Atomic Layer Deposition of SrTiO3 Thin Films with Highly Enhanced Growth Rate for Ultrahigh Density Capacitors

Abstract

The ever-shrinking dimensions of dynamic random access memory (DRAM) require a high quality dielectric film for capacitors with a sufficiently high growth-per-cycle (GPC) by atomic layer deposition (ALD). SrTiO3 (STO) films are considered to be the appropriate dielectric films for DRAMs with the design rule of ∼20 nm, and previous studies showed that STO films grown by ALD have promising electrical performance. However, the ALD of STO films still suffers from much too slow GPC to be used in mass-production. Here, we accomplished a mass-production compatible ALD process of STO films using Ti(O-iPr)2(tmhd)2 as a Ti-precursor for TiO2 layers and Sr(iPr3Cp)2 as a Sr-precursor for SrO layers. O3 and H2O were used as the oxygen sources for the TiO2 and SrO layers, respectively. A highly improved GPC of 0.107 nm/unit-cycle (0.428 nm/supercycle) for stoichiometric STO films was obtained at a deposition temperature of 370 °C, which is ∼7 times higher than previously reported. The origin of such high GPC values in ...