Improvement of multilayer graphene quality by current stress during thermal CVD

To improve crystallinity and surface morphology of multilayer graphene (MLG) films for interconnect applications, a new CVD method which introduces current stress during thermal CVD have been investigated using cobalt (Co) as the catalyst. MLG crystallinity, which is indicated by intensity ratio of G and D peaks in Raman spectra (I_G/I_D ratio), increased as the current was increased, and the maximum I_G/I_D ratios of 44 and 30 were obtained at the furnace temperature of 500 and 400 °C, respectively. Comparing with thermal CVD without direct current at the same sample temperature after taking the rising sample temperature into account due to Joule heating, higher I_G/I_D ratio was still led by the current enhanced CVD (CECVD) with lesser agglomeration. Besides Joule heating that may have influence in enhancing MLG growth, we assume other effects of direct current may have additional influence through grain growth of Co catalytic layer. We believe additional current in thermal CVD will lead to better control of MLG growth for interconnect applications.