Study On Low Temperature Plasma Etching Technique Of Lobster-eye Lens

The special biomimetic reflective structure of lobster-eye lens makes it different from the traditional optical lens.Based on the principle of grazing incidence reflection imaging,the electromagnetic radiation fluxes converge to the same image point after passing through the square aperture microchannel similar to "Angle reflector",which can make the image brighter and contain more abundant information.The lobster eye lens has broad application prospects in both X-ray and infrared bands due to its strong light-gathering ability,large field of view,high resolution,and broad spectrum imaging characteristics.Because the wavelength of the X-ray spectrum is extremely short,it is highly sensitive to the roughness of the reflective surface,so the manufacturing process technology of the microchannel is particularly important.This paper focuses on improving the imaging performance of the lobster eye lens,and conducts experimental research on the low-temperature inductively coupled plasma(ICP)dry etching technology.Based on this,the focusing characteristics of the lobster eye lens in the Xray spectrum are simulated analysis.The main content of this dissertation includes:1)The ray tracing mathematical model of lobster-eye lens is established by prism expansion method.According to the mathematical model and from the perspective of optical design,the focusing characteristics of the lobster-eye lens with two different structures,meridional and square-channel,were compared through Matlab simulation analysis,and the structural parameters of the lobster eye lens microchannel hole are determined.2)Based on Fresnel reflection principle,the effects of different coating materials,coating thickness and coating surface roughness on X-ray focusing characteristics of different energies were analyzed and compared by Matlab simulation for meridian lobster-eye lens with better focusing characteristics,the parameters of the reflective coating on the inner wall of the lobster eye lens microchannel hole are determined.3)The advantages and disadvantages of Bosch process,mixed gas process and low temperature process were compared,and the low temperature inductively coupled plasma(ICP)dry etching technology that can accurately control the etching morphology and etching rate was finally determined.Through parameter exploration,the improved parameters of the low-temperature continuous etching process were obtained,and a smooth,steep,high-aspect-ratio microchannel structure with a reflective surface was prepared.Based on the technical index requirements of the lobster eye lens,a low-temperature cyclic etching process was developed to prepare a higher aspect ratio and a well-shaped micro-channel hole structure.4)The etching results of different mask materials and process parameters are compared.In-depth analysis of the reasons for the deviation of the etched morphology from the expected due to the use of photoresist and silicon dioxide as the etching mask,and finally determined to choose a higher ratio and more resistant metal chromium as the etching mask;in-depth analysis The reason for the change of the etching result after the single process parameter is changed by the controlled variable method is obtained,and the law of the matching of the ionization degree and the physical and chemical process of each process parameter is obtained.