# Study on hybrid au-underfill resin bonding method with lock-and-key structure for 3-D integration

Masatsugu Nimura, Jun Mizuno, Akitsu Shigetou, Katsuyuki Sakuma, Hiroshi Ogino, Tomoyuki Enomoto, Shuichi Shoji

Research output: Contribution to journalArticle

8 Citations (Scopus)

This paper describes a hybrid Au-underfill resin bonding method with lock-and-key structure for 3-D integration. In 3-D large scale integration (LSI), the gap between stacked chips becomes narrower because the bump dimension and pitch are smaller than those encountered in 2-D LSI. Therefore, the filling of gaps less than 10 $\mu{\rm m}$ using capillary forces often becomes insufficient because of the surface condition. To address this challenge, we study a hybrid bonding method in which the metal-metal and resin-resin bonding are carried out simultaneously with a chip resin applied previously only around the bump. To realize hybrid bonding on the entire chip, we fabricate indent and protrusion structures, which are called lock-and-key structures. The key structure is fabricated by a process that can remove the resin on the bumps by ${\rm O}2 plasma irradiation. The lock structure is fabricated by conventional photolithography and dry etching. By means of hybrid bonding with the lock-and-key structure, we have achieved the Au bump bonding and the filling of 4-$\mu{\rm m}$gaps between the stacked chips, concurrently. The cross-sectional transmission electron microscopy image of the bonded sample demonstrated that no significant gap exists at both the Au-Au and resin-resin interfaces. In addition, the shear strength of the sample bonded with resin is 10 times higher than that without the resin. The electrical continuity of the Au bump connections after hybrid bonding has also been determined. Original language English 6449300 558-565 8 IEEE Transactions on Components, Packaging and Manufacturing Technology 3 4 https://doi.org/10.1109/TCPMT.2013.2240566 Published - 2013 ### Fingerprint Resins LSI circuits Metals Dry etching Photolithography Shear strength Irradiation Transmission electron microscopy Plasmas ### Keywords • 3-D integration • Au bump • bonding • flip chip • micro-bump • underfill ### ASJC Scopus subject areas • Electrical and Electronic Engineering • Electronic, Optical and Magnetic Materials • Industrial and Manufacturing Engineering ### Cite this Study on hybrid au-underfill resin bonding method with lock-and-key structure for 3-D integration. / Nimura, Masatsugu; Mizuno, Jun; Shigetou, Akitsu; Sakuma, Katsuyuki; Ogino, Hiroshi; Enomoto, Tomoyuki; Shoji, Shuichi. In: IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 3, No. 4, 6449300, 2013, p. 558-565. Research output: Contribution to journalArticle Nimura, Masatsugu ; Mizuno, Jun ; Shigetou, Akitsu ; Sakuma, Katsuyuki ; Ogino, Hiroshi ; Enomoto, Tomoyuki ; Shoji, Shuichi. / Study on hybrid au-underfill resin bonding method with lock-and-key structure for 3-D integration. In: IEEE Transactions on Components, Packaging and Manufacturing Technology. 2013 ; Vol. 3, No. 4. pp. 558-565. @article{eedf25bd04a74defa9abaf5655e83b0b, title = "Study on hybrid au-underfill resin bonding method with lock-and-key structure for 3-D integration", abstract = "This paper describes a hybrid Au-underfill resin bonding method with lock-and-key structure for 3-D integration. In 3-D large scale integration (LSI), the gap between stacked chips becomes narrower because the bump dimension and pitch are smaller than those encountered in 2-D LSI. Therefore, the filling of gaps less than 10$\mu{\rm m}$using capillary forces often becomes insufficient because of the surface condition. To address this challenge, we study a hybrid bonding method in which the metal-metal and resin-resin bonding are carried out simultaneously with a chip resin applied previously only around the bump. To realize hybrid bonding on the entire chip, we fabricate indent and protrusion structures, which are called lock-and-key structures. The key structure is fabricated by a process that can remove the resin on the bumps by${\rm O}2 plasma irradiation. The lock structure is fabricated by conventional photolithography and dry etching. By means of hybrid bonding with the lock-and-key structure, we have achieved the Au bump bonding and the filling of 4-$\mu{\rm m}$ gaps between the stacked chips, concurrently. The cross-sectional transmission electron microscopy image of the bonded sample demonstrated that no significant gap exists at both the Au-Au and resin-resin interfaces. In addition, the shear strength of the sample bonded with resin is 10 times higher than that without the resin. The electrical continuity of the Au bump connections after hybrid bonding has also been determined.",
keywords = "3-D integration, Au bump, bonding, flip chip, micro-bump, underfill",
author = "Masatsugu Nimura and Jun Mizuno and Akitsu Shigetou and Katsuyuki Sakuma and Hiroshi Ogino and Tomoyuki Enomoto and Shuichi Shoji",
year = "2013",
doi = "10.1109/TCPMT.2013.2240566",
language = "English",
volume = "3",
pages = "558--565",
journal = "IEEE Transactions on Components, Packaging and Manufacturing Technology",
issn = "2156-3950",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "4",

