On the potential-dependent etching of Si(111) in aqueous NH4F solution

Houbertz, R.; Memmert, U.; Behm, R. J.

doi:10.1016/s0039-6028(97)00669-9

Cited by 23 publications

(36 citation statements)

References 31 publications

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“…Sizes and shapes of the triangular pits in the topmost layer strongly depend on the pH of etching solutions. Recently, Houbertz et al 12 have reported the potential-dependent etching of Si(111) in 40% NH 4 F solution, in which the morphologies of Si(111) surfaces at anodic, OCP, and cathodic potentials were visualized. These experiments revealed pronounced effects of the sample potential on the anisotropy of etch process and etch rates by ex situ STM.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Hydrides on Hydrogen-Terminated Silicon (111)−(1×1) Surface

Bok

Pan

et al. 1999

J. Phys. Chem. B

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X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometer (SSIMS) have been applied to characterize Si(111) surface treated with 40% NH4F solution. As-treated Si(111) surface is predominately terminated with monohydrides and free of contamination. The dynamics of etching process on ultra-clean atomically flat hydrogen-terminated Si(111) surface in 40% NH4F solution has been examined at various potentials including the open circuit potential (OCP) by using in situ electrochemical scanning tunneling microscopy (ECSTM). Two distinct mechanisms are observed: (1) dihydride terminated step silicon atoms are dissolved much faster than the defect-free monohydride terminated ones; (2) dihydrides in the corner of {110} zigzag enclosed characteristic triangular pits lead to fast erosion of silicon atoms. Our results explain dynamic mechanics in formation of triangular pits on atomically flat silicon (111) surface in solution.

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Section: Introductionmentioning

confidence: 99%

Dynamics of Hydrides on Hydrogen-Terminated Silicon (111)−(1×1) Surface

Bok

Pan

et al. 1999

J. Phys. Chem. B

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“…The height variation in the image shows the thickness of silicon oxide layer on silicon surfaces in which the heights of round silicon oxide range from 5 Å to 25 Å, which agrees very well with the reported thickness of silicon oxide layers. 8,20 After the etching of the Si(111) surface for 800 s, the surface morphology was so changed (Fig. 3b).…”

Section: Methodsmentioning

confidence: 99%

“…The typical feature of this surface is the perfect monohydrogen terminated terrace with about 3.1 bilayer step, which agrees well with the reported data. 8,13,15,20 It has been known that pit free surface of the Si(111)-H is obtained in oxygen free 40% NH4F solution. 19 However, in this image, a few triangular pits are present that attributes to the pH difference with 40% NH4F solution.…”

Section: Methodsmentioning

confidence: 99%

“…7 More detailed results of the preparation of atomically flat Si(111)-H surface can be seen in Behm's work in which the appearance of Si(111) surface investigated by ex situ STM was drastically changed with immersion time in 40% NH 4 F solution. 8 As the immersion time increased, the islands and pits disappeared, and the flat terraces became wider. This is attributed to the step flow reaction of the Si(111)-H surface.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of Atomically Flat Si(111)-H Surfaces in Aqueous Ammonium Fluoride Solutions Investigated by Using Electrochemical, In Situ EC-STM and ATR-FTIR Spectroscopic Methods

