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Papers by Atsuyuki Fukano

Introduction Silicon industry is now paying attention to high-k and SiON dielectric materials as ... more Introduction Silicon industry is now paying attention to high-k and SiON dielectric materials as a candidate gate insulator beyond ultra-thin (<1nm) SiO2 film. The present limitations in ultra-thin SiO2 film are, however, defects in the Si-O interface which is a source of leakage current. In order to improve insulating performance, sub-oxide layer in the interface must be minimized in thickness. Our approach is to densify the SiO2 film to minimize defect density. There are several polymorphous for SiO2 with different packing (density); i.e. stishovite (4.35g/cm), coesite (2.93g/cm), quartz (2.6 ~ 2.65g/cm), tridymite (2.28 ~ 2.33g/cm) and cristobalite (2.32g/cm). High density SiO2 in an amorphous form is also known; i.e. lechatelierite (2.5 ~ 2.65g/cm). Densification of glassy silica is achieved by high pressure. Density of thermally oxidized SiO2 film on the silicon wafer is 2.14 ~ 2.23g/cm.[1] High density forms are expected to have less defects; e.g oxygen imperfection. Recent...

MRS Proceedings, 2002

The low-temperature growth of thin SiO2 layers for gate insulators in very large-scale integrated... more The low-temperature growth of thin SiO2 layers for gate insulators in very large-scale integrated (VLSI) circuits is becoming an urgent topic of silicon technology. In contrast, to conventional thermal oxidization processes (T>900°C), ultraviolet (UV) photo-oxidation of silicon technology is a promising approach for low-temperature growth of silicon dioxide thin films. We have grown silicon dioxide thin films at low temperature (T<500 °C) using an excimer lamp with various wavelengths and evaluated the quality of thin SiO2 layers as well as the SiO2–Si interface. We found that the SiO2 layers (t<5 nm) grown by UV photo-oxidation show significant differences in physical properties, such as density profile, from those of thermal oxidization, i.e., the higher average density 2.23 g/cm3 and more constant distribution, making the SiO2–Si interface region, so-called “transition layer” less eminent. Superior characteristics of ultra-thin SiO2 layer grown by UV photo-oxidation are ...

Japanese Journal of Applied Physics, 2005

Journal of Applied Physics, 2003

Highly insulating ultrathin SiO2 films (<5 nm) were grown by means of vacuum ultraviolet photo... more Highly insulating ultrathin SiO2 films (<5 nm) were grown by means of vacuum ultraviolet photooxidation, by use of 126, 172, and 222 nm wavelength photons generated by excimer lamps. The ultrathin silicon dioxide films were grown onto the Si(001) substrate, at low temperature (<500 °C). We found that the densities of photooxidized SiO2 films were 13%–35% higher than that of thermally oxidized SiO2 film. The density profile was obtained by x-ray reflectivity and showed a remarkable decrease in the SiOx (suboxide) layer thickness at the SiO2−Si interface, in comparison with thermally oxidized conventional oxides. The Si 2p photoelectron spectrum confirmed that the SiOx layer was negligibly thin. High insulating performance of the SiO2 film was demonstrated.

Kokuritsu Kikan Genshiryoku Shiken Kenkyu Seika Hokoku-Sho, 2004

Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy, 1996

AIP Conference Proceedings, 2004

Superior insulating performance is found for dense silicon dioxide ultra‐thin films (∼3 nm) grown... more Superior insulating performance is found for dense silicon dioxide ultra‐thin films (∼3 nm) grown by UV photo‐oxidation of silicon. Density profile obtained by glazing incidence x‐ray reflectivity shows that the high density (2.32 g/cm3) SiO2 is formed on Si(100) surface at much lower temperature (<450 °C) than thermal oxidation, using 126 nm photons. The sharp and flat interface within 1–2 monolayers is revealed by high resolution transmission electron microscopy. The film density is strongly dependent on wavelength around 172–126 nm, suggesting that the specific excited species of oxygen is involved in the growth mechanism. Unique properties of photo‐oxidized silicon dioxide are related to the modified Si‐O network structure and ring statistics.

The Journal of Physical Chemistry C, 2009

The Journal of Physical Chemistry C, 2010

... nanocrystals. Foos et al.(11) and Jose et al.(17) reported that the addition of amine to the ... more ... nanocrystals. Foos et al.(11) and Jose et al.(17) reported that the addition of amine to the TOPO coordinating solvent delayed the initial nucleation of the CdSe particles as compared with the TOPO-alone synthesis, while Pradhan et al. ...

