Study On Rapid Electrochemical Etching And Mechanism Of P-type Macroporous Silicon

Macroporous silicon is one of the research hotspots in the field of sensors and composite materials.It has the advantages of low cost,high aspect ratio,good mechanical properties,good adsorption and compatibility with integrated circuits.It is of great significance and value for biomedical,disease screening and composite material development.At present,the main bottleneck restricting the large-scale development and application of macroporous silicon is the low preparation efficiency,especially the low preparation rate of high aspect ratio macropores structures.Considering the effects of current density,etching time,HF concentration and resistivity on the preparation rate,aspect ratio,structure morphology and porosity of p-type macroporous silicon,the mechanism of rapid pore formation of p-type macropores and the mechanism of doping concentration on macropores morphology were explored.The main research contents and innovations are as follows:Firstly,the effects of parameters such as etching time,resistivity,HF concentration,and electrolyte composition on the microstructure of porous silicon were studied.The experimental results show that increasing the corrosion time and decreasing the HF concentration can increase the porosity.Reducing the concentration of HF can create regular macropore structures on low-resistance silicon;increasing the resistivity can effectively widen the parameter range for preparing regular macropores.The experiment also shows that the etching solution containing DMF is more suitable for the preparation of macroporous silicon than that containing DMSO.Secondly,the effect of parameters such as current density,corrosion time,HF concentration and resistivity on etching rate and aspect ratio was systematically explored.The results show that increasing the current density can result in increasing corrosion rate and aspect ratio;prolonging the etching time causes the etching rate to decrease continuously and the aspect ratio to increase continuously.Increasing the HF concentration and resistivity can increase the etching rate of macroporous silicon.When the aspect ratio reaches 110,the etching rate is still close to 16.4 ?m/min.In addition,the influence of corrosion parameters on the macropore morphology was also investigated.It was found that when the corrosion time was increased,the quality of the macropores became better first and then sharply deteriorated;reducing the current density could effectively extend the corrosion time.HF concentration and resistivity can also affect the macropore morphology.The larger the resistivity,the easier it is to obtain high-quality macropores.Under the same experimental parameters,adding pre etching structure to prepare macropore array can obtain the macropore with better quality.In this paper,the etching rate,aspect ratio,structure morphology and porosity of p-type macroporous silicon are systematically studied,and the mechanism of rapid pore formation of macroporous silicon and the effect of doping concentration on macropore morphology are explored.The preparation of macroporous array also has been explored.This study has accumulated experimental data and theoretical basis for the efficient preparation of p-type macroporoes structures and morphologies studies.