Patent ID: 7283918

Claim:
A fault analyzing apparatus of a semiconductor integrated circuit comprising: a test and detected fault database storing a test vector of an IDDQ test and detected and undetected faults on each measuring point of the test vector; a fault related information extracting portion extracting, as fault related information, a fault and information about a driving circuit of the fault based on layout information of the semiconductor integrated circuit and logical connection information of the semiconductor integrated circuit; an operation analyzing portion analyzing an operation of the semiconductor integrated circuit based on the logical connection information, operation information of the driving circuit, the test vector and the fault related information and obtaining a signal value of a portion corresponding to each fault on each measuring point and an input value of the driving circuit in case that the fault does not exists; an IDDQ test result database storing a pass/fail result on the measuring point in the IDDQ test, a measured value and at least a difference between the measured value on a failed measuring point and a measured estimation value in a case that the semiconductor integrated circuit does not include the fault; a fault candidate extracting portion extracting fault candidates from detected faults on each measuring point based on the pass/fail result on the measuring point which is stored in the IDDQ test result database and the detected fault on the measuring point which is stored in the test and detected fault database; a variation database storing at least a variation corresponding to an input value of an IDDQ value in case that a fault is included with respect to a case in which the fault is not included for each circuit for driving the fault candidate or coefficient data constituting an equation for calculating the variation; and a calculating and deciding portion calculating an estimated calculation value to be a difference of the IDDQ value in a case that a fault candidate is included with respect to the case that the fault on the failed measuring point is not included based on an input value of the circuit for driving the fault candidate on the failed measuring point which is calculated by the operation analyzing portion and the variation database, and comparing the estimated calculation value to be the difference with a difference between the measured value on the failed measuring point which is stored in the IDDQ test result database and the measured estimation value, thereby deciding whether the fault candidate is the fault corresponding to the defective portion or not.