Effect Of Etching Temperature On Friction-induced Nanofabrication On Monocrystalline Silicon

Owing to its excellent mechanical,electronic and physical properties,monocrystalline silicon has been widely used in the construction of semiconductor devices,large scale integrated circuit,solar photovoltaic battery and so on.Therefore,the Si-based nanofabrication approaches play an important role in the field of nanotechnology,which are the basis for the realization of nanoscale products.At present,the traditional Si-based nanofabrication approaches include etching process,photolithography,nanoimprint lithography,focused ion beam technology,scanning probe microscope machining and so on.They are further expanding the scope of application of nanofabrication in the improvement of existing technology.Recently,friction-induced selective etching nanofabrication has become a new type of nano fabrication method,which is based on the combination of scanning probe microscope scanning and post-etching.With the advantages of simple processing,high flexibility and low cost,friction-induced selective etching nanofabrication can be realized independent of the template and the applied voltage field.However,the friction-induced selective etching process is based on chemical reaction,where the influence of temperature on the selective etching process is not clear.To clarify the processing mechanism for the friction-induced selective etching,it is urgent to carry out the related research.By using the homemade multi-probe instrument,atomic force microscopy,in-situ nanomechanical test system and related analysis methods,the effect of etching temperature on friction-induced selective etching on silicon were studied,and the influence mechanism was investigated.Based on this study,an approach on silicon surface through indentation-induced selective etching was established.The main content and innovation point of this paper are summarized as below.(1)The effect of etching temperature on the selective etching of silicon wafer surface was investigated.After the etching in KOH solution,the height of the hillock on silicon increases with temperature for the same etching time.When the etching temperature is 80℃,the protrusive structure formed on silicon surface will appear highly uneven.With the increase of etching temperature,silicon surface becomes rougher,and the rougher surface leads to higher hydrophilicity,but reduces micro mechanical properties to some extent.XPS observation suggests that no obvious contamination can be detected on the silicon surface after etching at different temperatures.(2)The mechanism of etching temperature on friction-induced selective etching was investigated.Fromthe analysis of the Arrhenius equation,more frequent collisions rose by the increase of etching temperature will result in severe chemical reaction,which leads to the height of protrusive structure increasing.According to the fitting curve of experimental data,the natural logarithm of selective etching rate is changing linearly with the reciprocal temperature.And the activation energy Ea for the selective etching can be estimated as 0.33-0.38 eV.(3)The indentation-induced selective etching nanofabrication method on monocrystalline silicon was proposed.Based the mechanism of friction-induced by selective etching on monocrystalline silicon,the indentation-induced selective etching nanofabrication method is established.The etching time and indentation load are determining the height and radius of curvature of pyramid tips.With the increase of etching time or load,the tip height is also increasing.By the control of machining parameters at the same time,multiple tips can be processed easily after etching.In this paper,the effect of temperature on friction-induced selective etching of silicon was studied systematically and the fabrication conditions were optimized,which is expect to pave a road of controllable processing for high aspect ratio structure on silicon surface.The fundamentals for friction-induced selective etching were further enriched.At the same time,the indentation-induced selective etching nanofabrication method was proposed.The highly uniform protrusive structure can be fabricated by indentation-induced selective etching,which can be employed for carry out multiple-tip array processing.