Integration of silicon nanowire bridges in microtrenches with perpendicular bottom-up growth promoted by surface nanoholes

Abstract

Abstract An integration method of silicon nanowires (SiNWs) bridges in microtrenches was demonstrated combining a local arrangement of catalyst Au nanoparticles by two-step UV lithography, and a vapor–liquid–solid (VLS) bottom-up growth with perpendicularity promotion by surface nanoholes with metal-assisted chemical etching. Au nanoparticles with a diameter of 60 nm were arranged on one-side walls of 10 µm wide microtrenches, with two types of area sizes to evaluate the influence on the yield of SiNWs bridges reaching opposite sidewalls. A four-hour VLS process at 500 °C produced perpendicular SiNWs bridges in the microtrenches, and a higher yield was obtained with a narrow-area arrangement: a 30.7% ratio of densities of SiNWs bridges to Au nanoparticles, and a 2.1/µm2 density in the arrangement area. Fewer SiNWs showed initial oblique growth there, and most of the bridges had a linear morphology. The yield of SiNWs bridges was discussed focusing on depth positions in microtrenches and the depths of surface nanoholes.