Nanolithography of positive and negative structures by scanning probe microscopy using force modulation

In the semiconductor industry, structures down to 100 nm may be created by conventional mask lithography. To overcome this technological barrier, new tools have to be developed. Although electron-beam lithography can generate structures in this geometrical dimension, its disadvantages complicate a routine use. Scanning probe microscopies, on the other hand, are promising tools for the fabrication of nanometer sizes structures which are independent of these constraints. Several applications of scanning probe microscopes to nanolithography are reported. Their main disadvantages are their limitation to specific substrates like Silicon or Titanium, special resist like monolayer inorganic materials or low resist thicknesses not suitable for industrial use. We present a scanning probe technique which is able to create positive and negative structures on a conventional electron beam resist in development liquid. The tip of the scanning probe microscope is scanned in direct contact to the resist surface under a defined load force. With this technique we were able to create arbitrary 3D structures with widths between 80 nm and 80 micrometers and depths between 5 nm and 0.5 micrometers in e-beam resists. The main advantage of the presented technique is the fabrication of oblique structures in one step which cannot be done by any other lithography technique.