Development of Robust AFM Technique for Roughness and Morphology Characterization of Gate Stack Thin Films

Surface roughness and grain morphology are among the critical parameters to be monitored during IC wafer processing, because, with the shrinking device critical dimensions, such parameters become more influential in device performance and manufacturing yield. Among the surface roughness and morphology characterization tools, AFM (atomic force microscope) is unmatched in its combination of height profiling sensitivity and lateral resolution. However, the major problem with AFM is fast tip wear, the effects of which are greatest for thin films deposited in front‐end processing because of the minute surface feature sizes and high lateral resolution required for their imaging. To overcome this drawback, the major factors (tip oscillation amplitude and frequency) that influence the performance of AFM operated in the popular tapping mode were studied. The understanding of the effects of these factors allowed us to device a robust method to operate the AFM in a stable attractive tip‐to‐sample interaction regime ...