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Controlled Microfabrication of High‐Aspect‐Ratio Structures in Silicon at the Highest Etching Rates: The Role of H 2 O 2 in the Anodic Dissolution of Silicon in Acidic Electrolytes
Author(s) -
Cozzi Chiara,
Polito Giovanni,
Kolasinski Kurt W.,
Barillaro Giuseppe
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201604310
Subject(s) - materials science , dissolution , silicon , etching (microfabrication) , hydrofluoric acid , isotropic etching , reactive ion etching , nanotechnology , microfabrication , dry etching , electrochemistry , analytical chemistry (journal) , chemical engineering , optoelectronics , metallurgy , fabrication , electrode , chemistry , medicine , alternative medicine , layer (electronics) , pathology , chromatography , engineering
In this work the authors report on the controlled electrochemical etching of high‐aspect‐ratio (from 5 to 100) structures in silicon at the highest etching rates (from 3 to 10 µm min −1 ) at room temperature. This allows silicon microfabrication entering a previously unattainable region where etching of high‐aspect‐ratio structures (beyond 10) at high etching rate (over 3 µm min −1 ) was prohibited for both commercial and research technologies. Addition of an oxidant, namely H 2 O 2 , to a standard aqueous hydrofluoric (HF) acid electrolyte is used to dramatically change the stoichiometry of the silicon dissolution process under anodic biasing without loss of etching control accuracy at the higher depths (up to 200 µm). The authors show that the presence of H 2 O 2 reduces the valence of the dissolution process to 1, thus rendering the electrochemical etching more effective, and catalyzes the etching rate by opening a more efficient path for silicon dissolution with respect to the well‐known Gerischer mechanism, thus increasing the etching speed at both shorter and higher depths.