Development Of High Precision Refrigeration Circulating Chiller Based On Semiconductor

The processes of modern ultra-precision manufacture and measurement demand strict requirements of the working environment. Especially, lithography, the equipment for very large scale integrated circuits(VLSI) manufacturing, dramatically needs stable environment. However, conventional cooling methods can not meet the requirements because of its high level of integration. While the lithographic quality of the projection lens, the positioning accuracy of the moving parts and the accuracy of the measuring devices are extremely sensitive to the changes of environment in particularly to temperature changes. Therefore, it is a key technology that controlling environmental parameters, especially the temperature.High-precision circulating chiller temperature control system is an important component unit of step and scan lithography, micro and nano coordinate measuring machine, scanning probe microscopes and other ultra-precision equipment. In the context of application requirement, this paper develops a high-precision refrigeration circulating chiller based on semiconductor. The aim is to solve the problems of current circulating chiller, such as low-precision temperature control, long time adjustment, poor robustness and so on.So, the contents of this article as follows:Firstly, survey and analyze domestic and foreign high-precision circulating water temperature control system. Then, point out deficiencies of the principle, method or current products. And then according to the project requirements and design indicators, complete the scheme of circulating chiller temperature control system. The scheme selects semiconductor-cooling and electrical-heating methods, and high-power drives, high-precision control algorithm based on the characteristics of temperature control system and accuracy demands.Secondly, design and calculate the heat exchanger in detail, according to the solutions of high-precision temperature control system. Meanwhile, the amount of deformation, the flow field(velocity) and temperature distribution of the heat exchanger are simulated and analyzed in the ANSYS simulation platform. Also demonstrate the rationality and correctness of the design process, which provide direction for further optimization. Then, complete parameter selection of the structure.Then, design high-precision temperature control algorithm in detail, aiming at solving its nonlinear, time-varying, large delay and other characteristics. Depending on limit circulating method, accomplish designing fuzzy PID controller with auto-tuning capabilities. Thus, the system can tune PID parameters on line automatically. Simulation results show that the fuzzy PID controller has the feature of low overshoot, short settling time and high accuracy.Finally, set up an experimental platform for circulating chiller to test its main indicators. According to results, the temperature control stability of high-precision circulating chiller developed is better than ±0.01℃; peak cooling power is 1k W; temperature control range is 16℃~26℃, control resolution is betrer than 0.005℃, and has strong robustness. These indicators all reach predetermined specifications, and meet project requirements well.