Title :
A practical galvanic etch-stop in KOH using sodium hypochlorite
Author :
Connolly, E.J. ; Sakarya, S. ; French, P.J. ; Xia, X.H. ; Kelly, J.J.
Author_Institution :
Delft Univ. of Technol., Netherlands
Abstract :
We report a new galvanic etch-stop (ES) for KOH which requires a gold:exposed Si area ratio of only ∼1. Previously, the galvanic ES was shown to be effective only in TMAH with a gold:exposed Si area ∼16. This limitation was due to insufficient oxygen at the gold electrode. Studies using hypochlorite (OCl) have shown it to be a strong oxidising agent in KOH, thus suitable for shifting electrochemical potentials, and for micropyramid suppression during etching. This new ES works by adding small amounts of sodium hypochlorite, NaOCl, to KOH solutions. The dependency of the galvanic ES on KOH concentration and temperature is investigated. Also, we report on the effects of the added NaOCl on etch rates. SEM images are used to examine the galvanically etch-stopped membranes.
Keywords :
chemical potential; electrochemistry; elemental semiconductors; etching; gold; potassium compounds; silicon; sodium compounds; KOH; NaOCl; Si; micropyramid suppression; practical galvanic etch-stop; shifting electrochemical potentials; sodium hypochlorite; Biomembranes; Current density; Electrodes; Etching; Galvanizing; Gold; Photovoltaic systems; Silicon; Solar power generation; Thickness control;
Conference_Titel :
Micro Electro Mechanical Systems, 2003. MEMS-03 Kyoto. IEEE The Sixteenth Annual International Conference on
Print_ISBN :
0-7803-7744-3
DOI :
10.1109/MEMSYS.2003.1189812
