Study On The Thin Films Fabricated By Atomic Layer Deposition Of Large Curved Optical Elements

The applications of large curve optical element in optical system are more and more extensive,but the corresponding thin film deposition technologies are still defective.Atomic layer deposition?ALD?is emerged as an important thin film deposition technique for a variety of applications.ALD is able to meet the needs for atomic layer control and conformal deposition using sequential,self-limiting surface reactions.The self-limiting reaction of ALD leads to excellent step coverage and conformal deposition on high aspect ratio structures and large curve structures.The ALD process is dominated by surface reactions.There are temperature,reactant concentration,reaction activation,which are the factors of the surface reactions.In experiments,reactant concentration is the most significant factor of surface reactions.Based on this,this paper is carried out the concrete simulations and the experiments.The specific methods and conclusions are as following:In the simulation section,using SolidWorks builds the reaction chamber.Meshing the model by Gambit and using CFD simulates reactant concentration.According to the simulation results,we conclude that there is an optimized deposition area in the front part of ALD chamber,and the height of which is 1³ cm above the chamber floor.In the experimental section,the experimental verification of optimizing regional is carried out.The results of experiments on hemispherical substrate placed in different areas show that the maximum inconformity of the Al₂O₃ and TiO₂ films in the optimized area is 1.81%and 1.74%,respectively.Compared with other areas,the maximum inconformity of Al₂O₃ and TiO₂ films decreases by 47.1%and 50.8%.Based on the experimental results of single layer film,we deposite the antireflection film at 550nm,and band antireflection film at 550⁷50nm.Then,we analyse the errors occurring in the films.