Plasma etched initial pits for electrochemically etched macroporous silicon structures

Abstract

Macroporous silicon structures of different shapes were prepared by electrochemical etching of n-type silicon in diluted HF under illumination. Depths reaching 80 µm and 40:1 aspect ratios were achieved. A PECVD amorphous silicon layer was used as a masking layer. Undoped amorphous silicon was found to be quite resistant to the HF etching solution. The initial pits were prepared by reactive ion etching (RIE) instead of the conventional anisotropic alkaline wet etching. The advantages of RIE-made initial pits were demonstrated by electrochemically etched Fresnel lenses. Electrochemically etched complex trenches with curved shapes have been demonstrated for the first time. Illumination modulation was employed to fabricate arrays of macropores with variable diameters and free-standing macroporous film.

Silicon Porosification: State of the Art

“…Additionally, when carefully selecting the etching conditions and masking layer, RIE can offer much smaller and deeper initial pits compared to alkaline etching. 352 …”

Atomic Layer Deposition of Al2O3, TiO2 and ZnO Films into High Aspect Ratio Pores

“…Silicon macropore formation was initiated by either TMAH or RIE initial pits. Electrochemical etching was carried out as described in [7]. Aspect ratios of 50:1 were routinely obtained (Fig.…”

Luminescent Properties of Porous Silicon

“…RIE offers the opportunity to fabricate complex pattern shapes, for instance curved or round structures, whereas KOH pits are limited to rectangles. Additionally, when carefully selecting the etching conditions and masking layer, RIE can offer much smaller and deeper initial pits compared to alkaline etching (Grigoras et al 2001 …”