Research Of Airshowering For The Unit Of The Immersion Lithography

Through filling ultrapure water between the projection lens and silicon wafer,immersion lithography can form a stable immersion flow field and improve the resolution of lithography.The immersion unit is the core component of immersion lithography,and the temperature accuracy and stability of the micro-environment,will affect the immersion liquid's refractive index?viscosity and imaging quality of the immersion lithography.Therefore,the immersion lithography machine needs to develop a specific device,which can control the temperature of the micro-environment precisely.In this thesis,the uniform gas bath with stable temperature was studied,and the main contents are briefly expressed as the followings:Firstly,the functional and performance requirements of the gas's temperature for the micro-environment bath were analyzed.Through comparing of dircect and indirect temperature control,the last one,containing gas-liqiud exchange,was selected.And the selection of the key components was done.Related electrical system was then designed and the PLC control programming was also carried out.Based on the demand of the compactness,the mechanical structure design of this system was investigated.Further more,the framework of temperature control was proposed,and relative functions such as the communication,interface and the database were realized.Secondly,design and optimization of micro-environment thermostatic gas bath box.An air supply system with porous plate was investigated.Following the air supply scheme,different air bath box structures were developed,and their characteristics of temperature field and velocity field were carefully compared through CFX numerical simulation.Furthermore,the heat loss of gas in the loop was also investigated.Finally,control strategy of micro-environment investigation.Mathematical models,related to different components of the micro-environment temperature control system,were established.Considering the characteristics of the system's non-linearity,multiple time delays and multiple perturbations,a cascade control structure was finally adopted.The parameter tuning of the master and vice PID controllers was then carried out.At last,the suppression of external disturbance by the gas temperature control system under cascade control structure was testing and validated.