Patent ID: 7062411

Claim:
A method of fault detection in a semiconductor substrate chamber processing tool having at least one sensor providing a plurality of data sensitive to tool-state and process-state changes, the method comprising the steps of: (a) establishing a set of vectors representing the magnitude and direction of the deviation of sensor data from nominal values for a state of the tool under a fault condition, said fault condition generating a recordable fault fingerprint, (b) performing step (a) a plurality of times for a plurality of different fault conditions respectively and storing the resultant sets of vectors in a fault fingerprint library, the fault fingerprints being substantially invariant across different tools built to the same nominal specification and running the same nominal process, (c) determining a set of vectors representing the deviation of sensor data from nominal values for the present state of the tool, and (d) detecting a fault based on a comparison of the present state set of vectors with at least one fault fingerprint in the fault fingerprint library.