Method and system of compressing raw fabrication data for fault determination

A method of compressing raw data representing an operational parameter of a semiconductor manufacturing equipment for fault determination, comprising the steps of:

• inputting into a signal convertor a collection of raw data points representing operational parameters of the semiconductor manufacturing equipment within a predetermined time period;
• obtaining an approximation of the raw data points with a Fourier series by the signal converter;
• computing the Fourier coefficients and the residuals between each of the raw data points and the corresponding predicted values by the Fourier series;
• determining if the residuals exceed an error threshold;
• and
• if none of the residual exceeds the error threshold, recording and storing in a data storage device the Fourier coefficients as the compressed data;
• if the corresponding residual exceeds the error threshold, recording in the data storage device the raw data point as abnormal data point before recording and storing the Fourier coefficients and the abnormal data point as the compressed data.