TiO[sub 2]∕Al[sub 2]O[sub 3]∕TiO[sub 2] Nanolaminated Thin Films for DRAM Capacitor Deposited by Plasma-Enhanced Atomic Layer Deposition

Abstract

TiO 2 /Al 2 O 3 /TiO 2 nanolaminated thin films investigated for the application of dynamic random access memory (DRAM) capacitor dielectrics. TiO 2 is a promising high-k material, but its leakage current property is poor. Al 2 O 3 nanolaminated film was inserted between two amorphous TiO 2 layers, and an Al 2 O 3 thickness greater than 10A effectively reduced the leakage current. When TiO 2 layers were crystallized to enhance the dielectric constant, a thicker Al 2 O 3 sublayer was required. As a result, anatase-TiO 2 (40 A)/Al 2 O 3 (12.5 A)/rutile-TiO 2 (40 A) nanolaminated film is suggested as an optimal structure that gives k = 44 (equivalent oxide thickness) with a leakage current of 6.46 X 10 -7 A/cm 2 at 1 MV/cm.