Total solution of line CD measurement quality control and application of statistical methods for CDSEM line CD measurement stability

The line CD measurement stability has to be evaluated in addition to pitch CD in sub-130 nm node. Regression SPC has been conducted for evaluating CDSEM with the linear growth of the control wafer, that is constructed to minimize the well-know carry-over effect. Also, the P-value is applied in model diagnostic, Exponentially Weighted Moving Average (EWMA) control chart is employed to detect the small shift of measurement process. Eventually, to definitely quantify the CDSEM line width measurement variation and also to indicate how measurement variation contribute the process variation(Cp) by means of Regression SPC.