The implementation of AFM for process monitoring and metrology in trench MOSFET device manufacturing

In this investigation the implementation of AFM as a tool for process control as well as a metrology tool for characterizing trench MOSFET devices in a manufacturing environment is examined. In particular this study focuses on three major issues surrounding the implementation of AFM into a high-volume manufacturing environment for process control. First, factors influencing automated data collection are reviewed including scan calibration, alignment identification, alignment issues, and SPC optimization. Second, the critical features of AFM tip selection, behavior, and capability are discussed. Finally, AFM monitoring capability for features within the trench, such as recessed polysilicon and ILD planarization, is evaluated. The AFM is shown to be effective at evaluating depth and surface topography issues. However, the AFM´s ability to monitor critical dimension (CD) openings is shown to be very limited.