Modelling and controlling of critical dimension in semiconductor manufacturing
by Shichang Du, Lifeng Xi, Jiwen Sun, Ershun Pan
International Journal of Materials and Structural Integrity (IJMSI), Vol. 4, No. 1, 2010

Abstract: As critical dimension (CD) in semiconductor device is always shrinking, it brings us many difficulties to control it. Since lithography and etch are all pivotal steps of CD, it is critical to identify, manage and minimise the major sources of variation of lithography and etch in the presence of different disturbances. Therefore, in this paper, two linear model predictive controllers (LMPCs) are formulated – the lithography CD controller and the etch CD controller on the basis of presenting a comprehensive study of the advantages and disadvantages of current methods of controlling of CD. The lithography CD controller manipulates multiple inputs – dose and focus, the etch CD controller manipulates etch time and Kalman filtering technologies are used to estimate state variables. The simulations of the two CD controllers designed are performed considering different types of disturbances and a comparison of performance of LMPCs and exponentially weighted moving average (EWMA) is presented. The results show that there is a significant reduction of the effect of the disturbances on CD and the two controllers are flexible and robust controllers with superior control ability to control CD.

Online publication date: Sun, 04-Apr-2010

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