Research On Self-mask Growth Mechanism Of High-performance Antireflection Micro-nano Structures

The comprehensive performances of optical system can be effectively improved by broadband antireflection?AR?technology.Studies have found that multilayered AR films and antireflection micro-nano structures?ARSs?have broadband AR properties.The development of ARSs is in the ascendant due to their inherent advantages.The preparation of ARSs mainly includes mask prepared technology and etching technology.At present,the development of ARSs is mainly limited by the mask prepared technology.Based on this background,a new growth mechanism of ARSs was found by systematic and detailed research,which is called one-step self-masking reactive-ion-etching?RIE?broadband ARSs induced by metal nanodots on fused silica.Based on the rigorous vector diffraction theory,the finite-difference time-domain?FDTD?method was used to establish the theoretical analysis model of periodic ARSs.The effects of various parameters,such as duty cycle,height and period of ARSs were analyzed.The results show that the AR efficiency of ARSs is mostly determined by the duty cycle.The AR wavelength band is mostly determined by the height of ARSs.The effect of the period on the optical properties of ARSs is mainly manifested as the appearance of high order diffraction when the period reaches a certain degree.In experiments,a single variable method was used to systematically study the effects of various process parameters,such as gas flow ratio,chamber pressure,etching power,and etching time on the generation of ARSs and its optical properties.With an increase in CHF₃ and Ar gas flow ratios,the relative duty cycle of ARSs increases firstly and then decreases,the average height of ARSs gradually increases,and the AR performance increases firstly and then decreases.With an increase in etching power,the relative duty cycle of ARSs gradually increases,the average height of ARSs gradually increases,and the optical performance of ARSs gradually increases.ARSs cannot be generated when the pressure is higher than 10 Pa.The wider wavelength band AR properties are possessed by the ARSs as the etching pressure gradually decreases.With an increase in etching time,the ARS growth processes are obtained.In this mechanism,metal-fluoride nanodots?mainly ferrous-fluoride?were used to induce and gather stable fluorocarbon polymer etching inhibitors in the RIE polymers as masks.There are some advantages for this growth mechanism.The experimental period is short,the production principle is simple,the experimental operation is convenient,the preparation cost is low,and the prepared ARSs have a large area without defects.For the first time,in this paper,a sample with a transmittance in the visible wavelength range increased from approximately 93%for the polished fused silica to above 99%for the double-side ARSs on fused silica was prepared by a domestic equipment in this generation mechanism.After researches,it was found that the ARSs surface has an excellent superhydrophilicity.The ARSs prepared in this growth mechanism have large-area and non-defects.Therefore,the ARSs obtained in this paper can be applied in many areas.