Fabrication Process Research Of Spherical Microlens Array Based On Gray Scale Lithography And Nanoimprinting

With the integration and development of multidisciplinary technologies such as optics,mechanics,and electricity,traditional optical devices have been unable to meet the highprecision requirements of contemporary precision optical equipment for optical components due to their large number of components,large volume,and poor anti-interference ability.The emergence of micro-optical components has brought dawn to the solution of this problem and opened up a wider range of application scenarios.The spherical microlens array is an important micro-optical element,which is composed of a certain number of spherical lens units arranged in a certain way.Compared with traditional optical components,it can better meet the needs of miniaturization,arraying,lightweight and integration.However,the current manufacturing process of the microlens is cumbersome and costly,which limits its development to a certain extent.To this end,in order to explore a high-precision and repeatable processing technology for spherical microlens arrays,this paper has carried out research on the process of making spherical microlens arrays by gray-scale lithography and nanoimprint technology.The main research contents are as follows:Based on the principle of gray-scale mask lithography,the simulation and experimental research of making spherical micro-lens array by gray-scale lithography is carried out.Firstly,the black-and-white binary masks with different transmittances at different positions were drawn by the principle of gray-scale coding,and the experimental masks of gray-scale lithography were made.Then Silvaco TCAD software was used to simulate the light field distribution on the photoresist surface,and the distance between the proximity lithography mask and the photoresist surface was determined.To verify the feasibility of the process,the process experiment of making spherical microlens array by grayscale lithography was carried out,and the influence law and reason of soft baking temperature,soft baking time,exposure time and development time on the quality of lithography were analyzed and studied.Combined with the nanoimprint theory,the influence of various parameters on the filling rate of the imprint is studied through hot imprint simulation.Firstly,the mechanical state and mechanical behavior,creep,stress relaxation,time-temperature equivalence of the polymer are discussed,and the forming mechanism of the polymer is studied.Then the Maxwell model and the generalized Maxwell model,which characterize the viscoelasticity of polymers,are compared.The results show that the generalized Maxwell model can more accurately describe the mechanical properties of polymers.Finally,Abaqus was used to perform finite element simulation analysis on the nanoimprinting process,and the effects of imprinting temperature,imprinting pressure,mold structure duty cycle,mold structure size on the filling rate were studied separately,and the subsequent hot embossing and ultraviolet imprinting The selection of experimental parameters has certain guiding significance.The process of making spherical microlens arrays by nano imprinting was explored,including mold making,anti-adhesion treatment,imprinting experiments,and ICP dry etching.First,the metal nickel mold is cut by a single-point diamond cutting method,and then a variety of methods are used to perform anti-sticking treatment on the mold.Afterwards,hot embossing and ultraviolet embossing processes were used to make spherical microlens arrays,and the best combination of process parameters was obtained through orthogonal experiments,and the accuracy was verified by experiments,and the reasons for the molding defects were analyzed.Finally,ICP dry etching was used to transfer the pattern.In order to accurately etch the microstructure on the imprinting glue onto the silicon substrate,the gas composition,flow rate,and power were explored experiments with a selection ratio of 1:1,and used The corresponding etching parameters complete the etching process of the spherical microlens array.The root mean square error of the etching result is 54.166 nm,and the surface roughness is about 6.76 nm.