Effects of acetylene addition on mechanical and dielectric properties of amorphous carbon films

The para-xylene added with acetylene from 15% to 50% was plasma polymerized at 50 to 150 W to deposit the a-C:H films. After the films were annealed from 200 to 400 degrees C, the network structure, hardness and dielectric constant of films were analyzed by FT-IR, Raman, nanoindentor and capacitance-voltage plot, respectively. Those measured results suggest that hydrocarbon bonds and oxygen related bonds of the a-C:H film effectively reduce and the number of ordered aromatic rings increases with decreasing the deposition power after annealing at 400 degrees C. In addition, both the dielectric constant and the hardness, respectively, increase up to 2.82 and 2.37 GPa, but the adhesion strength decreases with increasing the C2H2 concentration and deposition power. Therefore, the a-C:H films not only have a lower dielectric constant, but also have enough mechanical strength for the IC processing. (c) 2005 Elsevier B.V. All rights reserved.