Patent ID: 7027947

Claim:
An integrated circuit testing method comprising: a reading step wherein circuit data is read out by a circuit data reading unit; a path cut step wherein a path cut point is selected from a target circuit and a state is fixed by a path cut countermeasure unit; and an automatic test pattern generating step wherein test data to detect a delay failure with respect to the circuit whose path cut has been finished as a target is generated by an automatic test pattern generation unit, wherein said automatic test pattern generating step comprises: a narrowing step wherein an area including a sending FF group corresponding to failure presumption points, a receiving FF, and further, a preparation FF group that is one-stage precedent to said sending FF group is specified as a processing target circuit by a narrowing processing unit; a failure exciting step wherein states of failure excitation at sending time and receiving time which have an inverting relation such that the state changes from 0 to 1 in a leading failure and changes from 1 to 0 in a trailing failure are allocated to said failure presumption points by a failure exciting unit; a path activating step wherein states at the sending time and the receiving time for activating a propagating path of said failure are allocated to the residual preparation FFs and sending FFs by a failure propagating state setting unit; and a failure propagating step wherein, by an automatic test pattern generation control unit, a system clock is supplied as a sending clock to said sending FF, a change is given to a network from the sending FF and propagated, the system clock is supplied as a receiving clock to said receiving FF, and the network change is captured, thereby propagating a state for detecting the delay failure to a path between the sending FF and the receiving FF and generating a test pattern when the propagation succeeds, and further, in said path activating step, an allocation of a don't care X is permitted as a state for activating the propagating path of the failure, and in said failure propagating step, after the change in network, the state is transferred from the don't care X to an uncontrol value, thereby activating the propagating path of the failure.