Test and diagnosis of open defects in digital CMOS integrated circuits

Open defects are breaks or imperfections in circuit connections. Effective testing and precise diagnosis for open defects are important because the former ensures IC quality and the latter helps to improve the yield. This dissertation presents effective test and precise diagnosis techniques for three major types of open defects: tunneling opens, resistive opens and stuck opens.; A tunneling open defect is a thin open that allows electrons and holes to tunnel through it. Tunneling opens are difficult to detect because they can pass tests at nominal voltage. In this dissertation, Very-Low Voltage (VLV) testing is shown to be effective for detecting tunneling open defects. It is also demonstrated that some tunneling open defects can be detected by I_DDQ(t) testing, in which multiple quiescent power supply current measurements are made without changing test patterns. A pattern selection algorithm for I_DDQ(t) testing is developed to minimize the I _DDQ(t) test time.; A precise diagnosis technique for tunneling open defects is shown. This technique consists of both VLV and I_DDQ(t) diagnosis. By combining these two pieces of information, the diagnosis precision is enhanced. This diagnosis is demonstrated by both simulations and experiments.; A resistive open defect is an imperfect circuit connection that can be modeled as a defect resistor between two circuit nodes that should be connected. Detecting resistive open defects can be challenging because some resistive open defects can escape tests at nominal voltage or at room temperature. This dissertation shows that delay testing is effective for detecting resistive open defects. It also shows that the optimal test voltage and test temperature depend on the defect location and defect material respectively.; A stuck-open defect is a complete break (no current flow) between two circuit nodes that should be connected. Conventional single stuck-at fault diagnosis cannot precisely diagnose stuck opens because the test results of stuck-open chips depend on the sequence of test patterns. This dissertation presents a precise diagnosis procedure for stuck-open defects. This diagnosis technique is capable of using two fault models at the same time. A modified version of this diagnosis is used to diagnose resistive opens.