reaction occurs at the surface of the silicon. In this example, the width of the line depends on the number times the line is traced.

FIGURE 4-33 Example of voltage generated lithography pattern in an AFM. At the bottom is an example of anodic oxidation with an AFM. The lines are 50 nm wide.

The force of the probe on the surface can be increased while scanning with an AFM. If the sample's surface is softer than the probe, the probe will scratch the surface. Figure 4-34 shows an image of a pattern drawn in the surface of photo resist with an AFM.

FIGURE 4-34 An AFM probe can scratch a surface. The image at the bottom shows a pattern with nm features created by scratching.

Chemicals may be deposited directly from an AFM probe onto a surface¹², see Figure 4-35. The chemicals may flow by diffusion from the surface of a probe. Alternatively, the chemicals may be deposited on a surface from a hole fabricated in the probe. It has already been demonstrated that several types of chemicals may be deposited on a surface. Examples include thiols on gold, proteins, and metals.