Mixed-signal Chip Yield Problems Under The 0.11-micron Process

Compared with0.18pm process,0.13μm tech-node process can reduce chip size by50%and has better performance as well. The0.11pm tech-node process can reduce chip size by more than20%compared with0.13pm process while keeping the same device performance as the0.13μm process. Therefore,0.11μm process is a relatively advanced technology with the advantages of high integration and low cost. This thesis deals with the yield loss issue of operational current lower than spec in wafer bottom special pattern area on0.11μm mixed signal product. The thesis consists of five chapters. Chapter1is the review of yield concept in semiconductor manufacture. We analyse the difference between0.11μm process and0.13μm process, and give an overview of0.11μm mixed signal product manufacture process in the2nd chapter. Chapter3describes the yield loss issue of operational current lower than spec in wafer bottom special pattern area on0.11μm mixed signal product. From DFA, EFA and PFA, we suspect the issue is caused by dual gate process abnormal, which induces the core device gate oxide thickness higher than target and operational current lower than spec. At the same time, we discuss the containment action to the impacted wafers and do reliability analysis on them. Chapter4follows with a detail discussion on the suspected loop and the experiments to verify the mechanism. The results show: adding one de-scum step post the DG-PH development can improve the uniformity of core device gate oxide thickness; yield is sensitive to DG-ET wet process. From the analysis, we build up the failure model and find the process improvement method from the experiment At last, chapter5concludes this thesis.After all the actions have been implemented, the yield of0.11μm mixed signal product can recover to the level before the problem happened. This research provides a significant lessen leant to not only0.11μm process but also0.13μm process, and it can help improve the process stability and enlarge process window. Moreover, the results obtained in this study can also be applicable to the more advanced technologies, such as90nm or65/55nm, etc.