Use of SiO_2 nanoparticles as etch mask to generate Si nanorods by reactive ion etch

摘要

Silicon nanorods 20 nm in diameter are fabricated by reactive ion etch (RIE) to study anisotropy and damage profile in decananometer scale. RIE of gas mixture of SF_6/O_2 and SF_6/CHF_3 is tuned to achieve high anisotropy. The gas specie of SF_6/O_2 can reach 90% anisotropy, 84° taper angle, and 10:1 selectivity when SiO_2 is used as the etching mask. The gas species of SF_6/CHF_3 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 2 in. wafers with high density of 2X 10~(11) cm~(-2). Surface damage after 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 30 nm and the lightly damaged part extends more than 100 nm.