Design And Validation On The Model Of Front-end Immersion Temperature Control System In Immersion Lithography

Immersion lithography is the most well-rounded method in the market of high-end lithography machine at present.By the refraction of optical lens and liquid,the features on the mask are projected to the silicon wafer.Through step scanning and physicochemical reaction,the final IC can be batch manufactured,of which the temperature stability of liquid is one of the key factors affecting the final feature size.The main purpose of this article is to design a high-precision temperature system used in immersion lithography.There following the details:The input temperature index is designed according to the temperature gradient of mainstream field.By analysis of the index,the three-level temperature control scheme is set up,of which the second-level control system is what discussed in the article.By means of thesis of heat and energy conservation,the mathematical modeling of the second-level control system is established.Besides,identification technique is introduced to estimate the non-linear parts that can't be set up accurately.The modeling of these parts can be estimated by ARX algorithm through input and output of experiment after filtering and sampling.And the complete transfer function can be got.To achieve the target performance,there some rectification methods are introduced.By cascade compensation,a PID controller based on ITAE rules is designed in the system.In order to get the optimal control effect,several optimization algorithms are applied to the parameter tuning of controller.Besides,feedforward and feedback compensation are used to reduce the temperature impacts caused by several interferences,through which a cascade controller is adopted.Finally,an experiment is designed to verify the control effect of system adjusted.It shows that the temperature precision can be controlled between 0.07?,which meet the requirement of 0.1?/30 s.