Precise Control of Nanoscale Cu Etching via Gas-Phase Oxidation and Chemical Complexation
Precise Control of Nanoscale Cu Etching via Gas-Phase Oxidation and Chemical Complexation
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通过气相氧化和化学络合精确控制纳米级铜蚀刻
DOI：
10.1021/acs.jpcc.0c08932
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Chang, Jane P.
中科院分区：
文献类型：
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作者：
Sheil, Ryan;Martirez, J. Mark;Sang, Xia;Carter, Emily A.;Chang, Jane P.
我们提出了一个循环的过程中选择性和各向异性的原子层蚀刻铜：氧等离子体调制的深度和方向性的氧化层，而甲酸蒸汽选择性地去除氧化铜规模从金属铜。通过密度泛函理论，与有限的温度和压力自由能修正，我们评估的可行性形成的气相Cu（II）和Cu（I）配合物与甲酸，水，甲酸，及其组合作为配体。这些络合物是由氧化铜（CuO和Cu 2 O）和甲酸之间的中和反应产生的，有水和没有水。我们确定并评估了甲酸，甲酸，aquahoxo，和aquaforato配合物的Cu（II）和Cu（I）的形成自由能。在相关的实验压力下，我们发现无水的二聚四（μ-formato）二铜（II）“桨轮”配合物（Cu 2（HCOO）4）是最有利的蚀刻产物，其形成从CuO达到平衡条件。二聚体最可能的前体是二甲酸铜（II）单体，其在二聚体持续存在的相同贫水条件下有利地二聚。因此，可以通过络合来实现气相Cu（氧化物）衍生物的稳定化，从而能够进行Cu的气相蚀刻。这项工作提供了补充的实验和理论研究，阐明了高度控制的性质与甲酸的纳米级氧化铜（S）层覆盖铜纳米结构，这是相关的下一代集成电路的制造。
We present a cyclic process for selective and anisotropic atomic layer etching of copper: an oxygen plasma modulates the depth and directionality of the oxidized layer, while formic acid vapor selectively removes the copper oxide scale from the metallic copper. Via density functional theory, with finite temperature and pressure free energy corrections, we evaluate the feasibility of formation of gas-phase Cu(II) and Cu(I) complexes with formate, water, formic acid, and combinations thereof as ligands. These complexes result from the neutralization reaction between copper oxide (CuO and Cu2O) and formic acid, with and without water. We identified and evaluated the formation free energies of formato, formic acid, aquahydroxo, and aquaformato complexes of Cu(II) and Cu(I). Under relevant experimental pressures, we find the water-free dimeric tetra(μ-formato)dicopper(II) “paddlewheel” complex (Cu2(HCOO)4) to be the most favorable etching product, with its formation reaching equilibrium conditions from CuO. The most likely precursor for the dimer is the diformatodi(formic acid)copper(II) monomer, which favorably dimerizes under the same water-lean condition at which the dimer persists. Stabilization of gas-phase Cu (oxide) derivatives thus can be achieved through complexation, enabling gas-phase etching of Cu. This work provides complementary experimental and theoretical studies that illuminate the nature of highly controlled etching with formic acid of nanoscopic CuO(s) layers covering Cu nanoarchitectures, which is relevant for the fabrication of next-generation integrated circuits.