2015 Fiscal Year Annual Research Report
超臨界流体堆積法を用いたコンフォーマル酸化チタンのメモリや光触媒応用
| Project/Area Number |
15J09484
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| Research Institution | The University of Tokyo |
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Principal Investigator |
チョウ ユウ 東京大学, 工学系研究科, 特別研究員(DC2)
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| Project Period (FY) |
2015-04-24 – 2017-03-31
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| Keywords | Supercritical fluid / TiO2 / Crystalline / Dielectrics / 3D capacitor / Photocatalyst / Water splitting |
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| Outline of Annual Research Achievements |
Conformal TiO2 deposition for 3D memory device and water splitting photocatalyst [almost on schedule]
I proposed to employ a novel deposition process, supercritical fluid deposition (SCFD) of conformal TiO2, for applications on 3D memory device and water splitting, as both of which require 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. In my previous study, 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 (rutile phase) for capacitor in memory as well as a photocatalyst (anatase phase) for water splitting, the self-developed conformal SCFD-TiO2 process will be applied for 3D-capacitor in DRAM with and photocatalyst in water splitting.
Last year, the crystalline behavior of SCFD-TiO2 was studied by annealing first. Then electric properties of rutile TiO2 was measured for application on memory devices.Currently TiO2 3D-capacitor making is in progress. On the other hand, during 3-month oversea research, water splitting cells using TiO2 nano-wire were fabricated and characterized as trial experiments. I think the project is almost progresses on schedule.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
[First year]
1. Crystalline study of SCFD-TiO2[done]:(1) Post-annealing using planar; (2) Both anatase and rutile phases, and the phase change point should be investigated; (3) Optimization of post-annealing and deposition into one process
2. Investigation of SCFD-rutile-TiO2 for 3D memory[almost done, *strategy modified]: (1) Planar capacitor to check electric property of rutile-TiO2 first; (2)Conformal rutile TiO2 on high aspect ratio trenches; (3) *Fabrication of 3D capacitors combining SCFD-Cu and SCFD-TiO2 --> Cu is replaced by SCFD-RuO2, which has higher work function and is able to prevent leakage;(4) Electric property study for SCFD-fabricated 3D capacitors --> in progress
[Second year]
3. Investigation of SCFD-anatase-TiO2 for water splitting photocatalyst[fundamental study has done]; (1) Photocatalyst property of planar SCFD-anatase-TiO2--> in plan; (2) Conformal anatase TiO2 coating on Si pillar arrays with large surface area --> in plan; (3) Fabrication of water splitting cell --> Studied and fabricated TiO2 water-splitting cell during 3-month stay in the university of Alabama (U.S.) as visit scholar; (4) Measurement of solar energy conversion rate --> Studied and measured water-splitting efficiency as visit scholar to U.S.
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| Strategy for Future Research Activity |
In this year, I will first focus on finishing the 3D capacitor making by SCFD-TiO2, and then turn to characterization of photocatalyst property of SCFD. Though I have gained some experience on water-splitting cell making, there are still many challenges being expected. For example, which 3D structure is beneficial to efficiently convert solar energy (TiO2 on porous structure or Si pillar or other high AR structure), how to setup apparatus of water-splitting test in my own lab (or using test apparatus of other lab), and so on. If I can overcome all these issues with the support of JSPS, I could be proud to say that our self-developed TiO2-SCFD is more than a promising technique, and whose feasibility on both 3D memory devices and water splitting photocatalyst is confirmed experimentally.
[Plan of Second year]
1.Investigation of SCFD-rutile-TiO2 for 3D memory: (1) Electric property study for SCFD-fabricated 3D capacitors.
2. Investigation of SCFD-anatase-TiO2 for water splitting photocatalyst:(1) Photocatalyst property of planar SCFD-anatase-TiO2; (2) Conformal anatase TiO2 coating on Si pillar arrays with large surface area; (3) Fabrication of water splitting cell; (4) Measurement of solar energy conversion rate.
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Research Products
(3 results)
