Patent ID: 7166532

Claim:
A method for forming a contact using a Cu line in semiconductor fabrication, comprising: forming a dual damascene pattern by etching a pre-metal dielectric (PMD) layer formed on a substrate, wherein the dual damascene pattern includes a contact hole portion located on the substrate and a trench portion located on the contact hole portion, the width of the contact hole portion being narrower than that of the trench portion; depositing a tungsten diffusion barrier on sidewalls of the damascene pattern; completely filling the damascene pattern with tungsten by depositing tungsten on the tungsten diffusion barrier to form a tungsten layer; chemical mechanical polishing a portion of the tungsten layer over the trench portion; etching an upper part of the tungsten layer in the trench portion so as to not expose a void in the contact hole portion, thereby forming a tungsten plug that occupies a lower part of the tungsten layer in the trench portion and the contact hole portion; depositing a Cu diffusion barrier on the tungsten plug; depositing a Cu on the Cu diffusion barrier; and removing a portion of the Cu outside of the trench portion by a Cu chemical mechanical polishing process.