Methods of error detection in fabrication processes

A method for stopping semiconductor fabrication, comprising:

• obtaining a plurality of sets of measurements wherein each set of measurements comprises a measurement of each of one or more parameters from each of one or more semiconductor wafers;
• for a set of measurements, creating a measurement vector, creating one or more correlation matrixes comprising correlations between measurements of parameters of a semiconductor wafer, creating one or more autocorrelation matrixes comprising correlations of a parameter between a pair of the one or more semiconductor wafers, creating a combined matrix by combining the one or more correlation matrixes and the one or more autocorrelation matrixes, obtaining a T2 value from the measurement vector and the combined matrix, obtaining a chi-square distribution value comprising a degrees of freedom value and a preselected confidence value wherein the degrees of freedom value comprises the number of measurements in the measurement vector, and creating a figure of merit wherein the figure of merit is the square root of the ratio of the T2 value to the chi-square distribution value;
• and
• stopping a semiconductor wafer fabrication tool if a figure of merit from one or more measurement sets exceeds a critical value.