The structure and annealing properties of multilayer carbon films

Abstract

We investigate the structure and annealing properties of multilayer carbon films consisting of alternating layers of high density and low density amorphous carbon produced using two methods. The first method uses plasma immersion ion implantation (PIII) to create alternating high density (PIII off) and low density (PIII on) films. The second involves the formation of high and low density layers by changing the level of DC bias. Both methods allow thick films to be deposited without excessive stress build up. We use cross-sectional transmission electron microscopy (X-TEM), diffraction and electron energy loss spectroscopy (EELS) to investigate the microstructure of the films both before and after annealing to temperatures of 600 °C. High DC biases were found to cause modification of the surface of any subsequently deposited film (either low or high density). This modification can be attributed to ion implantation effects, which occur when using high DC biases. We found that the structure of high density layers in the multilayers was not greatly affected by annealing, however, low density layers develop strong preferred orientation either as a result of elevated deposition temperatures or post deposition annealing.