Browsing by Author "Shie, Kai Cheng"

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Chip-to-chip copper direct bonding in no-vacuum ambient using (111) oriented nano-twinned copper
(2018-01-01)
Juang, Jing Ye
;
Shie, Kai Cheng
;
Li, Yu Jin
;
Lin, Benson
;
Chang, Chia Cheng
In this study, we demonstrate the chip-to-chip copper direct bonding by using (111) oriented nano-twinned copper in N-2 ambient, without vacuum. A well bonded interface in the Cu-to-Cu joint was identified by the focus ion beam (FIB) microstructure observation. The secondary electron images (SEI) showed a void-less bonding interface within the bonded Cu joint. In addition, a die shear test was conducted. The test result revealed that the Cu joint has a robust bonded Cu structure due to its high value. The shear strength is more than 100 MPa. There is nearly twice strength value higher than the traditional SnAg solder joint (64 MPa). In addition, the scanning electron microscope (SEM) image showed the joint fractured in a ductile manner. Besides, we also performed the resistance measurement by using Kelvin probes on the bonded chip-to-chip test vehicle. The result showed 4.12 m Omega in single joint resistance and 4.26 x 10(-8) Omega.cm(2) in contact resistivity. More than 30% resistance reduction has been confirmed as compared to the traditional SnAg solder joint (6.32 m Omega). Moreover, for further post annealing process on the bonded test vehicle, we can further reduce the joint resistance by the value of 2.9 m Omega. It approaches the value of bulk Cu. The evidences revealed that the Cu-to-Cu joint is superior to the traditional SnAg solder. In last, the chip-to-chip copper direct bonding by using (111) oriented nano-twinned copper in N-2 ambient was achieved.
Copper direct bonding with short time and excellent electrical property by < 111 >-oriented nano-twinned copper
(2019-01-01)
Shie, Kai Cheng
;
Juang, Jing-Ye
;
Chen, Chih
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材料科學與工程學系
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Department of Materials Science and Engineering
In order to be compatible with semiconductor manufacturing, nanotwinned Cu microbumps were fabricated on 8 '' wafers. The pair of top and bottom dies were jointed through thermal compression bonding. After 1 min bonding time, the resistance could obtaine from all test structures, which indicates all the microbumps were bonded in the short time successfully.
Instant Cu-to-Cu direct bonding enabled by < 111 >-oriented nanotwinned Cu bumps
(2020-02-01)
Shie, Kai Cheng
;
Juang, Jing-Ye
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Cu-to-Cu direct bonding was successfully achieved in 10 s with < 111 >-oriented nanotwinned Cu (nt-Cu) bumps in ambient N-2. The bonding temperature and pressure were 300 degrees C and 90 MPa, respectively. A nearly void-free interface and a low bump resistance of 4.9 m Omega can be observed after a short-time bonding process. Besides, longer bonding times of 60 s and 30 s were employed, but the resistances of the Cu joints did not decrease significantly when the bonding time increased to 60 s. However, the nt-Cu columnar grains started to recrystallize during the 60 s bonding and started detwinning in 10 s bonding. Yet, the bonding interface remained under such a short bonding time. (C) 2019 The Japan Society of Applied Physics
Low resistance and high reliable Cu-to-Cu joints using highly (111)-oriented nano-twinned copper
(2019-01-01)
Juang, Jing Ye
;
Shie, Kai Cheng
;
Li, Yu Jin
;
Tu, K. N.
;
Chen, Chih
In this study, we present a chip-to-chip copper direct bonding technique in N-2 ambient, without vacuum by using (111) oriented nano-twinned copper. A well bonded copper joint was identified by the cross-sectioning process and microstructure observation. The cross-sectional images showed a void-less bonding interface in the bonded copper joint. In addition, we conducted resistance measurement using Kelvin probes on the bonded chip-to-chip test vehicle. The resistance for a daisy chain loop (400 joints) and the Kelvin structure (single joint) are 5.28 Omega and 4.14 m Omega, respectively. The contact resistivity is 3.98 x 10(-8) Omega.cm(2). More than 30% resistance reduction in the single Cu joint has been confirmed as compared to the SnAg solder joint (6.32 m Omega). Besides, temperature cycling test shows that the daisy chain loop with 400 Cu joints can stand the 1,000 cycles without failure. In summary, the chip-to-chip copper direct bonding in no-vacuum ambient has been successfully achieved by using (111) oriented nt-Cu. The low resistance as well as a reliable Cu-to-Cu joint can be achieved.
Low-resistance and high-strength copper direct bonding in no-vacuum ambient using highly (111)-oriented nano-twinned copper
(2019-01-01)
Juang, Jing Ye
;
Shie, Kai Cheng
;
Hsu, Po-Ning
;
Li, Yu Jin
;
Tu, K. N.
In this study, we fabricated (111)-oriented nt-Cu microbumps with 30 mu m in diameter, and bonded them together using chip-to-chip scheme in N-2 ambient, without vacuum. A well bonded interface in the Cu-to-Cu joint was identified by focused ion beam (FIB). Scanning electron microscope (SEM) images showed a void-less bonding interface within the bonded Cu joint. In addition, a die shear test was conducted. The test results revealed that the Cu joint has a robust bonded Cu joint and the shear strength is 124 MPa, which is nearly two times higher than the traditional SnAg solder joint (64 MPa). In addition, fracture analysis showed that the joint fractured in a ductile manner. Besides, we also performed the resistance measurement by using Kelvin probes on the bonded chip-to-chip test vehicles. The resistance is 4.12 m Omega for a single joint resistance and 4.26 x 10(-8) Omega.cm(2) in contact resistivity. More than 30% resistance reduction has been confirmed as compared to the traditional SnAg solder joint (6.32 m Omega). Moreover, we can further reduce the joint resistance by the post-annealing process. It can be brought down to 3.27 m Omega with a resistivity of 3.14 x 10(-8) Omega.cm(2). There is a nearly 50% resistance reduction, as compared to SnAg solder joint. The resistance value after the second annealed Cu joint is close an ideal Cu joint. In summary, low-resistance and high-strength copper direct bonding in no-vacuum ambient using highly (111)-oriented nano-twinned copper has been successfully achieved.
Low-temperature Cu-to-Cu direct bonding enabled by highly (111)-oriented and nanotwinned Cu
(2019-01-01)
Chen, Chih
;
Juang, Jing-Ye
;
Chang, Shih Yang
;
Shie, Kai Cheng
;
Li, Yu Jin
In this study, a low temperature diffusion bonding enabled by (111) highly oriented nanotwinned Cu (nt-Cu) was proposed. Two different bonding atmospheres, one is in IOW vacuum bonding, and another is in N-2 bonding were carried out. Both of the two bonding atmospheres show good bonding interfaces after microstructure observation. For vacuum ambient, large-grained structure was found after 250 degrees C for 90 min at 1 MPa in vacuum bonding. The size was as large as 40 mu m in width and 10 mu m in height. For non-vacuum conditions, the nt-Cu bumps can be bonded to nt-Cu films at the 250 degrees C for 20 min under 40.6 MPa. Accordingly, it is believed that low temperature bonding in low vacuum or non-vacuum ambients can be accomplished by using highly (111)-oriented nt-Cu.