Browsing by Author "Kincal, S."

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    Impact of pad conditioning on thickness profile control in chemical mechanical planarization
    (Springer Science+Business Media, 2013-01) Kincal, S.; Başım, Gül Bahar; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar
    Chemical mechanical planarization (CMP) has been proven to be the best method to achieve within-wafer and within-die uniformity for multilevel metallization. Decreasing device dimensions and increasing wafer sizes continuously demand better planarization, which necessitates better understanding of all the variables of the CMP process. A recently highlighted critical factor, pad conditioning, affects the pad surface profile and consequently the wafer profile; in addition, it reduces defects by refreshing the pad surface during polishing. This work demonstrates the changes in the postpolish wafer profile as a function of pad wear. It also introduces a wafer material removal rate profile model based on the locally relevant Preston equation by estimating the pad thickness profile as a function of polishing time. The result is a dynamic predictor of how the wafer removal rate profile shifts as the pad ages. The model helps fine-tune the pad conditioner operating characteristics without the requirement for costly and lengthy experiments. The accuracy of the model is demonstrated by experiments as well as data from a real production line. Both experimental data and simulations indicate that the smaller conditioning disk size and extended conditioning sweep range help improve the post-CMP wafer planarization. However, the defectivity tends to increase when the conditioning disk sweeps out of the pad radius; hence, the pad conditioning needs to be designed by considering the specific requirements of the CMP process conducted. The presented model predicts the process outcomes without requiring detailed experimentation.
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    A model of chemical mechanical planarization to predict impact of pad conditioning on process performance
    (Cambridge University Press, 2012) Başım, Gül Bahar; Kincal, S.; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar
    This study presents an effort to couple a wafer removal rate profile model based on the locally relevant Preston equation to the change in pad thickness profile which reflects to post polish profile of the wafers after Chemical Mechanical Planarization. The result is a dynamic predictor of how the wafer removal rate profile shifts as the pad ages. These predictions can be used to fine tune the conditioner operating characteristics without having to carry out high cost and time consuming experiments. The accuracy of the predictions is demonstrated by individual confirmation experiments in addition to the evaluation of the defectivity performance with the varied pad conditioning profiles.