| abstract |
Since solid solution metals having abrasion resistance are hard to be scratched, eroded or damaged during chemical-mechanical polishing, coating low-resistance metal conductors or vias with solid solution metals can effectively use chemical-mechanical polishing techniques. After physical vapor deposition (eg evaporation or collimation sputtering) of low resistive metals or alloys, the chemical vapor deposition and solidification of the solid solution metals can produce high quality conductors and vias. By varying the ratio of SiH 4 to WF 6 during coating of the solid solution metal by chemical bonding, the amount of silicon incorporated into the tungsten coating layer can be controlled. Collimation sputtering allows the formation of a solid-solder metal liner in the openings in the dielectric that serves as a suitable diffusion barrier for CVD tungsten as well as copper-based metal films. Ideally, for metals that are rapidly diffusing, such as copper, the liner is provided by a two-stage collimation sputtering process, at a relatively low vacuum (e.g., Im Torr or less) where directional deposition becomes significant. The first layer is formed, and the second layer is formed at a relatively high vacuum pressure (e.g., Im Torr or higher) where scattering deposition becomes significant. For solid solution metals such as CVD tungsten, the liner is formed by a one step process of collimating sputtering at high vacuum pressure. |