Thermal Atomic Layer Etching of Copper by Sequential Steps Involving Oxidation and Exposure to Hexafluoroacetylacetone
Thermal Atomic Layer Etching of Copper by Sequential Steps Involving Oxidation and Exposure to Hexafluoroacetylacetone
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DOI：
10.1149/2.0211809jss
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发表时间：
2018
影响因子：
2.2
通讯作者：
Elham Mohimi;Xiaoqing Chu;Brian B. Trinh;Shaista Babar;G. Girolami;J. Abelson
中科院分区：
文献类型：
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作者：
Elham Mohimi;Xiaoqing Chu;Brian B. Trinh;Shaista Babar;G. Girolami;J. Abelson
我们描述了一种铜的原子层蚀刻（ALE）方法，该方法涉及在275℃下循环暴露于氧化剂和六氟乙酰丙酮（Hhfac）。该工艺不会影响SiO2或SiNx等介质，并且表面反应在动力学上是自限制的，可以提供精确的蚀刻深度，并且在空间上是均匀的。将铜表面暴露于分子氧O2（一种弱氧化剂）中，形成约0.3 nm厚的Cu2O层，在随后的步骤中通过暴露于Hhfac去除Cu2O。蚀刻反应涉及Cu（hfac）中间体的歧化，因此每个周期去除~ 0.09 nm的铜。将铜暴露于臭氧（一种更强的氧化剂）中，可产生约15 nm的CuO；当这个氧化表面暴露在Hhfac中时，每个循环除去8.4 nm的铜。蚀刻产物Cu(hfac)2和H2O被有效地抽走；水是一种很差的氧化剂，不会腐蚀裸露的铜表面。在连续的蚀刻周期中，铜表面的粗糙度逐渐增加。热化学和大块蚀刻数据表明，这种方法应该适用于各种其他金属。©2018电化学学会。(DOI: 10.1149/2.0211809 js)
We describe an atomic layer etching (ALE) method for copper that involves cyclic exposure to an oxidant and hexafluoroacetylacetone (Hhfac) at 275◦C. The process does not attack dielectrics such as SiO2 or SiNx, and the surface reactions are kinetically self-limiting to afford a precise etch depth that is spatially uniform. Exposure of a copper surface to molecular oxygen, O2, a weak oxidant, forms a ∼0.3 nm thick layer of Cu2O, which is removed in a subsequent step by exposure to Hhfac. The etch reaction involves disproportionation of Cu(hfac) intermediates, such that ∼0.09 nm copper is removed per cycle. Exposure of copper to ozone, a stronger oxidant, affords ∼15 nm of CuO; when this oxidized surface is exposed to Hhfac, 8.4 nm of copper is removed per cycle. The etch products, Cu(hfac)2 and H2O, are efficiently pumped away; H2O, a poor oxidant, does not attack the bare Cu surface. The roughness of the copper surface increases slowly over successive etch cycles. Thermochemical and bulk etching data indicate that this approach should work for a variety of other metals. © 2018 The Electrochemical Society. [DOI: 10.1149/2.0211809jss]