Dae Seon Kwon1,Kun Hee Ye1,2,In Soo Lee1,Junil Lim1,Haengha Seo1,Tae Kyun Kim1,Heewon Paik1,Jonghoon Shin1,Jung-Hae Choi2,Cheol Seong Hwang1
Seoul National University1,Korea Institute of Science and Technology2
Dae Seon Kwon1,Kun Hee Ye1,2,In Soo Lee1,Junil Lim1,Haengha Seo1,Tae Kyun Kim1,Heewon Paik1,Jonghoon Shin1,Jung-Hae Choi2,Cheol Seong Hwang1
Seoul National University1,Korea Institute of Science and Technology2
The locally hetero-epitaxial growth and interfacial properties of atomic layer deposited (ALD) Al-doped TiO<sub>2</sub> (ATO) and Hf<span style="font-size:10.8333px">O<sub>2</sub></span> dielectric films were investigated with the Hf<span style="font-size:10.8333px">O<sub>2</sub></span>/ATO/Ru structure. The locally hetero-epitaxial growth of the ATO films on the Ru substrate could be divided into two stages: the first stage was highly affected by the Ru (and Ru<span style="font-size:10.8333px">O<sub>2</sub></span>) substrate and the second stage was by the ATO itself once the ATO fully covered the Ru substrate. The physicochemical properties of the films at each stage were investigated, supported by computational data, and local lattice-matched growth mechanisms were suggested. At a low thickness (<~4 nm) of the ATO film, the coherent structure of the rutile ATO with <i>in-situ</i> formed-rutile Ru<span style="font-size:10.8333px">O<sub>2</sub></span> was more stable. However, at a higher thickness (>~4 nm), the incoherent structure of the rutile ATO was more stable, leading to the evolution of the new grains with random crystalline orientations. Subsequently, these structural differences in the rutile ATO highly affected the growth of the upper Hf<span style="font-size:10.8333px">O<sub>2</sub></span> films. As a result, the evolution of the monoclinic phase of the Hf<span style="font-size:10.8333px">O<sub>2</sub></span> film was suppressed on the ATO film with the appropriate thickness (~2.5 nm). Also, the surface morphology and the interfacial chemical bonding nature of the Hf<span style="font-size:10.8333px">O<sub>2</sub></span>/ATO films depended on the crystalline structure of the rutile ATO films. Finally, the electrical properties of the Pt/Hf<span style="font-size:10.8333px">O<sub>2</sub></span>/ATO/Ru structured capacitors were obtained. Minimum equivalent oxide thickness (EOT) and physical oxide thickness (POT) values were 0.61 nm and 4.28 nm, respectively, while still satisfying the specification of the dynamic random-access memory (DRAM) leakage current density (<10<sup><span style="font-size:10.8333px">-7</span></sup> A/cm<sup>2</sup> at a capacitor voltage of 0.8 V).