Cu互连中Ta-Si-N/Zr阻挡层热稳定性的研究

Thermal Stability of Ta-Si-N/Zr Barrier in Cu Metallization

摘要:

用射频反应磁控溅射的方法在Si(100)衬底和Cu膜间制备Ta-Si-N(10 nm)/Zr(20 nm)双层结构的扩散阻挡层。Cu/Ta-Si-N/Zr/Si样品在高纯氮气的保护下从600至800 ℃退火1 h。通过四探针电阻测试仪(FPP)、SEM、XRD和AES研究Cu/Ta-Si-N/Zr/Si系统在退火过程中的热稳定性。结果表明：沉积到Zr膜上的Ta-Si-N表面平坦，为典型的非晶态结构；Cu/Ta-Si-N/Zr/Si样品650 ℃以上退火后Zr原子扩散到Si中形成的ZrSi2能有效地降低Ta-Si-N与Si之间的接触电阻；Ta-Si-N/Zr阻挡层750 ℃退火后仍能有效地阻止Cu的扩散

Abstract:

Ta-Si-N(10 nm)/Zr(20 nm) bilayer diffusion barrier was prepared between n-type silicon(100) wafer and Cu film by radio frequency reactive magnetron sputtering. The Cu/Ta-Si-N/Zr/Si samples were subsequently annealed at different temperatures ranging from 600 to 800 oC in high-purity N2 gas for 1 h. The thermal stability of the Cu/Ta-Si-N/Zr/Si system during annealing was investigated by X-ray diffraction(XRD), auger electron spectroscopy(AES), scanning electron microscopy(SEM) and four-point probe technique(FPP). The results show that Ta-Si-N deposited on Zr film is amorphous with low roughness. In addition, the diffusion of Zr atoms into Si substrate results in ZrSi2 formation which decreases effectively the contact resistance between the barrier and Si after annealing of Cu/Ta-Si-N/Zr/Si sample above 650 oC. Ta-Si-N/Zr bilayer can serve as effective diffusion barrier up to 750 oC