Quantitative analysis of thermally induced desorption during halogen-etching of a silicon (111) surface

Shudo, K.; Kirimura, Tomoyuki; Tanaka, Yoshihito; Ishikawa, Tetsuya; Tanaka, Masatoshi

doi:10.1016/j.susc.2006.05.052

Cited by 5 publications

(7 citation statements)

References 29 publications

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“…The subsequent decline of R ax can be explained by retardation of reaction and, correspondingly, increased probability of SiCl 2 desorption from the surface. Extensive theoretical and experimental studies have indicated preferential removal of the surface Si atoms in the form of SiCl 2 . − The feasibility of SiCl 4 etching of SiNWs at 850 °C was also confirmed in our experiments when the hydrogen flow was turned off after the growth and SiNWs were kept in the SiCl 4 /N 2 atmosphere (data not shown). For example, after a 5 min exposure to SiCl 4 , the base diameters of SiNWs grown for 5 min at x SiCl 4 / x H 2 = 0.01/0.1 shrank from ca.…”

Section: Resultssupporting

confidence: 74%

Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure

2010

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Device applications of tapered Si nanowire (SiNW) arrays require reliable technological approaches for fabricating nanowires with controlled shape and orientation. In this study, we systematically explore effects of growth conditions on tapering of Si nanowires grown by chemical vapor deposition (CVD) at reduced pressure from SiCl(4) precursor. Tapering of SiNWs is governed by the interplay between the catalyzed vapor-liquid-solid (VLS) and uncatalyzed vapor-solid (VS) growth mechanisms. We found that the uncatalyzed Si deposition on NW sidewalls, defined by a radial growth rate, can be enhanced by lowering SiCl(4)/H(2) molar ratio, applying higher gas flow rate, or reducing growth pressure. Distinct dependences of the axial and radial growth rates on the process conditions were employed to produce SiNWs with a tapering degree (i.e., a ratio of the radial/axial growth rates) varying by almost 2 orders of magnitude. The results are explained by an interplay between the thermodynamic and kinetic effects on the axial (VLS) and radial (VS) growth rates. Established correlation between the SiCl(4)/H(2) molar ratio and vertical alignment of nanowires was used to develop a two-stage growth procedure for producing tapered SiNW arrays with a predominantly vertical orientation.

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Section: Resultssupporting

confidence: 74%

Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure

2010

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“…1). The desorption energies of SiCl 2 and SiCl decrease from 7.40-8.46 eV to 1.4-3.2 eV and 4.52-5.74 eV, respectively, compared with bared silicon atoms [26,[31][32][33][34][35][36]. This condition provides a favorable surface for the next step, which is photon irradiation.…”

Section: Photon-based Acsm Approachmentioning

confidence: 94%

“…1), and SiCl experiences difficulty in obtaining sufficient kinetic energy to overcome the potential barrier according to MGR model. Here, the Antoniewicz model can be used to explain the desorption of SiCl, in which the adsorbate is first excited to the ionized state by high-energy photons and then drops to the ground state [31] 3.2 eV [32] 2.4 eV [33] 2.2 eV [34] 1.65 eV [26] 1.4-2.9 eV [35] 5.74 eV [36] 5.4 eV [26] 4.52 eV [31] SiCl (Fig. 4).…”

Section: Description Of Models For Photon-induced Desorptionmentioning

confidence: 99%

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Wang

2021

Nanomanuf Metrol

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This paper presents a new approach for material removal on silicon at atomic and close-to-atomic scale assisted by photons. The corresponding mechanisms are also investigated. The proposed approach consists of two sequential steps: surface modification and photon irradiation. The back bonds of silicon atoms are first weakened by the chemisorption of chlorine and then broken by photon energy, leading to the desorption of chlorinated silicon. The mechanisms of photon-induced desorption of chlorinated silicon, i.e., SiCl2 and SiCl, are explained by two models: the Menzel–Gomer–Redhead (MGR) and Antoniewicz models. The desorption probability associated with the two models is numerically calculated by solving the Liouville–von Neumann equations for open quantum systems. The calculation accuracy is verified by comparison with the results in literatures in the case of the NO/Pt (111) system. The calculation method is then applied to the cases of SiCl2/Si and SiCl/Si systems. The results show that the value of desorption probability first increases dramatically and then saturates to a stable value within hundreds of femtoseconds after excitation. The desorption probability shows a super-linear dependence on the lifetime of excited states.

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“…Figure 2 shows a STM image observed at room temperature after heating the sample to 873 K for about 20 min. This treatment leads to desorption of most of the chlorine atoms on the surface [14,30]. In the image, obtained at room temperature, only one step is seen.…”

Section: Aligned Clusters On the Terracementioning

confidence: 99%

“…The kinetics of the etching process with chlorine, bromine and iodine has been widely studied in terms of the atomic structure [9,10], island/cluster formation [11] and reconstruction strain [12]. It is recognized that the reaction is qualitatively the same among these halogen species as regards the surface structure [13] although the desorption barriers of the silicon halides are different [14]. When halogen is adsorbed on a Si(111) surface, an unreconstructed 1 × 1 structure can stably exist [15], and reconstruction from 1 × 1 to 7 × 7 takes place at a lower temperature [13,16] than on a clean surface [17].…”

Section: Introductionmentioning

confidence: 99%

Regular arrangement of nanometre-scale clusters by surface strain on stabilized Cl/Si(111)

Shudo¹,

Koike²,

Owa³

et al. 2007

J. Phys.: Condens. Matter

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The dynamic processes during halogen etching at a Si(111) surface were observed at atomic resolution using a scanning tunnelling microscope (STM) at high temperature. It was found that after the thermal desorption of chlorine atoms, the metastable ‘1 × 1’ structure and the 7 × 7 structure coexisted at a relatively low temperature. The narrow strips of the metastable ‘1 × 1’ structure within the 7 × 7 structure tended to be straight, presumably because this minimizes the strain energy induced by the reconstruction. At the same time, silicon atoms diffusing on the surface appear to be trapped on the boundary strips, where nucleation occurs to form silicon clusters. After the sample had been cooled to room temperature, the silicon clusters were still regularly aligned. Our results indicate that the dynamics of the reconstruction from the ‘1 × 1’ to the 7 × 7 structure leads to the straightening of the boundary, resulting in the regular alignment of silicon clusters. The formation mechanism of the clusters appears to be related to the stabilization of the surface by halogen adsorption, because such a pattern was not formed upon thermal treatment of Si(111) without chlorine adsorption. The simple thermal treatment presented here may provide a new approach to the assembly of regular arrangements of nanometre-scale silicon clusters.

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Quantitative analysis of thermally induced desorption during halogen-etching of a silicon (111) surface

Cited by 5 publications

References 29 publications

Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure

Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Regular arrangement of nanometre-scale clusters by surface strain on stabilized Cl/Si(111)

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Quantitative analysis of thermally induced desorption during halogen-etching of a silicon (111) surface

Cited by 5 publications

References 29 publications

Tapering Control of Si Nanowires Grown from SiCl4 at Reduced Pressure

Tapering Control of Si Nanowires Grown from SiCl4 at Reduced Pressure

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

Regular arrangement of nanometre-scale clusters by surface strain on stabilized Cl/Si(111)

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Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure

Tapering Control of Si Nanowires Grown from SiCl₄ at Reduced Pressure