Atomic-scale surface morphology of ultrathin thermal oxide formed on Si(100) surface

Fujimura, Masaaki; Inoue, Kouta; Nohira, Hiroshi; Hattori, Takeo

doi:10.1016/s0169-4332(00)00171-9

Cited by 18 publications

(8 citation statements)

References 11 publications

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“…The surface roughness increases with increasing oxidation time, but the interface roughness decreases with increasing oxidation time. This trend is similar to that reported for thermally oxidized SiO /Si systems [11], and suggests that the interface inherently tends to approach a perfect (100) plane by long-time oxidation. Hence, the nonuniformity of the oxide thickness can be minimized by using (100) wafer with minimized surface roughness, which is obtainable by removing an oxide layer after long-time oxidation, using a combination of heteroepitaxial growth, material-selective etching, etc.…”

Section: Discussionsupporting

confidence: 86%

Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

Iiyama

Kita

Ohta

et al. 2002

IEEE Trans. Electron Devices

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Abstract-A gate insulating layer with single nm-order thickness for suppressing gate leakage current is one of the key factors in extending downsizing limits, based upon the scaling rule, of field-effect-type transistors. We describe the fabrication and characterization of GaAs MISFETs with a nm-thin oxidized layer as the gate insulating layer, which is formed by an ultraviolet (UV) and ozone process. The UV and ozone process forms oxidized GaAs layers near the surface, which effectively suppress the reverse leakage current by several orders of magnitude. The fabricated GaAs MISFET can operate not only in the depletion mode, but also in the accumulation mode up to 3 V of the gate voltage for 8-nm-thick oxidized layer due to the current blocking effect of the oxidized layer. A current cutoff frequency of 6 GHz and a maximum oscillation frequency of 8 GHz are obtained for a GaAs MISFET with a 1-m-long gate length and 8-nm-thick oxidized layer.Index Terms-Compound semiconductors, GaAs, MISFET, selfalign, ultraviolet (UV) and ozone process.

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Section: Discussionsupporting

confidence: 86%

Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

Iiyama

Kita

Ohta

et al. 2002

IEEE Trans. Electron Devices

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“…However, the roughness values shown in Fig. 6 are comparable to those for ultra-thin SiO 2 layers formed by conventional dry O 2 thermal oxidation of Si [17][18][19], indicating that the SiO 2 layer obtained in this study has a sufficiently smooth surface and an interface in spite of the high oxidation rate and the relatively large thickness. It is considered that the roughness is related to the oxidation rate.…”

Section: Resultssupporting

confidence: 68%

Formation of silicon dioxide layers at low temperatures (150—400°C) by atmospheric pressure plasma oxidation of silicon

Kakiuchi¹,

Ohmi

Harada

et al. 2007

Science and Technology of Advanced Materials

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The formation of silicon dioxide (SiO 2 ) layers at low temperatures (150-400 1C) by atmospheric pressure plasma oxidation of Si(0 0 1) wafers have been studied using a gas mixture containing He and O 2 . A 150 MHz very high frequency (VHF) power supply was used to generate high-density atomic oxygen in the atmospheric pressure plasma. Oxidation rate, structure, and thickness and refractive index profiles of the oxidized layers were investigated by ellipsometry and infrared absorption spectroscopy. Atomic force microscopy was also employed to observe atomic-scale morphologies of the layer surface and wafer Si surface, after chemical removal of the oxidized layers. It was found that stoichiometric SiO 2 layers were obtained at higher oxidation rates than conventional dry O 2 thermal oxidation and radical oxidation processes, even at a very low substrate temperature of 150 1C. Although thickness variations were observed in the plasma region, the refractive index was independent of both substrate temperature and VHF power. In addition, the SiO 2 surface and SiO 2 /Si interface roughnesses were comparable to those obtained in conventional dry oxidation at high temperatures. r

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“…The compositional transition from Si to SiO 2 was studied by X-ray photoelectron spectroscopy (XPS) and was determined to have a truncated structure with one Si atomic layer of intermediate oxidation states such as Si 1þ , Si 2þ , and Si 3þ . [1][2][3] IR spectroscopy on thin SiO 2 films suggested a thin layer of intermediate oxides near the SiO 2 / Si interface, 4) which is consistent with the XPS results. On the other hand, the structural transition from bulk crystalline Si to amorphous SiO 2 requires a few molecular SiO 2 layers.…”

Section: Introductionsupporting

confidence: 83%

“…This reconfirms that a dense transition layer exists. [3][4][5] The XRR spectrum shows oscillation and the SR sample has a higher amplitude than the RTP one. The oscillation amplitude corresponds to the density difference in a film including the substrate.…”

Section: Transition Layermentioning

confidence: 99%

“…X-ray reflectivity (XRR) studies showed the existence of a dense transition layer of about 1 nm thick at the interface and an overlayer on it. [5][6][7] Studies of surface roughness by atomic force microscopy (AFM) 3) and of the energy level of the valence band by XPS 8) also suggested a transition layer of about 1 nm thick. We might say a structural transition layer about 1 nm thick exists, but we do not have sufficient information to build a clear image of the nanostructure of the density profile including a transition layer near the SiO 2 /Si interface.…”

Section: Introductionmentioning

confidence: 99%

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Density Profile of Thermal Oxide Thin Films on Si(100)

Odaka¹,

Kurokawa²,

Azuma³

et al. 2012

Jpn. J. Appl. Phys.

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We investigated the density profile of thermally grown SiO2 thin films on a Si(100) using X-ray reflectivity. Samples were grown at 750 and 1000 °C with a slow ramp process and at 1000 and 1100 °C with a rapid thermal process. A SiO2 thin film was reconfirmed to have a two-layer structure: a dense transition layer of about 1 nm and an overlayer. The density profile was affected by the ramp rate and the growth temperature. The SR samples had some complicated features in the overlayer such as an inversion accompanying a density jump at 750 °C or a dense part near the transition layer at 1000 °C. The transition layer maintained a constant density from 750 to 1000 °C. The RTP samples showed a simple two-layer structure with a smaller density than the SR ones. The density was classified into four discrete groups according to its value.

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Atomic-scale surface morphology of ultrathin thermal oxide formed on Si(100) surface

Cited by 18 publications

References 11 publications

Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

Formation of silicon dioxide layers at low temperatures (150—400°C) by atmospheric pressure plasma oxidation of silicon

Density Profile of Thermal Oxide Thin Films on Si(100)

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