ZrO₂/Al₂O₃/ZrO₂ layers have been commercially employed for a long time as the dielectric materials of dynamic random access memory (DRAM) capacitors. However, the scaling limit of capacitors due to the insufficiently high permittivity of ZrO₂ required novel materials. SrTiO₃ (STO) has been considered as a
promising candidate for the dielectric materials in next-generation DRAM capacitor applications due to the high dielectric constant (~150 in the thin-film state) and acceptable energy bandgap (~3.2 eV).

In addition to the employment of SrTiO₃ dielectrics, an extreme three-dimensional structure (aspect ratio ~100:1) should be adopted to achieve a high enough capacitance for normal DRAM operation. Therefore, atomic layer deposition (ALD) should be employed for the utilization of its merit, exceptional conformality by the self-limited surface reaction.