Chemistry Reference
In-Depth Information
4.7. ETCHING MECHANISMS
4.7.1. Reactions
In Nonfluoride Solutions.
In water or nonfluoride aqueous solutions the disso-
lution of silicon oxides is determined by the reaction with water:
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The elemental reactions leading to the breaking of the Si-O bond involve at least three
steps—adsorption, activated complex formation, and hydrolysis—as shown in Fig.
4.29.
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The formation of the bond between the adsorbed hydrogen and the bridging
oxygen weakens the Si-O bond. Among the species in water, ions perturb the bond
the most; the relative effect of different ions and molecules on the bond strength of the
bridging oxygen follows the sequence:
