Patent ID: 7966138

Claim:
An apparatus for creating a test pattern and calculating a fault coverage, and bridge fault residual ratio or simply total adjacent wiring length of undetected bridge faults, comprising: a bridging fault voltage calculation section that creates bridging fault voltage information indicating a relationship between logical values of input signals of a plurality of cells and voltages of bridging points assumed on the wires derived from output terminals of the plurality of cells and including supply current value information; a logical threshold calculation section that creates logical threshold information by calculating logical thresholds of input terminals of the plurality of cells; a bridging fault information extraction section that extracts bridging fault information including signal information on an adjacent wire pair whose inter-wire distance is within a predetermined short distance range where bridge faults occur with a probability, a wiring length of the adjacent wire pair, information on an input terminal of a drive cell that drives the adjacent wire pair and information on an input terminal of a reception cell to which a signal propagating to the adjacent wire pair is inputted, from layout information of a semiconductor integrated circuit; a detection limit resistance value calculation section that calculates a detection limit resistance value based on a voltage of the bridging point included in the bridging fault voltage information and the supply current value information and a distribution of logical thresholds of a cell included in the logical threshold information and to which the bridging point is connected, adds information on the detection limit resistance value to the bridging fault voltage information and creates extended bridging fault voltage information; a bridging fault list creation section that creates a bridging fault list including a bridging fault type determined by a relationship between a voltage of the bridging point and logical threshold of the input terminal of the reception cell using the bridging fault information, the logical threshold information and the extended bridging fault voltage information; a test pattern creation section that creates a test pattern for detecting bridging faults in the adjacent wire pair using the bridging fault list, judges whether the bridging faults included in the bridging fault list can be detected according to the test pattern and creates fault detection information; and a fault coverage calculation section that calculates a bridging fault coverage and a bridging fault residual ratio of the test pattern weighted with an integral value of a bridging fault resistance value distribution in a detection resistance area according to the test pattern based on the detection limit resistance value and the wiring length using bridging fault occurrence rate information including the fault detection information and bridging fault resistance value distribution information.