The locally remove strategy begins with covering the entire surface with a SAM. Then individual SAM molecules are removed from locations where the deposition of nanostructures is not desired. The result is the same as in the locally attract strategy, the difference being in the way this is achieved. The major techniques that use this strategy are:
* Scanning tunneling microscope
:The scanning tunneling microscope can remove SAM molecules in many different ways. The first is to remove them mechanically by dragging the tip across the substrate surface. This is not the most desired technique as these tips are expensive and dragging them causes a lot of wear and reduction of the tip quality. The second way is to degrade or desorb the SAM molecules by shooting them with an electron beam. The scanning tunneling microscope can also remove SAMs by field desorption and field enhanced surface diffusion.
* Atomic force microscope
:The most common use of this technique is to remove the SAM molecules in a process called shaving, where the atomic force microscope tip is dragged along the surface mechanically removing the molecules. An atomic force microscope can also remove SAM molecules by local oxidation nanolithography.
* Ultraviolet irradiation
:In this process, UV light is projected onto the surface with a SAM through a pattern of apertures in a chromium film. This leads to photo oxidation of the SAM molecules. These can then be washed away in a polar solvent. This process has 100 nm resolutions and requires exposure time of 15–20 minutes.