In the introduction to micro-thermal analysis, contact mode atomic force (AFM) microscopy is explained. This can, of course, be carried out with a conventional AFM probe. There are variants of contact mode AFM that arise from different ways of moving the probe and detecting how it responds.

The schematic (left) illustrates force modulation mode where the tip is moved up and down, as it is rastered over the surface of the sample. This can be seen as a type of indentation measurement that can image the local compliance of the sample.

The schematic (right) illustrates lateral force imaging where, as the tip is rastered over the sample, its movement in the x direction is modulated and the response to this modulation (the twisting of the cantilever) is measured by the photodetector. This mode can be thought to image the frictional properties of the sample.

In both of these modes, the tip is at all times in contact with the sample.

Above are images of metal lines on a semiconductor. The lateral force image shows areas of high friction that correspond to low compliance in the modulated force image. In this way contamination on the device can be mapped.