Subject contact-mode

Since fmm is a contact mode technique it subjects the sample s surface to possibly destructive lateral forces as the tip scans. A less destructive alternative is to operate in the tapping-mode regime (46). Changes in mechanical properties... 

In the range Ijum to 100 nm of the surface, the tip is subjected to electrostatic forces that can be either repulsive or attractive depending on the surface. Within 100 nm, the tip will experience capillary attractive forces. When operating in air, this is due to surface water. Although this is not the problem that it is in contact mode (see Section 3.3.3), these forces do affect the cantilever oscillation. Figure 3.31 shows the amplitude and phase signal (as [90 - ]°) in a frequency sweep of a cantilever far from the surface, and then near to but not contacting the surface. Far from the surface, 200/rm above it, Q is 640 and the resonant frequency is... 

Whether CMP occurs as Hertzian indentation or fluid-based wear is not clear and has been the subject of some debate. The difference between the two wear modes is in the slurry fluid layer between the pad and wafer. As discussed in Section 4.2, if the fluid layer is not continuous, then pad-wafer contact occurs. Note, however, that the pad does not contact the wafer surface directly, but rather the pad presses abrasive particles against the surface. In such instances, the pad will drag the abrasives across the surface, resulting in Hertzian indentation. 

Environmental stress cracking is considered to be the most fi-equent mode of failure of plastic materials.It was estimated in 1996 that 20% of plastics failed because of environmental stress cracking. By environmental stress cracking, we understand a failure in which materials in contact with a fluid are subjected to stress. " It is quite difficult to simulate environmental stress cracking in the labo-... 

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