H. N. Lin, C. H. Wang, .. K. .. L. Lin, W. S. Yang, .. C. J. Chen, Taiwan Semiconductor Manufacturing Company Ltd, Kaohsiung County, Taiwan

Summary: OBIRCH (Optical Beam Induce Resistance Change) is one popular method for isolating short failures for process development test structures on 130nm and 110nm technology. As technology progresses and the width of metal line shrinks, we still apply this method for the failure analysis of 90nm metal line. However, we have some issues for OBIRCH inspection on 90nm technology. The OBIRCH signals of samples were so weak, even nothing or just noise. It becomes so difficult to locate the defect by OBIRCH. The weak OBIRCH signal is caused by the shrinking in metal line and metal spacing which induce the increase of resistance. We found two solutions for isolating the failure. The first method is to calculate the position of defect by electrical measurement; the second method is to enhance the OBIRCH signal for accurately localizing defect using circuit modification. These two methods can successfully locate the defect, and help us to improve the efficiency of physical failure analysis. The paper will demonstrate the details of these two techniques.