Graph of the SiO2 etch rates as function of the HBr flow. The etching conditions are a 30 sccm SF6 flow; a 60 sccm O2flow; 0–60 sccm HBr flow; rf bias power of 1000 W; rf source power of 150 W; and a pressure of 25 mTorr. A peak in the etch rates is reached for a 30 sccm HBr flow.
SEM micrographs of Si NWs etched with run 1 conditions.
SEM micrographs of Si NWs etched with run 2 conditions.
SEM micrographs of Si NWs etched with run 3 conditions. The diameter of the NWs is 200 nm and the length is 12 μm.
(Color online) SEM image of the Si NW array after HF dip.
(Color online) SEM image of the Si NW sidewall roughness after SF6/02/HBr/SiF4 etching. (a) Top of the NWs (after HF dip). (b) Bottom of the NWs (after HF dip).
(Color online) Si NW sidewall roughness after curing with 800 °C H2 annealing.
(Color online) (a) SEM micrographs of Si NWs obtained via Cl2/N2 etching. The diameter is 150 nm, and the length is 1.5 μm. (b) SEM high-magnification view of the NW sidewall showing the low roughness of these NWs.
SEM view of 250 nm-diameter and 2 μm-long SiGe NWs after Cl2/N2 etching. The “bowing effect” can be seen on the sidewalls.
SEM view of 90 nm-diameter and 1 μm-long SiGe NWs after Cl2/N2 etching. No bowing can be observed on the sidewalls.
Summary of experimental gas flow in the SF6/O2/HBr/SiF4 chemistry.
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