Composite diffusion barrier for protecting copper interconnects in low dielectric constant materials from oxidation

摘要

A composite diffusion barrier (26,28) protects copper structure (30) from oxidation in the presence of oxygen or water in an integrated circuit. The copper structure (30) may be a dual damascene conductor with conductor (32) and via portions (34). The composite barrier includes dense diffusion barrier (28), which may be made of tantalum and/or tantalum nitride, and barrier film (26) capable of forming a protective oxide in a self limiting manner in the presence of oxygen or water. Oxidation of barrier film (26) enables in-situ repair of defects such as pinholes in the diffusion barrier (28). The barrier film (26) may contain aluminium, silicon or Cu3Ge. The composite barrier (26,28) is situated in a semiconductor device, which includes an insulator layer (20), which may have low dielectric constant k and high permeability. The device may also have nitride cap (38).