Tantalum metallization using an electron-cyclotron-resonance plasma source coupled with divided microwaves

Tantalum film deposition using an electron-cyclotron-resonance (ECR) plasma source coupled with divided microwaves has been investigated. In this technique, we can obtain high quality thin films because of the enhancement of the sputtering and film formation reaction achieved by highly ionized ECR plasma. Beta tantalum with high compressive stress and high resistivity (150 mu Omega cm) was obtained by Ar plasma. By using Xe, however, alpha-Ta with a resistivity of 13 to 18 mu Omega cm was obtained, at temperatures as low as 150 degrees C, by the moderate ion-bombardment effect of Xe. The compressive internal stress decreased with increasing temperature or film thickness. The stress change in air was less than 5 MPa for 0.6-mu m-thick film even after 10(3) h exposure in air. Fine patterns with 0.12 mu m width were etched into 0.4-mu m-thick Ta by ECR etching. We can obtain low stress, low resistivity, and stable Ta films using ECR sputter deposition by controlling the ion bombardment effect. We demonstrated that ECR sputter deposition can be used for deposition of Ta film as absorbers of x-ray masks and as diffusion barriers in large scale integrated devices. (C) 1997 American Vacuum Society.