Study On EWMA Controller With Variable Gain

For the lack of in-situ measurements of the product qualities of interest, theimplementation of real-time process control in discrete process extrame in semiconductormanufacturing have been limited. The Run-to-Run control was proposed that update theprocess recipe by use the historical process data. Run-to-Run control is a compromisebetween statistical process control and real-time control, it providers a framwork toenhance product quality and overall equipment effectiveness. Because the minimumfeature size of the integrate circuit in the semiconductor manufacturing industry isdecrease too quickly that the traditional control strategy could not ensure the qualities ofthe products, so the Run-to-Run control is got more attention by semiconductor factoryand control engineers. The main works of this thesis are as follows.In the first chapter, the background of the Run-to-Run control in semiconductormanufacturing is introduced and the history of Run-to-Run control development isreviewed. After these, conclude the common structure of Run-to-Run control. Thenintroduce the state-of-the-art of the research and application of Run-to-Run control.The exponentially weighted moving average (EWMA) controllers are only suitablefor linear processes, which is a main weakness when treating nonlinear problem. Hence,in chapter three, an adaptive EWMA controller (named VG-EWMA) with a Varing Gainof process model is proposed. Compared to traditional EWMA controller, theVG-EWMA controller update both the intercept and the gain of the model, and canachieve better performance when applying to nonlinear processes.CMP (chemical mechanical planarization) is an important process in semiconductormanufacturing. In chapter four, the CMP process is used as simulation platform, thesimulation results show that the proposed VG-EWMA is better than traditional EWMAwhen the process is unlinear.In chapter five, a Run-to-Run control softwere is developed for the purpose ofpotential industrial applicaion. We introduced the framework of the software and therealization of each component. The virtual effect of the software is also included.The thesis concludes with a summary. We prospect both algorithm improvementsand practical applications of run-to-run control.