Surface height variation

If the surface (i.e., the best fit plane) is in the x—y plane, and Z x,y) is the surface height variation (surface roughness) relative to that plane, the power spectral density is given by... 

In this system the AFM does not prevent collection of the microtomed sections, so TEM of the cut sections can be combined with AFM 3D imaging of the block. The image signal can come from surface height variations that arise from mechanical property fluctuations in the block, or the AFM mode can be set to be sensitive to the specimen stiffness directly (see Section 3.3.2). This system is thus applicable to polymer samples including blends and filled systems, as shown in Fig. 6.10 [181]. 

Fig. XVin-3. AFM image of DNA strands on mica. Lower figure image obtained in the contact mode under water. The contrast shown covers height variations in the range of 0-2 nm. Upper figure observed profile along the line A-A of the lower figure. (From S. N. Magnov and M.-H. Whangbo, Surface Analysis with STM and AFM, VCH, New Yoric, 1996.)...

Topography planarization differs in several respects from blanket wafer polishing. Topography height variations over the wafer surface induce variations in contact local pressure high areas have higher contact pressure, and low areas may see little or no contact pressure. At equilibrium, the integral of the contact pressure over the wafer surface must equal the applied load. 

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