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TY - JOUR

T1 - Study on hybrid au-underfill resin bonding method with lock-and-key structure for 3-D integration

AU - Nimura, Masatsugu

AU - Mizuno, Jun

AU - Shigetou, Akitsu

AU - Sakuma, Katsuyuki

AU - Ogino, Hiroshi

AU - Enomoto, Tomoyuki

AU - Shoji, Shuichi

PY - 2013

Y1 - 2013

N2 - This paper describes a hybrid Au-underfill resin bonding method with lock-and-key structure for 3-D integration. In 3-D large scale integration (LSI), the gap between stacked chips becomes narrower because the bump dimension and pitch are smaller than those encountered in 2-D LSI. Therefore, the filling of gaps less than 10 $\mu{\rm m}$ using capillary forces often becomes insufficient because of the surface condition. To address this challenge, we study a hybrid bonding method in which the metal-metal and resin-resin bonding are carried out simultaneously with a chip resin applied previously only around the bump. To realize hybrid bonding on the entire chip, we fabricate indent and protrusion structures, which are called lock-and-key structures. The key structure is fabricated by a process that can remove the resin on the bumps by ${\rm O}2 plasma irradiation. The lock structure is fabricated by conventional photolithography and dry etching. By means of hybrid bonding with the lock-and-key structure, we have achieved the Au bump bonding and the filling of 4-$\mu{\rm m}$gaps between the stacked chips, concurrently. The cross-sectional transmission electron microscopy image of the bonded sample demonstrated that no significant gap exists at both the Au-Au and resin-resin interfaces. In addition, the shear strength of the sample bonded with resin is 10 times higher than that without the resin. The electrical continuity of the Au bump connections after hybrid bonding has also been determined. AB - This paper describes a hybrid Au-underfill resin bonding method with lock-and-key structure for 3-D integration. In 3-D large scale integration (LSI), the gap between stacked chips becomes narrower because the bump dimension and pitch are smaller than those encountered in 2-D LSI. Therefore, the filling of gaps less than 10$\mu{\rm m}$using capillary forces often becomes insufficient because of the surface condition. To address this challenge, we study a hybrid bonding method in which the metal-metal and resin-resin bonding are carried out simultaneously with a chip resin applied previously only around the bump. To realize hybrid bonding on the entire chip, we fabricate indent and protrusion structures, which are called lock-and-key structures. The key structure is fabricated by a process that can remove the resin on the bumps by${\rm O}2 plasma irradiation. The lock structure is fabricated by conventional photolithography and dry etching. By means of hybrid bonding with the lock-and-key structure, we have achieved the Au bump bonding and the filling of 4-$\mu{\rm m}$ gaps between the stacked chips, concurrently. The cross-sectional transmission electron microscopy image of the bonded sample demonstrated that no significant gap exists at both the Au-Au and resin-resin interfaces. In addition, the shear strength of the sample bonded with resin is 10 times higher than that without the resin. The electrical continuity of the Au bump connections after hybrid bonding has also been determined.

KW - 3-D integration

KW - Au bump

KW - bonding

KW - flip chip

KW - micro-bump

KW - underfill

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