A Method Of Air Temperature Control In Lithography

Lithography is very important equipment in the semiconductor manufacturing industry, its performance directly determines the characteristics of the production line integrated circuit. The line width and the overlay accuracy is the most important performance parameters in lithography, their influence is mainly affected by the internal properties of the lithography, and the internal air temperature lithography machine is one of most important factors affecting the performance, therefore, the temperature of the air control technology is one of the lithography must solve the technology. Research shows that to ensure the imaging quality of lithography, air temperature fluctuation range lithography internal should be controlled at0.05℃.Lithography machine internal volume and quality is large and it is not convenient to direct object air temperature control, The temperature of the air in the traditional methods of control in the process of the controlled object air temperature is approximately equal to the cooling medium; the air temperature control system only needs to detect the cooling medium value. This method is feasible and low system requirements in accuracy, but it lacks the control algorithm object to the target and the feedback loop, high precision temperature control is difficult to achieve the range of0.05℃. The air temperature control system in order to enter the internal air temperature control object lithography, cooling medium for secondary controlled object, including the temperature control system of the main controller, the temperature of the air collection system, temperature control system, air, is constituted by the internal cavity of lithography object closed-loop feedback control system. Then under the system, electric and control algorithm are design. Such as inverter, pumps and main circuits, PLC, PID and communication algorithm. All of them make air temperature control system be a complete device. Finally, simulation of lithography machine working condition was established to simulate the temperature control experiment platform, lithography internal cavity as the controlled object of the experimental study of the air temperature control system. The final test results:the air temperature fluctuation is less than0.05℃, and has good adjustment curve.