Silicon nanorods 20nm in diameter are fabricated by reactive ion etch (RIE) to study anisotropy and damage profile in decananometer scale. RIE of gas mixture of SF6O2 and SF6CHF3 is tuned to achieve high anisotropy. The gas specie of SF6O2 can reach 90% anisotropy, 84° taper angle, and 10:1 selectivity when SiO2 is used as the etching mask. The gas species of SF6CHF3 can reach 95% anisotropy, 87° taper angle, and 10:1 selectivity with Cr as the mask. The fabrication technique of nanorods uses a monolayer of silicon dioxide nanoparticle as the etching mask. The nanorods uniformly cover up the entire 2in. wafers with high density of 2×1011cm2. Surface damageafter the etching process of nanostructures is monitored using the microwave-reflectance photoconductance decay with KOH removal-and-probe technique. Highly damaged silicon is found within a depth of 30nm and the lightly damaged part extends more than 100nm.

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