Kinetic and Diffusional Aspects of the Dissolution of Si in HF Solutions

Meerakker, J. E. A. M. van den; Mellier, M.

doi:10.1149/1.1349879

Cited by 17 publications

(14 citation statements)

References 14 publications

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“…At low temperatures and HF concentrations, this current was not affected by the rotation rate. This behavior is identical to that of n-type Si under strong illumination [8]. It could be explained by assuming that at the peak an equilibrium exists between the anodic oxidation of Si to SiO 2 and the chemical dissolution of this oxide in HF.…”

Section: Methodssupporting

confidence: 54%

Anodic silicon etching; the formation of uniform arrays of macropores or nanowires

Meerakker

Elfrink

Weeda

et al. 2003

phys. stat. sol. (a)

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Macropore formation on p-type Si in the dark has been studied on 6-inch wafers in aqueous HF solution. More than 10 9 pores with a diameter of 2.5 µm and a depth of 100 µm are obtained in a single etch step. These pores can be used as a template for the fabrication of high-density MOS capacitors. If the current density is close to the characteristic peak for the anodic etching of Si in HF solutions, nanowires are obtained. The length of these wires can reach values up to 100 µm, while their width can be as small as 30 nm. This method is a suitable way to the high-volume production of nanowires.

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Section: Methodssupporting

confidence: 54%

Anodic silicon etching; the formation of uniform arrays of macropores or nanowires

Meerakker

Elfrink

Weeda

et al. 2003

phys. stat. sol. (a)

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“…Based on this mechanistic principle, the time needed for droplet formation is limited by the etching rate forming the hydrophobic sites. Higher DHF concentration results in faster etching kinetics, [34] and would therefore correspond to a shorter droplet formation time, as shown in Figure 1c. It should be noted that if the concentration of HF was too high (> 10 %), droplet formation was not observed, probably because of the fast etching and severe surface roughening of Si.…”

Section: Full Papermentioning

confidence: 96%

“…Figure 4b shows the formation of such a pore by applying a negative tip bias of 8 V above the oxide dot P. The oxide dot Q remains unaffected because it has not been subjected to further voltages. It is known that the dissolution of SiO 2 is a chemical reaction, rather than an electrochemical process, as formulated below: [34] SiO 2 …”

Section: Full Papermentioning

confidence: 99%

Microdroplet and Atomic Force Microscopy Probe Assisted Formation of Acidic Thin Layers for Silicon Nanostructuring

Xie

Chung

Sow

et al. 2007

Adv Funct Materials

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In this work, an aqueous acidic thin‐layer‐based strategy for fabricating nanostructures on silicon by using atomic force microscopy (AFM) nanolithography is presented. The approach involves the formation of microscale droplets via dilute hydrofluoride (DHF) etching, the conversion of the droplets to acidic thin layers by AFM‐probe scanning, and subsequent lithographic operations using a biased probe in the aqueous layers. By varying the concentration of the acidic DHF layers, the thin layers can facilitate the creation of both positive and negative patterns, such as oxide dots and Si pores, through anodic oxidation and dissolution. In particular, the anodic oxidation in the acidic media is associated with the field‐enhanced nonequilibrium dissociation of the weak electrolyte. The Si pore structure formation is related to the field‐assisted dissolution of anodic oxides and the Si substrate. The acidic‐layer‐based technique allows switching between different lithographic modes by changing the acidity of the DHF layers, and is complementary to bulk solution‐based and local meniscus‐based approaches in AFM nanolithography. In principle, this method can also be extended to other materials that have similar reactions with DHF.

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“…Si dissolution rate laws have been found previously for anodic oxidation of Si rotating disks by considering Si oxidation followed by dissolution of oxidized regions of the surface. 43 The rate of Si oxidation to Si 2+ increases exponentially with increasing potential 44…”

Section: E73mentioning

confidence: 99%

Copper Deposition onto Silicon by Galvanic Displacement: Effect of Silicon Dissolution Rate

daRosa

Maboudian

Iglesia

2008

J. Electrochem. Soc.

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The rates of Cu deposition onto rotating Si electrodes were measured to probe the effects of mass transfer, Cu 2+ reduction, and Si oxidation and dissolution on deposition dynamics. Cu deposition rates were proportional to CuSO 4 concentration and limited by Cu 2+ diffusion and subsequent reduction at high HF concentrations ͓͑HF͔/͓CuSO 4 ͔ Ͼ 20͒. In contrast, Si dissolution limited film growth at low HF concentrations ͓͑HF͔/͓CuSO 4 ͔ Ͻ 10͒, and HF 2 − was identified as the most active Si etchant. The observed effects of rotation rate indicate that mass transfer of Cu 2+ limits deposition rates, but mass transfer of HF does not. Open-circuit potential measurements and mixed-potential theory were used to develop a reaction-transport model that accurately predicts deposition rates over a broad range of Cu and HF concentrations. The structure of the films formed was probed by atomic force microscopy. The roughness of the Cu films decreased with increasing ͓HF͔/͓CuSO 4 ͔ ratios, as Si surfaces became less oxidized, and lateral connectivity between Cu nuclei increased.Galvanic displacement has been used for metal deposition on Si for applications including microelectromechanical system, 1,2 surface-enhanced Raman spectroscopy, 3-5 and catalysis. 6,7 Galvanic displacement offers the advantage of selective deposition because reduction of metal ions is coupled with oxidation and dissolution of the substrate. A schematic diagram of galvanic displacement of Cu onto Si is shown in Fig. 1, indicating the mass transfer and kinetic processes required for deposition. Fluoride species, HF in this case, must be added to dissolve oxidized Si and expose additional Si to continue galvanic displacement. Galvanic displacement occurs spontaneously when the depositing metal is more noble ͑easier to reduce͒ than both the substrate and hydrogen. Thus, Cu can be deposited by galvanic displacement because of its favorable reduction potential 8where NHE is the potential of the normal hydrogen electrode. Si is easily oxidized ͑Si 2+ /Si E 0 = −0.81 V 9 ͒, making it a suitable substrate for galvanic displacement. In this work, the concentrations of Cu 2+ and HF are varied to determine the effects of the oxidation and reduction half-reactions on Cu deposition rates and the structure Cu films. Several studies have examined the effects of Cu 2+ concentration on galvanic displacement rates. Deposition rates were found to be first-order in Cu 2+ concentration for deposition on substrates including Si, Fe, and Zn. [10][11][12][13][14] Less is known about the effect of HF concentration on deposition rates. Deposition rates increased with increasing HF concentration for deposition of Cu and Ag on Si, but few HF concentrations were studied, and the relationship between HF concentration and Cu deposition rates was not quantified. 10,15 In this work, we investigate the effect of Si dissolution on Cu deposition rates by systematically varying the HF concentration.In addition to the effects of formal HF concentration, the fluoride species responsible for Si...

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Kinetic and Diffusional Aspects of the Dissolution of Si in HF Solutions

Cited by 17 publications

References 14 publications

Anodic silicon etching; the formation of uniform arrays of macropores or nanowires

Anodic silicon etching; the formation of uniform arrays of macropores or nanowires

Microdroplet and Atomic Force Microscopy Probe Assisted Formation of Acidic Thin Layers for Silicon Nanostructuring

Copper Deposition onto Silicon by Galvanic Displacement: Effect of Silicon Dissolution Rate

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