Application of the low-loss scanning electron microscope image to integrated circuit technology - Part II - Chemically-mechanically planarized samples

Chemical-mechanical planarization (CMP) is a process that gives a flat surf ace on a silicon wafer by removing material from above a chosen level. This flat surface must then be reviewed (typically using a laser) and inspected for scratches and other topographic defects. This inspection has been done using both the atomic force microscope (AFM) and the scanning electron mic roscope (SEM), each of which has its own advantages and disadvantages. In t his study, the low-loss electron (LLE) method in the SEM was applied to CMP samples at close to a right angle to the beam. The LLEs show shallower top ographic defects more clearly than it is possible with the secondary electr on (SE) imaging method. These images were then calibrated and compared with those obtained using the AFM, showing the value of both methods. It is bel ieved that the next step is to examine such samples at a right angle to the beam in the SEM using the magnetically filtered LLE imaging method.