Nanometer-scale Si selective epitaxial growth on Si(001) surfaces using the thermal decomposition of ultrathin oxide films

Fujita, Ken; Watanabe, Heiji

doi:10.1063/1.119065

Cited by 50 publications

(23 citation statements)

References 15 publications

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“…After oxygen exposure, the ͑2 3 1͒ reflection high-energy electron diffraction (RHEED) pattern disappeared and only ͑1 3 1͒ spots from the substrate remained. Also, in our previous scanning tunneling microscopy study, no ordered structure was recognized on the surface [16]. Note that the contrast of the initial ͑1 3 2͒ and ͑2 3 1͒ terraces was reversed in each oxidation step, 0031-9007͞98͞80(2)͞345(4)$15.00…”

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confidence: 94%

Kinetics of Initial Layer-by-Layer Oxidation of Si(001) Surfaces

Watanabe¹,

Kato²,

Uda³

et al. 1998

Phys. Rev. Lett.

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Layer-by-layer oxidation of Si(001) surfaces has been studied by scanning reflection electron microscopy (SREM). The oxidation kinetics of the top and second layers were independently investigated from the change in oxygen Auger peak intensity calibrated from the SREM observation. A barrierless oxidation of the first subsurface layer, as well as oxygen chemisorption onto the top layer, occurs at room temperature. The energy barrier of the second-layer oxidation was found to be 0.3 eV. The initial oxidation kinetics are discussed based on first-principles calculations.[S0031-9007(97)04959-4] PACS numbers: 81.65. Mq, Oxidation of Si surfaces is important for technological application of electronic devices [1][2][3]. Although many kinds of surface analyses have been used to study oxygen adsorption kinetics onto Si surfaces [4][5][6][7][8][9], the oxidation kinetics of subsurface layers, which determine oxide film growth, have not been studied in detail. This is because of the difficulty of experimentally and independently analyzing the oxidation processes of specific subsurface layers. In this Letter we used scanning reflection electron microscopy (SREM [10]) combined with Auger electron and x-ray photoelectron spectroscopy (AES and XPS) to investigate the initial oxidation of Si(001) surfaces. Our combined analysis has a great advantage for observing layer-by-layer oxidation of subsurface layers, as well as the step and terrace configurations buried with oxide layers. We report, for the first time, reaction barriers of the uppermost and second layer oxidations, and discuss our experimental results based on first-principles calculations.Our experiments were carried out using an ultrahighvacuum surface analysis system that performs SREM, AES, and XPS [11]. This system is equipped with a thermal field emission electron gun, a precision energy analyzer (a spherical capacitor analyzer), and a conventional x-ray source (Mg Ka excitation). A 30-keV electron beam with a 2-nm diameter was used for the SREM with a low incident angle of about 2 ± to the surface. The AES measurement could be performed simultaneously by using the electron gun for SREM at an incident angle and detection angle of about 2 ± and 73 ± to the sample surface, respectively. The XPS was performed with a 60 ± takeoff angle with respect to the normal to the surface. A Si(001)-͑2 3 1͒ surface was prepared by flash heating with a direct current. Oxidation of the surfaces was carried out by introducing molecular oxygen into the analysis chamber. Since the electron gun and the energy analyzer were independently evacuated, the AES measurement could be performed under oxygen pressure on the order of 10 26 Torr.As we previously reported, since SREM images of SiO 2 ͞Si systems are obtained by recording the intensity change in reflection spots from a crystal Si substrate covered with an amorphous oxide layer, the interfacial structure can be observed without the need to remove the SiO 2 overlayer [12][13][14]. Figures 1(a)-1(d) show SREM images of Si(001) surfaces...

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mentioning

confidence: 94%

Kinetics of Initial Layer-by-Layer Oxidation of Si(001) Surfaces

Watanabe¹,

Kato²,

Uda³

et al. 1998

Phys. Rev. Lett.

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288

146

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“…[2][3][4]9 Recently, we have shown that the formation and extension of voids can be observed dynamically by high-temperature scanning tunneling microscopy ͑STM͒. 10,11 These studies revealed that surface roughening during void formation is caused by the etching of void bottoms which supplies the Si atoms necessary for the oxide decomposition. A typical void depth is 0.3-0.5 nm when the oxide thickness is 0.3 nm, but the surface shows pronounced roughness when oxide layers are about 1 nm thick.…”

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confidence: 99%

Scanning tunneling microscopy study on void formation by thermal decomposition of thin oxide layers on stepped Si surfaces

Fujita¹,

Watanabe²

1998

Journal of Applied Physics

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We investigate void formation by thermal decomposition of thin oxide layers on stepped Si(001) and Si(111) surfaces by using high-temperature scanning tunneling microscopy. We have found that the surface roughening during void formation on stepped Si surfaces is less than that on on-axis Si surfaces. The Si atoms necessary for oxide decomposition are supplied from step edges on the stepped surface rather than by hole nucleation.

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“…The oxide thickness was estimated from Si 2 p corelevel spectra. 12 As we previously reported, even though SiO 2 films are a typical insulator, stable STM images of the oxide surface can be acquired by increasing the sample bias to ϩ5 V. 9,10,12 In this study, we used a Pt-Ir tip and all STM images were obtained at a ϩ5 V sample bias with a 0.5 nA constant tunneling current. Figure 1 shows an STM image of a 1-nm-thick SiO 2 film grown on a Si͑111͒ substrate.…”

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Observation and creation of current leakage sites in ultrathin silicon dioxide films using scanning tunneling microscopy

Watanabe¹,

Fujita²

1998

Applied Physics Letters

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We used scanning tunneling microscopy (STM) to investigate the local leakage current through ultrathin silicon dioxide (SiO2) films grown on Si substrates. Individual leakage sites, which were created by hot-electron injection from the STM tip under a high sample bias of +10 V, were identified from the local change in surface conductivity due to defect creation in the oxide films. When we reversed the stressing polarity (using a negative sample bias) no leakage sites were created in the oxide film.

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Nanometer-scale Si selective epitaxial growth on Si(001) surfaces using the thermal decomposition of ultrathin oxide films

Abstract: Reduction of sidewall defect induced leakage currents by the use of nitrided field oxides in silicon selective epitaxial growth isolation for advanced ultralarge scale integration

Cited by 50 publications

References 15 publications

Kinetics of Initial Layer-by-Layer Oxidation of Si(001) Surfaces

Kinetics of Initial Layer-by-Layer Oxidation of Si(001) Surfaces

Scanning tunneling microscopy study on void formation by thermal decomposition of thin oxide layers on stepped Si surfaces

Observation and creation of current leakage sites in ultrathin silicon dioxide films using scanning tunneling microscopy

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