| 研究実績の概要 |
I proposed to employ a novel deposition process, supercritical fluid deposition (SCFD) of conformal TiO2, for applications on 3D memory device due to its conformal coverage on high aspect ratio (AR) features.SCFD involves the thermal decomposition of organic compounds (precursors) in the liquid-gas-like supercritical CO2 (scCO2), and is able to achieve conformal deposition with high growth rate on high aspect ratio features. SCFD has been employed for extremely conformal TiO2 deposition on 100 aspect ratio (AR) features with relatively high deposition rate of ~4nm/min, while conventional CVD-TiO2 has poor conformality on 3D structure and conformal ALD-TiO2 has low growth rate of < 0.5 nm/min.
In this project, considering that TiO2 is regarded as dielectrics for capacitor in memory as well as a photocatalyst (anatase phase) for water splitting, the self-developed conformal SCFD-TiO2 process was applied for 3D-capacitor in DRAM. Both 2D and 3D capacitors with RuO2/TiO2/RuO2 configuration were fabricated successfully. I-V and C-V measurement were conducted for SCFD-TiO2 on planar substrate, which had the leakage density of 10-6 A/cm2, breakdown voltage of 0.6 MV/cm, and dielectric constant of ~70 were achieved. These values are comparable to those samples prepared by conventional CVD methods. With the support of JSPS, our self-developed TiO2-SCFD has demonstrated its feasibility on 3D memory devices, and its application as water splitting photocatalyst is explored preliminary as well.
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