The electrical characteristics of metal–insulator–metal (MIM) capacitors consisting of a ZrO2/Al2O3/ZrO2 (ZAZ) dielectric film, a TiN bottom electrode (BE), and two different top electrodes (TEs; TiN and Ru) are examined. The enhanced property in the leakage current density versus equivalent oxide thickness (J–tox) plot is observed in the MIM structure with the Ru TE for the ZAZ film with specific film thickness of ≈4.6 nm. Especially, the J due to the electron injection from the TiN BE was significantly decreased for the Ru TE case compared to the TiN TE sample at 1–2 MV cm−1 electric field region. These extraordinary behaviors are found to have originated the change in the oxygen vacancy density in the ZAZ film, which induces Poole–Frenkel emission through the reaction with the active oxygen during the Ru TE fabrication process. The difference in nonlinearity of the capacitance–voltage (C–V) curve also indicates a different trap density at the interface of ZAZ and the TiN BE, suggesting a change in the oxygen vacancy density in the ZAZ film.

The atomic layer deposition process of SrTiO3 (STO) films at 230 °C was studied with Sr­(iPr3Cp)2 and Ti­(CpMe5)­(OMe)3 (Pr, Cp, and Me are propyl, cyclopentadienyl, and methyl groups, respectively) on Ru substrates. The growth behavior and properties of STO films grown at 230 °C were compared with those deposited at 370 °C. With the limited over-reaction of the Sr precursor during the initial growth stage at a lower temperature, the cation composition was more controllable, and the surface morphology after crystallization annealing at 650 °C had more uniform grains with fewer defects. Here, the excess reaction of the Sr precursor means the chemical-vapor-deposition-like growth of the SrO component mediated through the thermal decomposition of the adsorbed Sr precursor molecules. It was by the reaction of the Sr precursor with the oxygen supplied from the partly oxidized Ru substrate. The second STO was grown at 370 °C (main layer) on the annealed first STO layer (crystallized seed layer) to lead to the in situ crystallization of the main layer. Due to the improved microstructure of STO films induced by the seed layer deposited at 230 °C, the bulk dielectric constant of 167 was obtained for the main layer, which was higher than the value of 101 where the seed layer was deposited at 370 °C, even though the crystallization annealing condition of the seed layer and the deposition condition of the main layer were consistent. The seed layer grown at 230 °C, however, had a lower dielectric constant of only ∼49, whereas the high-temperature seed layer had a dielectric constant of ∼106. Therefore, the low-temperature seed layer posed a severe limitation in acquiring an advanced capacitor property with the involvement of a low-dielectric interfacial layer.

A metal–insulator–metal (MIM) capacitor consisting of TiN and ZrO2/Al2O3/TiO2 (ZAT) as electrodes and dielectric layer, respectively, is demonstrated for the development of next‐generation dynamic random access memory. The TiO2 layer deposited on ZrO2–Al2O3 exhibits a highly crystallized structure with an anatase phase and a dielectric constant of 40, resulting in a significant capacitance density enhancement compared with the conventional ZrO2/Al2O3/ZrO2 (ZAZ) film. The leakage current of the ZAT film can be controlled to a level comparable with that of the ZAZ film, and the carrier conduction mechanism is dominated by the thermionic emission mechanism. Consequently, a minimum equivalent oxide thickness scaling by ≈14% can be achieved by employing ZAT, compared with the conventional ZAZ.

SrTiO3 (STO) films are grown via atomic layer deposition at 370 °C with a two‐step growth method. A 5‐nm‐thick seed layer is first deposited and annealed via rapid thermal annealing (RTA) at temperatures ranging from 450 to 650 °C, and the main layer is subsequently grown on the annealed seed layer for in situ crystallization. When the RTA temperature is 500 °C or lower, the seed layer remains amorphous, and the main layer is also grown in the amorphous phase. At the 550 °C seed annealing temperature, the STO film is partially crystallized, and at the higher annealing temperature, the STO main layer is fully crystallized. The oxygen diffuses through the vertically aligned grain‐boundaries during the crystallized film growth, which induces the oxidation–reduction reaction of the underlying Ru substrate. This reaction causes a higher growth rate in the crystalline phase. The large growth rate difference between the amorphous and crystalline regions induces a severe roughening of the main layer. When RTA is done at 600 °C, the film is mostly crystallized, and the main layer becomes smooth again. Consequently, a 0.52 nm equivalent oxide thickness is achieved with the low leakage current of 2.5 × 10−8 A cm−2 at the 0.8 V applied bias.

Al is doped to a SrTiO3 (STO) thin film grown by atomic layer deposition (ALD) to decrease the leakage current. One ALD cycle of Al2O3 is processed either at the top or at the bottom of the STO films, and the electrical properties are compared with those of the undoped STO films. The ≈3.5 nm‐thick seed layer is first deposited and crystallized through rapid thermal annealing, and from 5 to 20 nm‐thick main layers are subsequently grown for in situ crystallization of the main layer. When an Al2O3 deposition cycle is inserted below the first seed layer, the crystallization of the STO films is disturbed, and the bulk dielectric constant degrades from 149 (undoped STO) to 71. When the Al2O3 deposition cycle is performed after the STO main layer growth, however, the dielectric constant degradation is minimized (120). In both cases, the leakage current decreases 20 times compared with the undoped STO case because of the conduction band offset increase. Consequently, the equivalent oxide thickness and physical oxide thickness decrease from 0.71 to 0.63 nm and from 10.3 to 8.6 nm, respectively, through Al doping on the top of the STO films with a sufficiently low leakage current (<10−7 A cm−2).