Research On Photoelectrochemical Etching Technology Of N-type Silicon Microchannel Array

With the development of Photoelectrochemical etching technology of macroporous N-type silicon microchannel,it has better applications in the fields of optical fiber panel,Cs I(Tl)X-ray scintillation screen and waveguide X-ray scintillation screen.N-type silicon microchannel can be prepared by Photoelectrochemical etching experiment,and the microchannel structure is obviously different due to different conditions such as electrolyte composition,silicon electrode doping concentration,induced pit arrangement,reaction temperature and the like.Therefore,this paper has carried on the following research:The influence of induced pits on the fabrication of macroporous N-type silicon microchannel array was studied.The induced pit structure model was established.The current density and potential at the induced pits and the influence of the induced pit structure on the microchannel during the Photoelectrochemical etching process were obtained by theoretical simulation.The simulation results show that the induced pits play an active role in the Photoelectrochemical etching of silicon microchannels.When the silicon microchannel array is prepared by Photoelectrochemical etching,the silicon wafer with induced pits will preferentially react at the induced pits.Finally,the prepared N-type silicon microchannel array is completely consistent with the structure arrangement of the induced pits.N-type silicon microchannels with different surface morphologies were fabricated by using electrolyte containing nonionic Triton X-100,cationic HTAC,anionic las and HF without surfactant,respectively.The effect of surfactants on the polarization process was studied by electrochemical analysis.The morphology of silicon microchannel was observed by scanning electron microscopy,and the effect of surfactant type in electrolyte on N-type silicon microchannel was comprehensively analyzed by mass loss measurement and contact angle measurement.The results show that the surfactant has a certain effect on the space charge layer and Helmholtz layer of N-type silicon,and the growth rate of silicon microchannel increases after adding the surfactant.From the growth rate and surface morphology,the nonionic surfactant is the best in the Photoelectrochemical etching of N-type silicon microchannel.In this paper,the effect of temperature on the morphology of macroporous N-type silicon microchannel array in the process of Photoelectrochemical etching was studied.It was found that when the etching temperature was too low,the growth of silicon microchannel stopped,and when the etching temperature was too high,the surface aperture of silicon microchannel became larger.Therefore,the relationship between temperature and hole mobility and diffusion coefficient is discussed.The charge transfer resistance of the equivalent circuit at different temperature was measured by AC impedance method.The results show that the higher the temperature,the smaller the charge transfer resistance.The effect of doping concentration of silicon electrode on the fabrication of macroporous N-type silicon microchannel array was studied.The silicon materials with resistivity of 10-20 ?·cm and > 10000 ?·cm were selected for comparison.The microchannel morphology was observed by scanning electron microscopy,and the effect of silicon electrode doping concentration on N-type silicon microchannel was comprehensively analyzed.The results show that N-type silicon with resistivity larger than10000 ?·cm is more suitable for fabricating macroporous N-type silicon microchannel array.