Wafer scale integration of catalyst dots into nonplanar microsystems

In order to successfully integrate bottom-up fabricated nanostructures such as carbon nanotubes or silicon, germanium, or III-V nanowires into microelectromechanical systems on a wafer scale, reliable ways of integrating catalyst dots are needed. Here, four methods for integrating sub-100-nm diameter nickel catalyst dots on a wafer scale are presented and compared. Three of the methods are based on a p-Si layer utilized as an in situ mask, an encapsulating layer, and a sacrificial window mask, respectively. All methods enable precise positioning of nickel catalyst dots at the end of a microcantilever, while avoiding contamination of the used cleanroom process equipment. The methods are suitable for fabrication of scanning probe tips and nanoelectrodes for advanced characterization probes.