Vertical and Lateral Copper Transport through Graphene Layers

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• 作者：Ling Li ; Xiangyu Chen ; Ching-Hua Wang ; Ji Cao ; Seunghyun Lee ; Alvin Tang ; Chiyui Ahn ; Susmit Singha Roy ; Michael S. Arnold ; H.-S. Philip Wong
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：9
• 期：8
• 页码：8361-8367
• 全文大小：441K
• ISSN：1936-086X

文摘

A different mechanism was found for Cu transport through multi-transferred single-layer graphene serving as diffusion barriers on the basis of time-dependent dielectric breakdown tests. Vertical and lateral transport of Cu dominates at different stress electric field regimes. The classic E-model was modified to project quantitatively the effectiveness of the graphene Cu diffusion barrier at low electric field based on high-field accelerated stress data. The results are compared to industry-standard Cu diffusion barrier material TaN. 3.5 脜 single-layer graphene shows the mean time-to-fail comparable to 4 nm TaN, while two-time and three-time transferred single-layer graphene stacks give 2脳 and 3脳 improvements, respectively, compared to single-layer graphene at a 0.5 MV/cm electric field. The influences of graphene grain boundaries on Cu vertical transport through the graphene layers are explored, revealing that large-grain (10鈥?5 渭m) single-layer graphene gives a 2 orders of magnitude longer lifetime than small-grain (2鈥? 渭m) graphene. As a result, it is more effective to further enhance graphene barrier reliability by improving single-layer graphene quality through increasing grain sizes or using single-crystalline graphene than just by increasing thickness through multi-transfer. These results may also be applied for graphene as barriers for other metals.