Fabrication Of High Aspect Ratio Micro-nanostructures And Their Application In Surface Enhanced Raman Spectroscop

The rapid development of semiconductor technology has put forward new requirements for the manufacturing technology of micro and nanostructures-the manufacturing of high aspect ratio micro and nanostructures.At present,the relevant manufacturing processes of this structure have been widely studied and applied in many fields,but there are still problems such as complex processes,high debugging difficulties,and high processing costs in the manufacturing process.In response to the above issues,this paper is based on ICP etching technology and analyzed through a large number of experiments to obtain efficient etching process parameters.By using low-cost photoresist as a mask,controllable manufacturing of high aspect ratio micro/nanostructures is achieved through photolithography.Furthermore,simulation,experiments,and parametric analysis methods are combined to systematically study the surface enhanced Raman performance of high aspect ratio micro/nanostructures.The main research work is as follows:（1）Research on a simple and efficient processing technology for high aspect ratio structures using photoresist as a maskFirstly,by comparing the advantages and disadvantages of various processing methods,ICP etching is selected as the processing method for high aspect ratio micro/nanostructure etching experiments.The main parameters in the etching process:reaction time,reaction chamber pressure,etching/passivation gas flow ratio and ICP source power were tested,and five groups of continuous variables were set by the Control variates.Analyze the etching experimental results,obtain the relationship curve between etching rate and various parameters,as well as the influence of various parameters on the uniformity of structural morphology,and obtain efficient and controllable processing parameters for high aspect ratio micro nano structures.The etching processing parameters determined by using photoresist as the etching mask are:reaction time 0.625s,reaction chamber pressure 30m Torr,etching/passivation gas flow rate 160sccm/10sccm,ICP source power 2000W,achieving an etching rate of 5.07μm/min.Under this process,stable processing of micro/nanostructures with a aspect ratio of approximately 129 and a sidewall inclination angle of approximately 90.4°can be achieved on the silicon surface without the need for additional metal masks.（2）Study the application of high aspect ratio micro nano structures in surface enhanced Raman spectroscopyFirstly,the time-domain differential software FDTD was used to simulate the electric field of three types of substrates,and the electric field distribution of gold particle unstructured silicon substrate and gold particle high aspect ratio micro/nano structured silicon substrate were obtained.By comparing the simulation results,it was found that gold particle high aspect ratio micro/nano structured silicon substrate can generate a large number of stable"hot spots"between gold particles and silicon under different polarization directions of excitation light sources.Furthermore,silicon based micro/nano structures with different aspect ratios were fabricated by the etching process studied.The formation and modification of gold particles were completed by the reduction reaction of chloroauric acid under ultraviolet light.rhodamine 6G（R6G）was used as the probe molecule,and aqueous solutions with different concentrations were configured for Raman detection experiments.The results show that the detection limit of the prepared gold particle unstructured silicon substrate at R6G is 10^-6M,and then the experiments of gold particle high aspect ratio micro nano structured silicon substrate with different aspect ratios are carried out.It is found that the detection signal of the substrate is enhanced with the increase of aspect ratio.When the aspect ratio is 10,the signal intensity is nearly three times stronger than that of the unstructured substrate,This indicates that high aspect ratio structures can effectively leverage the advantages of high specific surface area in Raman detection,which helps to further enhance the signal.