Study On Coherent Porous Silicon Preparation By Photo-assisted Electrochemical Etching

Coherent porous silicon is regular arrangement of space,pore size uniform and orderly array.High aspect ratio coherent porous silicon with good back morphology is widely application in silicon microchannel plate,loop heat pipe and microneedles.In this paper,based on the n-type silicon,an experimental device was designed and built.And the coherent porous silicon samples were prepared.The photo-electrochemical experiments were carried out with different process parameters in the research process.After the process of polishing,the morphology of the back of the coherent porous silicon was observed by metallographic microscope.The effects of process parameters such as etching voltage,electrolyte temperature,HF concentration and light intensity on the morphology of coherent porous silicon were investigated.The relationship between pore size and etching current density was studied.Under the condition of electrolyte diffusion limit and the dark current of aperture control effects,according to the experimental data,the control curve of etching current was obtained.Prefer conditions for the preparation of coherent porous silicon were obtained.The etching voltage was 0.6V,the electrolyte temperature was 23?,the concentration of HF was 5 wt%,the light intensity was 85 mW/cm2.The morphology of the coherent porous silicon array affected by light intensity.And the light intensity controlled by etching current curve.