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

Autor:	Serge Charlebois, Serge Ecoffey, Francois Boone, Luc Frechette, Jacques Renaud, Naresh Miriyala, Mohamed Boucherit, Frederic Banville, Mohamed Najah, Mark Ferguson
Rok vydání:	2022
Předmět:	Renewable Energy Sustainability and the Environment Materials Chemistry Electrochemistry Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials
Zdroj:	Journal of The Electrochemical Society. 169:083504
ISSN:	1945-7111 0013-4651
DOI:	10.1149/1945-7111/ac8769
Popis:	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 μm) 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 μm-thick Au. We discuss the electrochemical origin of this mitigated galvanic undercut.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::21ad1100d4039be90930495cb90d5fa7 https://doi.org/10.1149/1945-7111/ac8769 Zobrazit plný text záznamu