{"title":"Nanocrystalline copper for direct copper-to-copper bonding with improved cross-interface formation at low thermal budget.","authors":"Chuan He, Jingzhuo Zhou, Rui Zhou, Cong Chen, Siyi Jing, Kaiyu Mu, Yu-Ting Huang, Chih-Chun Chung, Sheng-Jye Cherng, Yang Lu, King-Ning Tu, Shien-Ping Feng","doi":"10.1038/s41467-024-51510-7","DOIUrl":null,"url":null,"abstract":"<p><p>Direct copper-to-copper (Cu-Cu) bonding is a promising technology for advanced electronic packaging. Nanocrystalline (NC) Cu receives increasing attention due to its unique ability to promote grain growth across the bonding interface. However, achieving sufficient grain growth still requires a high thermal budget. This study explores how reducing grain size and controlling impurity concentration in NC Cu leads to substantial grain growth at low temperatures. The fabricated NC Cu has a uniform nanograin size of around 50 nm and a low impurity level of 300 ppm. To prevent ungrown NC and void formation caused by impurity aggregation, we propose a double-layer (DL) structure comprising a normal coarse-grained (CG) layer underneath the NC layer. The CG layer, with a grain size of 1 μm and an impurity level of 3 ppm, acts as a sink, facilitating impurity diffusion from the NC layer to the CG layer. Thanks to sufficient grain growth throughout the entire NC layer, cross-interface Cu-Cu bonding becomes possible under a low thermal budget, either at 100 °C for 60 min or at 200 °C for only 5 min.</p>","PeriodicalId":19066,"journal":{"name":"Nature Communications","volume":null,"pages":null},"PeriodicalIF":14.7000,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11330484/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nature Communications","FirstCategoryId":"103","ListUrlMain":"https://doi.org/10.1038/s41467-024-51510-7","RegionNum":1,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MULTIDISCIPLINARY SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Direct copper-to-copper (Cu-Cu) bonding is a promising technology for advanced electronic packaging. Nanocrystalline (NC) Cu receives increasing attention due to its unique ability to promote grain growth across the bonding interface. However, achieving sufficient grain growth still requires a high thermal budget. This study explores how reducing grain size and controlling impurity concentration in NC Cu leads to substantial grain growth at low temperatures. The fabricated NC Cu has a uniform nanograin size of around 50 nm and a low impurity level of 300 ppm. To prevent ungrown NC and void formation caused by impurity aggregation, we propose a double-layer (DL) structure comprising a normal coarse-grained (CG) layer underneath the NC layer. The CG layer, with a grain size of 1 μm and an impurity level of 3 ppm, acts as a sink, facilitating impurity diffusion from the NC layer to the CG layer. Thanks to sufficient grain growth throughout the entire NC layer, cross-interface Cu-Cu bonding becomes possible under a low thermal budget, either at 100 °C for 60 min or at 200 °C for only 5 min.
期刊介绍:
Nature Communications, an open-access journal, publishes high-quality research spanning all areas of the natural sciences. Papers featured in the journal showcase significant advances relevant to specialists in each respective field. With a 2-year impact factor of 16.6 (2022) and a median time of 8 days from submission to the first editorial decision, Nature Communications is committed to rapid dissemination of research findings. As a multidisciplinary journal, it welcomes contributions from biological, health, physical, chemical, Earth, social, mathematical, applied, and engineering sciences, aiming to highlight important breakthroughs within each domain.