Adhesion in multi-layer thin film structures was measured using the four-point bend technique. The investigation primarily focused on layers found in the backside metalization processes of Power MOSFETs (typically in a DMOSFET or U-MOSFET structure). Variation in metal layer and substrate condition produced changes in the adhesion behavior of the systems of interest. Pt, Cu, and Ti metals were applied to Si and SiO2 surfaces with various roughnesses in order to establish the relative contributions of surface chemistry and roughness variation. G values ranging from 2 – 100 J/m2 were measured and it was found that variation in surface chemistry has a larger impact than roughness on the adhesion strength of the systems investigated. The four-point bend adhesion test was determined to be adequate for the measurement of weak to intermediate adhesion of metals on Si wafers with RMS roughness values on the order of the metal film thickness.

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 highvolume 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.