Direct deposition of a blanket tungsten layer on SiO2 by preexposure of helium plasma

By utilizing preexposure of helium plasma, a method of depositing a blanket tungsten layer directly on SiO2 has been developed. When SiO2 films are ex posed to a helium plasma, oxygen atoms are knocked on by active species in the plasma and the surface becomes covered with reduced silicon. It is assu med that this silicon reacts with WF6 to form tungsten nuclei, and that tun gsten layers grow through the reaction of H-2 and WF6 at these nuclei. The deposited tungsten layer is stable with a low resistivity in the form of th e alpha-W crystal and shows strong adhesion to the SiO2 film due to the anc horing effect of tungsten. (C) 1999 American Institute of Physics. [S0021-8 979(99)03912-2].