Evolution of surface morphology of nano and micro structures during focused ion beam induced growth

We report on the morphological studies of C, Pt and W nanopillars fabricated by focused ion beam chemical vapor deposition (FIB-CVD) process. The pillars have large base size as compared to the tip and they exhibit a rough morphology with whisker like structures protruding out of the surface. The whiskers have thickness of about 100nm and their length varies upto 1μm. The dimensions of these protrusions depend on the location of the protrusions on the pillar surface and show a systematic variation and saturation of growth as a function of ion flux. The growth of protrusions has been explained on the basis of formation of crystalline seeds on the surface due to ion beam induced temperature rise and cracking of the precursor gas in the vicinity of the seeds due to the secondary ion and electron impact. Pillars having smooth surfaces can be achieved by milling the edges of these structures.