TaN薄膜的等离子体增强原子层沉积及其抗Cu扩散性能

Plasma-enhanced Atomic Layer Deposition of TaN Film and Its Resistance to Copper Diffusion

使用Ta[N(CH3)2]5和NH3等离子体作为反物用等离子体增强原子层沉积工艺生长了TaN薄膜,借助原子力显微镜、X射线光电子能谱、四探针和X射线反射等手段研究了薄膜的性能与工艺条件之间的关系。结果表明,TaN薄膜主要由Ta、N和少量的C、O组成。当衬底温度由250℃提高到325℃时Ta与N的原子比由46:41升高到55:35,C的原子分数由6%降低到2%。同时,薄膜的密度由10.9 g/cm3提高到11.6 g/cm3,电阻率由0.18Ω?cm降低到0.044Ω?cm。与未退火的薄膜相比,在400℃退火30 min后TaN薄膜的密度平均提高了～0.28 g/cm3,电阻率降低到0.12～0.029Ω?cm。在250℃生长的3 nm超薄TaN阻挡层在500℃退火30 min后仍保持良好的抗Cu扩散性能。

TaN films were deposited on monocrystalline silicon wafer via plasma enhanced atomic layer deposition with Ta[N(CH3)2]5as precursor and NH3 plasma as coreactant. The as deposited films were characterized by means of atomic force microscopy, X-ray photoelectron spectroscopy, four-point probe and X-ray reflection. The results show that the as-deposited film consists mainly of TaN with small quantities of C and O. As the deposition temperature increases from 250 oC to 325 oC, the ratio of Ta/N increases from 46:41 to 55:35, and the C-content(atomic fraction) decreases from 6% to 2%. Meanwhile,the resistivity of the film gradually decreases from 0.18 Ω?cm to 0.044 Ω?cm, and the film density increases from 10.9 g/cm3 to 11.6 g/cm3. After annealing at 400 oC for 30 min, the film density shows an increment of ~0.28 g/cm3 on average, and the film resistivity decreases to 0.12-0.029 Ω?cm. Further, the barrier performance test results indicate that the TaN film of 3 nm in thickness deposited at 250 oC demonstrates a perfect barrier function after annealing at 500 oC for 30 min.