Quickly And Accurately Localizing Defect Techniques And Experiments Study In Integrated Circuit Failure Analysis

In IC failure analysis, it is difficult to localize the hard defects quickly and precisely only by one defect localization technique on the complicated functional failed ICs stimulated by the hard defects. The functional test result on an IC is depended on temperature or other test conditions due to a soft defect, so it is more difficult to localize the soft defect quickly and precisely.In this paper, the typical defects and their influences on ICs are stated. The main defect localization techniques are introduced. The four important defect localization techniques, Photon Emission Microscopy(PEM), Optical Beam Induced Resistance Change(OBIRCH), Schematic/layout study technique, Microprobing technique, are studied, and then an optimal process method is proposed by combination their advantages together for quickly and precisely localizing some typical hard defects. The failed circuit can be localized quickly and then the hard defect is nailed down precisely by this method. The experiments show this method is effective to localize some typical hard defects. It takes at least two weeks to localize a hard defect using only one defect localization technique, and the success rate is about 60%. However, the average cycle time of the defect localization is shortened to five days by the optimal process method, and the success rate is up to 95%. However, the soft defects could not be localized easily by the optical process method. The soft defect could be localized quickly and precisely on both digital ICs and analog and mixed signals ICs only by OBIRCH technique on hand, when the IC test system is synchronized with the laser scanning module of OBIRCH by the dynamic synchronization method, and the abnormal variations of the different analog and mixed signal parameters are converted to digital flags on behalf of the test results. The average soft defect localization time is three days.There are three innovation points in this paper:1、 An optimal process method is proposed to quickly and precisely localize thehard defects on the functional failed ICs stimulated by the hard defects. Thismethod combines all advantages together of four important defect localizationtechniques: PEM, OBIRCH, Schematic/layout study technique andMicroprobing technique. The failed circuit can be localized quickly and thenthe hard defect is nailed down precisely by this method. 2、 For the soft defects on digital ICs, the dynamic syncronization method isproposed to dynamically synchronize the IC test system and OBIRCH laserscanning system. So the soft defects could be located quickly and preciselyonly by the OBIRCH technique on hand. 3、 For the soft defects on analog and mixed signal ICs, the abnormal variationsof the different analog and mixed signal parameters are converted to digitalflags on behalf of the test results, so the digital flags can be processed byOBIRCH easily and match the needs of dynamic synchronization. The softdefects on analog and mixed signal ICs could be localized quickly andprecisely by this method.