Creating Diamond-Like-Carbon (DLC) Templates Using Atomic Force Microscopy

Pattern generation on the micro- and nano-scale is a vital ingredient in a vast variety of applications including biosensors and array devices. Current technologies are generally macroscopically-based, however a considerable increase in demand upon down-sizing must result in enabling meso/nanoscopic manipulation. Soft lithography is now routinely utilised in various applications with particular attention and importance placed on pattern transfer onto polymeric materials via the creation of masters. These are now fabricated using a number of techniques, all capable of producing well-defined surface topographies. The microelectronic industry utilises methods such as photolithography in order to fabricate such master templates at the micron scale. Various polymers can be used to transfer patterns. One of the most widely used is polydimethylsiloxane (PDMS). The elastomer is chemically resistant, has a low surface energy and readily conforms to different surface topographies. Obtaining a master is the limiting factor in the production of PDMS replicas. The use of diamond-like-carbon (DLC) as a master template is demonstrated in this study. PDMS micro/nano stamps and 3 dimensional PDMS structures have been created and routinely reproduced. Intricate surface relief patterns are formed on the DLC surface from lithographic techniques by atomic force microscopy (AFM) operated in the electrical conductivity mode. The mode induces oxidation on a DLC surface creating patterns in the tens of nm. An example of a lithographic pattern created on a DLC surface by this method is shown in the topographical image. The template shown was then coated with a layer of PDMS and thus used as a master. The resultant fabricated PDMS stamp is shown. The relief of the stamp correlates very well with the dimensions of the DLC master.