger than that of 320 for the (Ba0.75Sr0.25)TiO3 film. This indicated that dielectric constant is affected by the ratio of Ba/Sr composition. Leakage current density of less than 1×10-7 A/cm2 at 1 V and SiO2 equivalent thickness of 0.38 nm are measured at 120° C for 660° C-deposited (Ba0.5Sr0.5)TiO3 film of 30 nm in thickness. The (Ba0.5Sr0.5)TiO3 film has the possibility for application to generations beyond 256 Mbit dynamic random access memories.

(Ba,Sr)TiO3 Thin Films for Dram’s

“…The capacitance density is limited by ttXb: making it the most important factor in achieving a high capacitance density. The small interface capacitance reported by Kuroiwa et al [27] was not replicated by Hwang et al [26] even though the top and bottom electrode, deposition technique, substrate temperature and composition (BaiSr ratio) were nomin'ally identical.…”

“…In this study, a higher temperature post top electrode anneal (750C versus 550°C) reduced the interfacial capacitance and increased the dielectric constant as shown in Table 6. The effect of BaiSr ratio (50/50 or 75/25) on teqr and EB [27] is also shown in Table 6. The values were calculated from published plots of teq versus thickness for BST films sputtered at 660°C [27].…”

“…The effect of BaiSr ratio (50/50 or 75/25) on teqr and EB [27] is also shown in Table 6. The values were calculated from published plots of teq versus thickness for BST films sputtered at 660°C [27]. The calculated EB was insensitive to the BaiSr ratio.…”

Physical and chemical characterization of barium strontium titanate thin films

“…A direct relationship between BST grain size and dielectric constant has been reported by several authors (6)(7)(8), therefore BST film grain size was the focus of many studies. Shown in Fig.…”

Controllable Growth of Ni Nanocrystals Embedded in BaTiO<sub>3</sub>/SrTiO<sub>3</sub> Superlattices

“…The dielectric matrix with the embedded metal NCs has widely potential application in nonlinear optical and electronic device [4,5]. Therefore, several methods have been considered to fabricate the BTO and STO-based material, including sol-gel [6], reactive evaporation [7], rf-sputtering [8] and laser ablation methods [9]. However, the controllable fabrication of nanostructure remains the daunting challenge for many deposition methods.…”