US Patent 7431970 - Rewritable polymer nanolithography

http://www.freepatentsonline.com/7431970.html

IBM's Millipede system is one of a few designs for using arrays of atomic force microscope tips for nanoscale memory applications. This patent from the Air Force teaches a rewritable version based on thermal heating in which no polymer is removed during tip induced heating and using anneal processes for erasure of data. Claim 1 reads:

1. A polymer nanolithography method, comprising the steps of:

providing an atomic force microscope;

providing a conductive cantilever tip within said atomic force microscope;

providing a thin polymer film mounted upon a conductive wafer;

installing said thin polymer film within said atomic force microscope;

establishing a relative humidity within said atomic force microscope between about 10 to about 70 percent;

setting an initial tip-surface distance by applying a voltage to said cantilever tip such that no mechanical deformation of the surface of said polymer film during scanning occurs; and,

forming nanoscale features upon said polymer by selectively varying said voltage applied to said cantilever tip to effect a desired localized softening of attoliters of said polymer by Joule heating.