2004

Bulletin of the Korean Chemical Society

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Electrochemical, in situ electrochemical scanning tunneling microscope (EC-STM), and attenuated total reflectance-FTIR (ATR-FTIR) spectroscopic methods were employed to investigate the preparation of atomically flat Si(111)-H surface in ammonium fluoride solutions. Electrochemical properties of atomically flat Si(111)-H surface were characterized by anodic oxidation and cathodic hydrogen evolution with the open circuit potential (OCP) of ca. −0.4 V in concentrated ammonium fluoride solutions. As soon as the natural oxide-covered Si(111) electrode was immersed in fluoride solutions, OCP quickly shifted to near −1 V, which was more negative than the flat band potential of silicon surface, indicating that the surface silicon oxide had to be dissolved into the solution. OCP changed to become less negative as the oxide layer was being removed from the silicon surface. In situ EC-STM data showed that the surface was changed from the initial oxidecovered silicon to atomically rough hydrogen-terminated surface and then to atomically flat hydrogenterminated surface as the OCP moved toward less negative potentials. The atomically flat Si(111)-H structure was confirmed by in situ EC-STM and ATR-FTIR data. The dependence of atomically flat Si(111)-H terrace on mis-cut angle was investigated by STM, and the results agreed with those anticipated by calculation. Further, the stability of Si(111)-H was checked by STM in ambient laboratory conditions.

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“…This is known to leave the Si surface in a hydrophobic state, where the dangling bonds are saturated by mono-, di-and tri-hydrides, dependent on the surface orientation [19]. The ORMOCER solutions were deposited by spin coating (Karl Suss RC8, closed) including a prespin rinsing step of propylacetate.…”

Section: B Solution and Sample Preparationmentioning

confidence: 99%

Preventing of Dewetting Effects for Inorganic-Organic Hybrid Polymers Applied in Sequentially Buildup (SBU) Technology Without Surface Pretreatments

Uhlig

Domann

Houbertz

et al. 2006

IEEE Trans. Electron. Packag. Manufact.

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Upon processing waveguide structures by using the ORMOCER materials ORMOCORE as core material, and a mixture of ORMOCORE and ORMOCER-III (refractive index tuning agent) as cladding material, dewetting effects of the core layer from the cladding layer were observed. A similar phenomenon was observed for a mixture of ORMOCORE and ORMOCLAD which was used as comparative refractive index tuning material. In order to use these material combinations for large-area panel (LAP) processing, a pretreatment or activation of surfaces is necessary but hard to realize. However, the addition of small amounts of ORMOCER-III or ORMOCLAD, respectively, to the core layer material, prevented the dewetting phenomenon. The objective of this, however, is to minimize the content of refractive index tuning agent in the core layer by retaining a good wetting behavior during multilayer processing. Wet film stability tests and contact angle measurements of these ORMOCER systems in various compositions on another ORMOCER surface of a specific cladding material composition were performed on a hotplate. Furthermore, contact angles of droplets formed by deionized water, formamide, and di-iodomethane on cured surfaces of these ORMOCER systems in a wide range of compositions were characterized, and surface tensions were calculated. By adding 0.1 wt% of ORMOCER-III or 5 wt% ORMOCLAD, respectively, to the pure ORMOCORE solution, the dewetting phenomenon was eliminated, while simultaneously the refractive index was affected only to a minor degree and no changes in the optical loss could be detected. It was shown that by adding ORMOCER-III or ORMOCLAD to pure ORMOCORE, the surface tension of the compound system was reduced. In comparison to silanization or gasplasma treatment to overcome dewetting effects in microelectronics multilayer processing, the investigated mixing method eliminates process steps and thus costs, and opens new process routes for LAP processing.Index Terms-Alternative process route, contact angle measurement, dewetting, heterogeneous multilayer structure, large-area panel processing, ORMOCER, sequentially buildup unit (SBU), surface tension.

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On the potential-dependent etching of Si(111) in aqueous NH4F solution

Cited by 23 publications

References 31 publications

Dynamics of Hydrides on Hydrogen-Terminated Silicon (111)−(1×1) Surface

Dynamics of Hydrides on Hydrogen-Terminated Silicon (111)−(1×1) Surface

Preparation of Atomically Flat Si(111)-H Surfaces in Aqueous Ammonium Fluoride Solutions Investigated by Using Electrochemical, In Situ EC-STM and ATR-FTIR Spectroscopic Methods

Preventing of Dewetting Effects for Inorganic-Organic Hybrid Polymers Applied in Sequentially Buildup (SBU) Technology Without Surface Pretreatments

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