(Ba_<0.75>Sr_<0.25>)TiO_3 Films for 256 Mbit DRAM (Special Issue on Quarter Micron Si Device and Process Technologies)

概要

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Thin (Ba_<0.75>Sr_<0.25>)TiO_3 (BST) films to be used as dielectric materials in 256 Mbit DRAM capacitors were investigated. These films were deposited by an rf-sputtering method at substrate temperatures of 480 to 750℃. As substrate temperature increases, the dielectric constant of the films also increases, from to 550. BST films prepared at temperatures higher than ℃ show larger current leaks than films prepared at lower temperatures. A dielectric constant of 250, corresponding to a silicon oxide equivalent thickness (t_<ep>) of 0.47 nm, and a leak current density about 1×10^<-8> A/cm^2 were obtained in 30-nm-thick film deposited at 660℃. Both of these values are sufficient for use in a 256 Mbit DRAM capacitor.
社団法人電子情報通信学会の論文
1994-03-25