Ruthenium (Ru) is an alternative to copper (Cu) and cobalt (Co) interconnect layers in sub 20 nm features due to its low resistivity in scaled wires and low diffusion into porous low-K dielectrics (SiCOH). Two goals for a successful Ru atomic layer deposition (ALD) process are to enable films with resistivity values as close as possible to that of bulk Ru and to enable selective deposition to achieve bottom-up fill of vias. In this work, the effects of dose variation on resistivity and selectivity of the Ru ALD process using a dicarbonyl-bis(5-methyl-2, 4-hexanediketonato) Ru(II) precursor, Ru(IHD)₂(CO)₂ (“Carish”), and O₂/He coreactant were investigated. Instead of varying the Carish precursor dose to optimize the growth rate per cycle, the precursor dose was optimized to reduce the film resistivity from 18.5 to 10.2 μΩ cm. By varying the O₂/He coreactant dose, the substrate selectivity of the ALD process was successfully enhanced as evidenced by the increased nucleation delay on bis(N,N-dimethylamino)dimethylsilane passivated SiO₂ over hydrofluoric acid-cleaned SiO₂. These findings highlight the importance of dose optimization beyond the ALD saturation point in developing a selective and low resistivity Ru ALD process. Density functional theory calculations were performed to provide a mechanistic understanding of the underlying surface reactions of the Carish precursor and the roles of CH₃ passivation and O₂ coreactants.

中文翻译：

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剂量优化在低电阻率薄膜 Ru 原子层沉积中的作用

钌 (Ru) 是亚 20 nm 特征中铜 (Cu) 和钴 (Co) 互连层的替代品，因为它在缩放导线中的电阻率低，并且扩散到多孔低 K 电介质 (SiCOH) 中的程度低。成功的 Ru 原子层沉积 (ALD) 工艺的两个目标是使薄膜的电阻率值尽可能接近体 Ru 的电阻率值，并实现选择性沉积以实现自下而上的通孔填充。在这项工作中，使用二羰基-双（5-甲基-2, 4-己二酮）Ru(II) 前体 Ru(IHD) ₂ (CO) ₂ ( “Carish”）和 O ₂/He 共反应物进行了研究。不是改变 Carish 前体剂量来优化每个循环的生长速率，而是优化前体剂量以将薄膜电阻率从 18.5 降低到 10.2  μ Ω cm。通过改变 O _{2 /He 共反应剂剂量，ALD 工艺的基板选择性成功提高，双（N，N-二甲基氨基）二甲基硅烷钝化 SiO 2}比氢氟酸清洗的 SiO ₂的成核延迟增加证明了这一点. 这些发现强调了超出 ALD 饱和点的剂量优化在开发选择性和低电阻率 Ru ALD 工艺中的重要性。执行密度泛函理论计算以提供对 Carish 前体的潜在表面反应以及 CH ₃钝化和 O ₂共反应物的作用的机制理解。