Use of $SiO2$ nanoparticles as etch mask to generate Si nanorods by reactive ion etch

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 $SF6∕O2$ and $SF6∕CHF3$ is tuned to achieve high anisotropy. The gas specie of $SF6∕O2$ can reach 90% anisotropy, 84° taper angle, and 10:1 selectivity when $SiO2$ is used as the etching mask. The gas species of $SF6∕CHF3$ 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 $2×1011cm−2$⁠. 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 $100nm$⁠.