Etching Silicon with HF-H₂O₂-Based Mixtures: Reactivity Studies and Surface Investigations

Abstract

In semiconductor and photovoltaic industries numerous process steps deal with etching and silicon surface modification. The present study focuses on the reactivity of HF-H2O2-based mixtures toward silicon surfaces in a wide range of concentrations. The generally very moderate reactivity is investigated regarding kinetic aspects and the silicon dissolution reactions. The activation energy of silicon dissolution in HF-H2O2 mixtures is determined to be ∼50 kJ/mol, which supports a surface reaction controlled mechanism. This interpretation is checked by oxidation experiments of Si surfaces with HF-free H2O2 solutions. Resulting silicon surfaces were characterized by means of diffuse reflection Fourier transform infrared spectroscopy and photoelectron spectroscopy. Surface properties give hints for an “electrochemical” silicon oxidation. Furthermore, the oxidation behavior of different H2O2 solutions is compared to that of HNO3 solutions. All results suggest kinetically limited silicon dissolution in HF-H2O2 mixtures and hole injection into the silicon surface to be the rate-determining part of the reaction process.

The stoichiometry of metal assisted etching (MAE) of Si in V2O5+HF and HOOH+HF solutions

“…A solution of HOOH + HF does not etch Si at an appreciable rate, much less than 0.01 nm s À1 at the concentrations used in this study [46,47]. However, HOOH + HF is the most commonly used solution for MAE.…”

Regenerative Electroless Etching of Silicon

“…[9] For example, using the data of Gondek et al [10] and that of Ref. [9] For example, using the data of Gondek et al [10] and that of Ref.…”

Environmental Emissions from Chemical Etching Synthesis of Silicon Nanotube for Lithium Ion Battery Applications

“…According to Equations (2) and (3), as a typical Si-etching chemical, HF removes the SiO 2 from the surface of the Si wafer and continues to react with the Si beneath the SiO 2 surface layer. H 2 O 2 is added as a catalyst in the second step to accelerate the etching [22]. The reaction of HF and Si results in two gases, H 2 and SiF 4 , while SiF 4 is dissolved in HF to form H 2 SiF 6 (Equation (5)), leaving only H 2 gaseous emission from the etching system.…”