Cu/SiO2表面选择性原子层沉积的前驱体分子计算筛选

Theoretical screening of precursors for selective atomic layer deposition on Cu/SiO2 surface

  • 摘要: 选择性原子层沉积技术在纳米级材料制造方面有着显著的优势,其本质是利用不同区域表面前驱体的不同反应速率差异实现选择性。本文针对半导体互联和后道工艺中介电材料对准沉积工艺,采用密度泛函理论结合微动力学方法,通过揭示前驱体吸附、分解机制,进一步耦合ALD反应工艺条件,实现对前驱体在Cu/SiO2表面反应速率和覆盖率的定量描述,以两种表面的覆盖率差异作为判据对十种Al/Si前驱体进行选择性筛选。结果表明,Cu表面吸附能范围−0.62 eV~−1.70 eV,SiO2表面吸附能范围−0.31 eV~−0.93 eV ,大部分前驱体在Cu表面反应能垒相较于SiO2表面的更低,DMAI在SiO2表面的反应能垒更低。DMAI在SiO2表面覆盖率与在Cu表面覆盖率之比分别为2.63×108,TEA和BEMAS在SiO2表面覆盖率接近于Cu表面,这三种前驱体具有SiO2选择性沉积的潜力,为实验前驱体的选择提供理论指导。

     

    Abstract: Selective atomic layer deposition(ALD) exhibits significant advantages in the fabrication of nanoscale materials, fundamentally leveraging the differential reaction rates of precursors across distinct regions. This study focuses on the deposition process alignment of dielectric materials in semiconductor interconnects and back-end processes. Using density functional theory (DFT) combined with micro-dynamics analysis, we elucidate the adsorption and decomposition mechanisms of the precursors. By further integrating these insights with ALD process conditions, we achieved a quantitative description of the reaction rates and coverages of precursors on Cu/SiO2 surfaces. The selectivity of ten Al/Si precursors was screened based on the coverage discrepancy between the two surfaces. Results indicate that the adsorption energies on Cu surfaces range from −0.62 eV to −1.70 eV, whereas on SiO2 surfaces, they range from −0.31 eV to −0.93 eV. For the majority of the precursors, the reaction energy barriers on Cu surfaces are lower than those on SiO2 surfaces. Notably, DMAI exhibits a lower reaction energy barrier on SiO2 surfaces. The coverage ratio of DMAI on SiO2 to Cu is 2.63×108, TEA and BEMAS demonstrate comparable coverage on both SiO2 and Cu surfaces, indicating their potential for selective deposition on SiO2. This study provides theoretical guidance for the experimental selection of precursors.

     

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