{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T16:06:50Z","timestamp":1788970010705,"version":"build-2803163510"},"reference-count":32,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2022,11,4]],"date-time":"2022-11-04T00:00:00Z","timestamp":1667520000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006245","name":"Ministry of Science and Technology","doi-asserted-by":"publisher","award":["MOST 110-2622-E-002-016-CC1"],"award-info":[{"award-number":["MOST 110-2622-E-002-016-CC1"]}],"id":[{"id":"10.13039\/501100006245","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Cu-to-Cu direct bonding plays an important role in three-dimensional integrated circuits (3D IC). However, the bonding process always requires high temperature, high pressure, and a high degree of consistency in height. In this study, Sn is passivated over electroplated copper. Because Sn is a soft material and has a low melting point, a successful bond can be achieved under low temperature and low pressure (1 MPa) without any planarization process. In this experiment, Sn thickness, bonding temperature, and bonding pressure are variables. Three values of thicknesses of Sn, i.e., 1 \u03bcm, 800 nm, and 600 nm were used to calculate the minimum value of Sn thickness required to compensate for the height difference. Additionally, the bonding process was conducted at two temperatures, 220 \u00b0C and 250 \u00b0C, and their optimized parameters with required pressure were found. Moreover, the optimized parameters after the Cu planarization were also investigated, and it was observed that the bonding can succeed under severe conditions as well. Finally, transmission electron microscopy (TEM) was used to observe the adhesion property between different metals and intermetallic compounds (IMCs).<\/jats:p>","DOI":"10.3390\/ma15217783","type":"journal-article","created":{"date-parts":[[2022,11,4]],"date-time":"2022-11-04T09:19:33Z","timestamp":1667553573000},"page":"7783","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Investigation of Low-Pressure Sn-Passivated Cu-to-Cu Direct Bonding in 3D-Integration"],"prefix":"10.3390","volume":"15","author":[{"given":"Po-Yu","family":"Kung","sequence":"first","affiliation":[{"name":"Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei-Lun","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chin-Li","family":"Kao","sequence":"additional","affiliation":[{"name":"Product Characterization, Corporate R&D, Advanced Semiconductor Engineering (ASE) Group, Kaohsiung City 811, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yung-Sheng","family":"Lin","sequence":"additional","affiliation":[{"name":"Product Characterization, Corporate R&D, Advanced Semiconductor Engineering (ASE) Group, Kaohsiung City 811, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yun-Ching","family":"Hung","sequence":"additional","affiliation":[{"name":"Product Characterization, Corporate R&D, Advanced Semiconductor Engineering (ASE) Group, Kaohsiung City 811, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6685-0639","authenticated-orcid":false,"given":"C. R.","family":"Kao","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Das, S., Fan, A., Chen, K.-N., Tan, C.S., Checka, N., and Reif, R. (2004, January 18\u201321). Technology, performance, and computer-aided design of three-dimensional integrated circuits. Proceedings of the 2004 International Symposium on Physical Design, Phoenix, AZ, USA.","DOI":"10.1145\/981066.981091"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Liang, H.-W., Chen, H.-C., Lin, C.-H., Lee, C.-L., Yang, S.-C., and Chen, K.-N. (2016, January 8\u201311). The influence of device morphology on wafer-level bonding with polymer-coated layer. 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