Document Type

Conference Proceeding

Publication Date

2011

Abstract

From fundamental considerations of the surface chemistry of Si etching in fluoride solutions as well as pore formation and propagation, we develop a mechanistic understanding of what must be known for rational development of etchants: (1) an acidic fluoride solution because the presence of OH- promotes step flow etching, (2) sufficiently high fluoride concentration compared to the oxidant concentration, (3) the oxidant must be able to inject holes into the Si valance band at a sufficient rate, hence E degrees > similar to 0.7 V is required, (4) oxide formation needs to be slow or nonexistent so as to avoid the formation of a uniform oxide and associated electropolishing, (5) reduction of the oxidant must lead to soluble products, (6) film homogeneity is enhanced if the oxidant's half-reaction does not evolve gas, and finally (7) the net etching reaction has to be sufficiently anisotropic to support pore nucleation and propagation.

Comments

© The Electrochemical Society, Inc. 2011. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published at http://ecst.ecsdl.org/content/33/16/23.abstract.

Publication Title

Pits and Pores 4: New Materials and Applications - in Memory of Ulrich Gosele

DOI

10.1149/1.3553152

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