Experiment And Research On Control System Of Wafer Inspection Stage

The chemical and particle pollution detection of Silicon surface is an important process of IC industrial chain, its detection precision has a significant influence on the efficiency and quality of large scale integrated circuit manufacturing. At present, there is a gap between the domestic technology and the technology of world advanced level on production line for 300 mm diameter silicon wafer. So it is significant to improve the level of production of IC industry in China that developing a high-precision 300 mm platform for wafer testing.In this thesis, we first determine the wafer testing platform structure and movement performance requirements by analyzing the principle of silicon pollution detection system, and then we design the hardware part and software part of the control system of this platform according to the requirements. In the process of debugging we found that the movement of the rotation axis brings a periodic disturbance on the horizontal axis, which makes the horizontal axis fluctuate in the running at a constant speed. Because of this the repeat rate and omission rate of pollution detection increase. So it becomes an important problem in the research work to improve the ability of disturbance rejection of the horizontal axis.This article emphatically carries on the design and experimental analysis of horizontal axis servo control loop. In the first we establish the mathematical model of permanent magnet synchronous linear motor current loop and design the loop controller, eventually we simplify the loop as a linear amplification, which simplifies the design complexity of the speed loop and position loop. After identifying the open-loop transfer function of the speed loop, we adopts the quadratic integral sliding mode control and repetitive control strategy as speed loop control policy to suppress the disturbance brought by the rotation axis. In simulation experiment, we have some comparison with these two strategy and PI strategy on their control effect and find that the repetitive control method is most effective in terms of disturbance rejection and sliding mode control method is followed, but the repetitive control is weak in terms of response speed.Then this thesis adopts position trajectory generator method and double feedforward PI control strategy in the design of the position loop, the use of these two methods improves the horizontal position control accuracy and response speed.At last, this thesis tests three-axis joint motion precision of the silicon solution detection bench, and then makes evaluation of repeating scan rate and omission rate of the silicon wafer test platform used in the wafer solution detection system, proving that the three axis control method is effective, especially the horizontal axis servo control strategy is effective. So the platform meets the design requirements and makes the distance between our country and the world's advanced level close.