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Development of Virtual Metrology Models in Semiconductor Manufacturing Using Genetic Algorithm and Kernel Partial Least Squares Regression  

Kim, Bo-Keon (Memory Division, Samsung Electronics)
Yum, Bong-Jin (Department of Industrial and System Engineering, KAIST)
Publication Information
IE interfaces / v.23, no.3, 2010 , pp. 229-238 More about this Journal
Abstract
Virtual metrology (VM), a critical component of semiconductor manufacturing, is an efficient way of assessing the quality of wafers not actually measured. This is done based on a model between equipment sensor data (obtained for all wafers) and the quality characteristics of wafers actually measured. This paper considers principal component regression (PCR), partial least squares regression (PLSR), kernel PCR (KPCR), and kernel PLSR (KPLSR) as VM models. For each regression model, two cases are considered. One utilizes all explanatory variables in developing a model, and the other selects significant variables using the genetic algorithm (GA). The prediction performances of 8 regression models are compared for the short- and long-term etch process data. It is found among others that the GA-KPLSR model performs best for both types of data. Especially, its prediction ability is within the requirement for the short-term data implying that it can be used to implement VM for real etch processes.
Keywords
virtual metrology; genetic algorithm; kernel partial least squares regression;
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