Surface Science, 1990

ABSTRACT

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003

Journal of the Physical Society of Japan, 1988

Journal of Synchrotron Radiation, 2006

Introduction Silicon industry is now paying attention to high-k and SiON dielectric materials as ... more Introduction Silicon industry is now paying attention to high-k and SiON dielectric materials as a candidate gate insulator beyond ultra-thin (<1nm) SiO2 film. The present limitations in ultra-thin SiO2 film are, however, defects in the Si-O interface which is a source of leakage current. In order to improve insulating performance, sub-oxide layer in the interface must be minimized in thickness. Our approach is to densify the SiO2 film to minimize defect density. There are several polymorphous for SiO2 with different packing (density); i.e. stishovite (4.35g/cm), coesite (2.93g/cm), quartz (2.6 ~ 2.65g/cm), tridymite (2.28 ~ 2.33g/cm) and cristobalite (2.32g/cm). High density SiO2 in an amorphous form is also known; i.e. lechatelierite (2.5 ~ 2.65g/cm). Densification of glassy silica is achieved by high pressure. Density of thermally oxidized SiO2 film on the silicon wafer is 2.14 ~ 2.23g/cm.[1] High density forms are expected to have less defects; e.g oxygen imperfection. Recent...

MRS Proceedings, 2002

The low-temperature growth of thin SiO2 layers for gate insulators in very large-scale integrated... more The low-temperature growth of thin SiO2 layers for gate insulators in very large-scale integrated (VLSI) circuits is becoming an urgent topic of silicon technology. In contrast, to conventional thermal oxidization processes (T>900°C), ultraviolet (UV) photo-oxidation of silicon technology is a promising approach for low-temperature growth of silicon dioxide thin films. We have grown silicon dioxide thin films at low temperature (T<500 °C) using an excimer lamp with various wavelengths and evaluated the quality of thin SiO2 layers as well as the SiO2–Si interface. We found that the SiO2 layers (t<5 nm) grown by UV photo-oxidation show significant differences in physical properties, such as density profile, from those of thermal oxidization, i.e., the higher average density 2.23 g/cm3 and more constant distribution, making the SiO2–Si interface region, so-called “transition layer” less eminent. Superior characteristics of ultra-thin SiO2 layer grown by UV photo-oxidation are ...

Japanese Journal of Applied Physics, 2005

Journal of Applied Physics, 2003

Highly insulating ultrathin SiO2 films (<5 nm) were grown by means of vacuum ultraviolet photo... more Highly insulating ultrathin SiO2 films (<5 nm) were grown by means of vacuum ultraviolet photooxidation, by use of 126, 172, and 222 nm wavelength photons generated by excimer lamps. The ultrathin silicon dioxide films were grown onto the Si(001) substrate, at low temperature (<500 °C). We found that the densities of photooxidized SiO2 films were 13%–35% higher than that of thermally oxidized SiO2 film. The density profile was obtained by x-ray reflectivity and showed a remarkable decrease in the SiOx (suboxide) layer thickness at the SiO2−Si interface, in comparison with thermally oxidized conventional oxides. The Si 2p photoelectron spectrum confirmed that the SiOx layer was negligibly thin. High insulating performance of the SiO2 film was demonstrated.

Kokuritsu Kikan Genshiryoku Shiken Kenkyu Seika Hokoku-Sho, 2004

Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy, 1996

AIP Conference Proceedings, 2004

Superior insulating performance is found for dense silicon dioxide ultra‐thin films (∼3 nm) grown... more Superior insulating performance is found for dense silicon dioxide ultra‐thin films (∼3 nm) grown by UV photo‐oxidation of silicon. Density profile obtained by glazing incidence x‐ray reflectivity shows that the high density (2.32 g/cm3) SiO2 is formed on Si(100) surface at much lower temperature (<450 °C) than thermal oxidation, using 126 nm photons. The sharp and flat interface within 1–2 monolayers is revealed by high resolution transmission electron microscopy. The film density is strongly dependent on wavelength around 172–126 nm, suggesting that the specific excited species of oxygen is involved in the growth mechanism. Unique properties of photo‐oxidized silicon dioxide are related to the modified Si‐O network structure and ring statistics.

The Journal of Physical Chemistry C, 2009

The Journal of Physical Chemistry C, 2010

... nanocrystals. Foos et al.(11) and Jose et al.(17) reported that the addition of amine to the ... more ... nanocrystals. Foos et al.(11) and Jose et al.(17) reported that the addition of amine to the TOPO coordinating solvent delayed the initial nucleation of the CdSe particles as compared with the TOPO-alone synthesis, while Pradhan et al. ...

Surface Science, 1990

ABSTRACT

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003

Journal of the Physical Society of Japan, 1988

Journal of Synchrotron Radiation, 2006