Wear comparison of critical dimension-atomic force microscopy tips
Ndubuisi G. Orji, Ronald G. Dixson, Ernesto Lopez, Bernd Imer
Nanoscale wear affects the performance of atomic force microscopy (AFM)-based measurements for all applications including process control, nanoelectronics characterization and topography measurements. As such, methods to prevent or reduce AFM tip wear is an area of active research. However, most of the prior work was on conventional AFM rather than critical dimension atomic force microscopy- used in integrated circuit metrology. Hence, less is known about critical dimension atomic force microscope (CD-AFM) tip-wear than other types of tips. Given that tip-wear directly affect the accuracy of dimensional measurements, basic wear information for CD-AFM tips are needed. To help fill in this gap, we evaluated the wear performance of electron beam deposited tips, a relatively new class of CD-AFM tips. Using a continuous scanning strategy, we evaluated their overall wear rate and tip lifetime and compared the results with those from silicon-based CD-AFM tips. The results show improved tip lifetime of as much as a factor of five and reduced wear rates of more than 17 times. Such improvements in wear rate means less measurement variability and lower cost.