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Article Dans Une Revue Journal of The Electrochemical Society Année : 2022

Mitigating Re-Entrant Etch Profile Undercut in Au Etch with an Aqua Regia Variant

Résumé

We investigate the re-entrant undercut profile resulting from Au wet etching for patterning micron range thick films using an aqua regia-based solution in comparison with an iodine-iodide-based commercial etchant. Our work discriminates between two undercutting mechanisms: galvanic acceleration of etch rate at the Au adhesion or barrier layer, and delamination-based undercutting. We tracked etch outcomes of feature size reduction from photoresist size, undercut Au in cross-section and lift-off of small (5–10 μ m) features. Results indicate that galvanic undercutting is well-mitigated by the aqua regia solution compared to commercial etchant results. Good Au adhesion eliminates undercut for 500 nm-thick Au and mitigates it by ∼80% for 1 μ m-thick Au. We discuss the electrochemical origin of this mitigated galvanic undercut.

Dates et versions

hal-03821782 , version 1 (19-10-2022)

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Citer

Mark Ferguson, Mohamed Najah, Frédéric Banville, Mohamed Boucherit, Naresh Miriyala, et al.. Mitigating Re-Entrant Etch Profile Undercut in Au Etch with an Aqua Regia Variant. Journal of The Electrochemical Society, 2022, 169 (8), pp.083504. ⟨10.1149/1945-7111/ac8769⟩. ⟨hal-03821782⟩
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