New Pairs of Inks and Papers for Photolithography, Microcontact Printing, and Scanning Probe Nanolithography

Abstract

Currently, there is considerable interest in producing patterned metallic structures with reduced dimensions for use in technologies such as ultra large scale integration (ULSI) device fabrication, nanoelectromechanical systems (NEMS), and arrayed nanosensors, without sacrificing throughput or cost effectiveness. Research in our laboratory has focused on the preparation of precious metal thin films on semiconductor substrates via electroless deposition. This method provides for the facile interfacing of metal nanoparticles with a group (IV) and III-IV compound semiconductor surfaces. Morphologically complex films composed of gold, platinum, and palladium nanoparticles have been prepared as a result of the immersion of germanium and gallium arsenide substrates into dilute, aqueous solutions of tetrachloraurate (III), tetrachloroplatinate (II), and tetrachloropalladate (II), respectively. Continuous metallic films form spontaneously under ambient conditions, in the absence of a fluoride source or an externally applied current. This facile electroless deposition methodology provides an alternative to complex and expensive vacuum methods of metallization, yet allows for the preparation of both thin and thick nanostructured films with control over surface morphology and deposition rate. Furthermore, precious metal films prepared in this way exhibit excellent adhesion to the underlying semiconductor substrate. The resultant films were characterized utilizing scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and scanning probe microscopy (SPM). In order to apply this novel metallization method toward the development of useful technologies, patterning utilizing photolithography, microcontact printing (μCP), and scanning probe nanolithography (SPN) has been demonstrated.