Research On Controllable Liquid Catalytic Micronano Etching Process

At the closing ceremony of the 20 th China Association for Science and Technology Annual Conference,the China Association for Science and Technology released 60 major scientific issues and major engineering and technical problems in 12 fields.Among them,nano-fibers in the field of advanced materials attracted much attention.As a one-dimensional nano-material,single crystal silicon nano-wires with its superior mechanical properties,electro-optical properties,biochemical sensing properties,and thermoelectric properties are potentially useful in optical devices,electronic devices,and biosensors.Therefore,the preparation of nanowire arrays with specified morphology characteristics at low cost and high efficiency becomes an important research hotspot.This paper is supported by National Natural Science Foundation of China(The research of controlled droplet catalytic deposition and etch nano-fabrication,No.51675141).The main focus is on the preparation of nanowire arrays by controlled droplet catalytic lithography and the processing of miniature petri dishes and micro-fluidic channels with nano-villi.Firstly,the etch mechanism of one-step and two-step methods for nanowire arrays prepared by silver catalytic etch method has been explored,and the two-valence and four-valence dissolution models of silicon are theoretically analyzed.At the same time,air-controlled micro-tube droplet operation method is selected in the manipulation of etching solutions.Based on the Young-Laplace equation,a moving liquid bridge is established considering the contact angle hysteresis between the microtubule end,the etching droplet and the silicon substrate,and the size and direction of the bridge fluid force between the microtubule end and the silicon substrate are theoretically calculated and analyzed.Secondly,based on the theoretical study of the air-controlled micro-tube droplet operation method,combined with the characteristics and requirements of the silver-catalyzed etching process,a controllable droplet catalytic etch processing system are constructed which includes an air-controlled droplet manipulation unit,a microscopic visual imaging unit,a motion positioning unit,and a parallel corner unit.In addition,an analysis of the processing strategies and control methods based on microscopic visual feedback has been performed and computer software for the coexistence of a real-time programming interface,a detection control domain,and a dual display interface is prepared.We also add the "no load detection" instruction to detect the distance changes between micro-tube end and the silicon substrate.Thirdly,using silver nanoparticles as catalyst in single-crystal silicon etching,silicon nanowire arrays with different aspect ratios are prepared and the surface morphology of the silicon wafer can be changed.The effect of parameters on the aspect ratio and micro/nanostructure of silicon nano-wires is summarized and analyzed by experimentally changing the parameters such as silver nitrate concentration,hydrogen peroxide concentration,etching time,etching temperature,and illumination in the etching conditions,thereby the morphology control is realized.Finally,the reflectivity of the etched silicon surface is tested.Experiments show that the surface micro-nano structure of the etched silicon wafer has a significant anti-reflection effect on light with a wavelength of 400-2000 nm.Finally,using the micro-etching processing system that has been set up,an experimental study of controlled droplet catalytic etch is conducted.First we analyze the experimental mechanism of controllable droplet catalytic etching and process the etching through direct write catalytic etching and underwater catalytic etching,then the influence on the morphological characteristics of the point and linear type etching is summarized by changing the applied pressure,microtubule residence time,and microtubule motion speed.Finally,miniature petri dishes and micro-fluidic channels with nano-villi are prepared based on the point and linear etching characteristics,and the application of different etching patterns in medicine and biology is analyzed.