Fabrication and characterization of cobalt particles by ion-beam induced chemical vapor deposition (IBICVD)
Ko-Wei Lin*, Zhengang Zhang, and Takao Suzuki
Toyota Technological Institute, JP
Keywords: IBICVD, magnetic nanodots
Nanometer-sized patterned media has been of great interest in high density data storage application [1,2]. Different fabrication techniques have been studied with its unique physical properties of nanoscale features. Among these, ion-beam induced chemical vapor deposition (IBICVD) technique (Figure 1), combining three independently established techniques (computer-controlled, ion-beam, and CVD) in a single procedure has been proposed and investigated. In our previous work , fabrication of submicron-scale cobalt particles utilizing octacarbonyl dicobalt [Co2(CO)8] as Co precursor has been accomplished by IBICVD through vector scan rastering. The magnetic characterization by alternative gradient field magnetometer (AGFM) and by Lorentz TEM has shown that these IBICVD dots exhibit ferromagnetic properties . To explore size limitation, the arrays of Co dots deposited on a polished glassy carbon as well as on TEM grid were studied. The morphology of the fabricating Co dots was monitored in-situ by secondary electron microscopy of the focused ion beam (FIB) system. The topographic features and magnetic properties were characterized by using AFM and MFM, respectively. Results have shown that the shape and size of Co dots depends on the precursor vapor pressure (4~ 8´10-5 Pa), intensity (4~ 10 pA) and dwell time (5~ 128 ms) of ion-beam, designed pattern size, and nature of substrates. The flat and partially embedded Co dots were observed in the substrate surface layer (Figure 2). It is found that the size and shape of larger dots (diameters ~ 1mm) closely follow the designed patterns whereas the surface diffusion effect is found in those of smaller dots (diameters ~ 360 nm). Further studies involved fabrication of alloyed thin films/patterned dots are under investigation.
Research was supported by the Academic Frontier Center of the Japanese Ministry of Education, Culture, Sports, Science and Technology.
NSTI Nanotech 2003 Conference Technical Program Abstract