Regardless of the method of initiating the surface change there are two basic types of lithography possible with the AFM; they are a vector and dot mode, ( see Figure 4-31 ).

The patterns that are created on a surface with an AFM in lithography mode are typically generated from an input file, typically a .bmp or .jpg file. After inputting the pattern, the software generates the motions required for the probe to create the pattern on a surface. Associated with the pattern is the method for writing, the writing speed, and the mode of writing. Figure 4-32 illustrates a typical software input window. In general, the resolution of AFM lithography techniques is proportional to the diameter of the probe used for generating the pattern.

FIGURE 4-32 AFM lithography software inputs the pattern to draw and allows selection of the type of patterning.

The AFM affords one of the most economical platforms for creating nanoscale features on a surface. The versatility of the tool for lithography is substantial. However, there is one major drawback; the scan rates of an AFM are slow. Generating a pattern can be very time consuming with an AFM.

In 1989 it was demonstrated that the localized current from a small probe, as in a scanning tunneling microscope, can cause changes in a material's surface¹¹. In an AFM, current flowing from the apex of the probe to the sample can cause chemical reactions at the surface.

The most common example of AFM lithography using a potential between a probe and surface is anodic oxidation. Typically a potential is placed between a probe and a silicon wafer (see Figure 4-33). An electrochemical