不同氮气流量AlCrTaTiZr高熵合金氮化物薄膜扩散阻挡性能研究

Diffusion Barrier Properties of AlCrTaTiZr High-entropy Alloy Nitride Films with Different Nitrogen Flow Rates

目的提高铜互连扩散阻挡层的失效温度。方法采用磁控溅射方法制备了不同氮气流量下的Cu/AlCrTaTiZrNx/Si高熵合金薄膜体系,使用真空退火炉对Cu/AlCrTaTiZrNx/Si高熵合金薄膜体系分别进行600、700、800、900℃的真空退火,并利用扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)以及透射电子显微镜(TEM)等表征手段对薄膜的组织结构、三维形貌等进行表征。结果不通入氮气时,高熵合金薄膜为非晶状态。随着氮气流量的增加,薄膜的结晶性越来越好,薄膜为FCC结构。随着氮气流量的增加,高熵合金薄膜表面粗糙度呈现下降的趋势,在氮气流量为20%时,高熵合金氮化物薄膜的致密性最好。Cu/AlCrTaTiZrN20/Si薄膜体系的扩散阻挡层结构主要为非晶包裹的纳米晶结构。薄膜在800℃退火后,没有Cu-Si化合物存在,薄膜方阻为0.0937Ω/□;在900℃退火后,Cu/AlCrTaTiZrN20/Si薄膜体系中Si基体部分出现不规则五边形状的大颗晶粒Cu-Si化合物。结论AlCrTaTiZrNx高熵合金氮化物薄膜的扩散阻挡性能随着氮气流量的增加,呈现先增加后降低的趋势。在氮气流量为20%时,高熵合金氮化物薄膜的扩散阻挡性能最优,800℃高温退火后仍发挥阻挡作用。

The work aims to improve the failure temperature of the copper interconnect diffusion barrier.Cu/AlCrTaTiZrNx/Si high-entropy alloy thin film system was deposited by reactive magnetron sputtering under different nitrogen flow rates and then vacuum-annealed at 600,700,800,900℃.The microstructure,3D morphology,etc.of the thin film were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM),X-ray diffraction(XRD)and transmission electron microscopy(TEM).The high-entropy alloy film was amorphous in the condition without nitrogen.As the flow rate of nitrogen increased,the crystallinity of the film became better and the film structure was FCC structure.With the increase of nitrogen flow rate,the surface roughness of this film decreased.The high-entropy alloy nitride film had the best compactness at a nitrogen flow rate of 20%.The diffusion barrier structure of the Cu/AlCrTaTiZrN20/Si thin film system was mainly amorphous-coated nanocrystalline structure.After annealing at 800℃,there was no Cu-Si compound in the thin film and the sheet resistance was 0.0937Ω/□.After annealing at 900℃,a large number of large-grained high-resistivity Cu-Si compounds in irregular pentagon emerged at Si substrate of Cu/AlCrTaTiZrNx/Si high-entropy alloy thin film system.As the nitrogen flow rates increases,the diffusion barrier property of the AlCrTaTiZrNx high-entropy alloy nitride film first increases and then decreases.The diffusion barrier property of the high-entropy alloy nitride film is optimal at a nitrogen flow rate of 20%,and can still act as a barrier after annealing at 800℃.