光电化学腐蚀法制备高长径比硅微通道

在高长径比硅微通道光电化学腐蚀中,需要根据通道尺寸要求实时修正腐蚀电流.研究了物质输运、暗电流对腐蚀电流控制的影响,并提出了腐蚀电流的控制曲线.根据电解液扩散方程和边界条件,推导出通道尖端处HF质量分数与通道长度的关系.根据腐蚀后的暗扫描I-V曲线计算出暗电流密度.与腐蚀电流密度相比,阴离子表面活性剂的暗电流可忽略不计,进而获得了腐蚀电流修正曲线.根据腐蚀电流修正曲线,通过控制光照强度制备出高长径比(大于60)的等径硅微通道阵列.对修正的腐蚀电流进行调整,制备出通道尺寸空间周期性变化的硅微通道结构.研究结果可为高长径比硅微通道的制备提供技术方法.

Fabrication of High Aspect Ratio Silicon Microchannel by Photo-Electrochemical Etching

In photo-electrochemical etching of high aspect ratio silicon microchannel,the etching current should be corrected based on requested channel diameter of silicon microchannel structure.The influence of the mass transport and dark current on the control of etching current were researched,and the control curve of etching current was presented.According to the diffusion equation and the boundary conditions of electrolyte,the relation of the HF mass fraction at channel tip and the channel length was deduced.The dark current density was calculated based on the dark Ⅰ-Ⅴ scanning curve after silicon microchannel by photo-electrochemical etching.Compared with the etching current density,the dark current density of anionic surfactants can be negligible in photo-electrochemical etching,and the curve of correction etching current was obtained based on this relation.The high aspect ratio (more than 60) silicon microchannel arrays with constant channel diameter were fabricated by adjusting the illumination based on correction etching current curve.And the high aspect ratio silicon microchannel with periodic variations of channel diameter was fabricated by the adjusted correction etching current.This resesrch will provide a fabrication method for the high aspect ratio silicon microchannel.