Dielectric Properties of (Ba x Sr 1-x )TiO 3 Thin Films Prepared by RF Sputtering for Dynamic Random Access Memory Application

• Published in: Japanese Journal of Applied Physics 1994-09, Vol.33 (9S), p.5187
• Main Authors: Kuroiwa, Takeharu, Tsunemine, Yoshikazu, Horikawa, Tsuyoshi, Makita, Tetsuro, Tanimura, Jyunji, Noboru Mikami, Noboru Mikami, Kazunao Sato, Kazunao Sato
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.33.5187

Dielectric properties of (Ba 0.5 Sr 0.5 )TiO 3 and (Ba 0.75 Sr 0.25 )TiO 3 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 (Ba 0.5 Sr 0.5 )TiO 3 film is larger than that of 320 for the (Ba 0.75 Sr 0.25 )TiO 3 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/cm 2 at 1 V and SiO 2 equivalent thickness of 0.38 nm are measured at 120° C for 660° C-deposited (Ba 0.5 Sr 0.5 )TiO 3 film of 30 nm in thickness. The (Ba 0.5 Sr 0.5 )TiO 3 film has the possibility for application to generations beyond 256 Mbit dynamic random access memories.