Browsing by Author "Juang, Jing-Ye"

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A new failure mechanism of electromigration by surface diffusion of Sn on Ni and Cu metallization in microbumps
(2018-04-12)
Chang, Yuan-Wei
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Hu, Chia-chia
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Peng, Hsin-Ying
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Liang, Yu-Chun
;
Chen, Chih
Microbumps in three-dimensional integrated circuit now becomes essential technology to reach higher packaging density. However, the small volume of microbumps dramatically changes the characteristics from the flip-chip (FC) solder joints. For a 20 mu m diameter microbump, the cross-section area and the volume are only 1/25 and 1/125 of a 100 mu m diameter FC joint. The small area significantly enlarges the current density although the current crowding effect was reduced at the same time. The small volume of solder can be fully transformed into the intermetallic compounds (IMCs) very easily, and the IMCs are usually stronger under electromigration (EM). These result in the thoroughly change of the EM failure mechanism in microbumps. In this study, microbumps with two different diameter and flip-chip joints were EM tested. A new failure mechanism was found obviously in microbumps, which is the surface diffusion of Sn. Under EM testing, Sn atoms tend to migrate along the surface to the circumference of Ni and Cu metallization to form Ni3Sn4 and Cu3Sn IMCs respectively. When the Sn diffuses away, necking or serious void formation occurs in the solder, which weakens the electrical and mechanical properties of the microbumps. Theoretic calculation indicates that this failure mode will become even significantly for the microbumps with smaller dimensions than the 18 mu m microbumps.
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
;
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.
Copper-to-Copper direct bonding on highly (111) oriented nano-twinned copper in no-vacuum ambient
(2017-01-01)
Juang, Jing-Ye
;
Lu, Chia-Ling
;
Chen, Kuan-Ju
;
Chang, Tao-Chih
;
Chen, Chih
In this study, we achieve the Cu-to-Cu direct bonding by using the (111) oriented nano-twined-Cu in N-2 ambient, without vacuum condition and no additional thermal annealing treatment is needed. A well bonded interface under a temperature gradient between 400 degrees C and 100 degrees C was identified by the evidence of the grown grain across the bonding interface. In addition, a creep assisted bonding mechanism for the Cu-Cu direct bonding is proposed. Moreover, a shear test was applied on the bonded joints for the investigation of the bonded joint strength and its fracture mode. The mean value of joint strength is 176 MPa which is significantly higher than the conventional solder joint. In summary, the Cu-to-Cu direct bonding by (111) oriented nt-Cu in no-vacuum ambient as well as the grain evolution across the bonding interface has been achieved and verified.
Copper-to-copper direct bonding on highly (111)-oriented nanotwinned copper in no-vacuum ambient
(2018-09-17)
Juang, Jing-Ye
;
Lu, Chia-Ling
;
Chen, Kuan-Ju
;
Chen, Chao-Chang A.
;
Hsu, Po-Ning
A vacuum-free Cu-to-Cu direct bonding by using (111)-oriented and nanotwinned Cu has been achieved. A fast bonding process occurs in 5 min under a temperature gradient between 450 and 100 degrees C. It is verified by grain growth across the bonded interface. To investigate the grain growth behavior, further annealing in the temperature gradient, as well as in a reversed temperature gradient, was performed. They showed similar recrystallization behavior with de-twinning. To analyze the de-twinning, we recall the classic model of annealing twin formation by Fullman and Fisher as comparison. Our case is opposite to the model of Fullman and Fisher. A mechanism of direct bonding by surface diffusion creep is proposed.
Correlation between the Microstructures of Bonding Interfaces and the Shear Strength of Cu-to-Cu Joints Using (111)-Oriented and Nanotwinned Cu
(2018-12-01)
Juang, Jing-Ye
;
Lu, Chia-Ling
;
Li, Yu-Jin
;
Tu, K. N.
;
Chen, Chih
Highly (111)-oriented Cu pillar-bumps were bonded to highly (111)-oriented Cu films at temperatures ranging from 200 degrees C/100 degrees C to 350 degrees C/100 degrees C in N-2 ambient conditions. The microstructures of the bonded interfaces affected the shear strength performance of the bonded Cu joints. The bonded interfaces at 300 degrees C/100 degrees C and 350 degrees C/100 degrees C had far fewer voids than interfaces bonded at 200 degrees C/100 degrees C and 250 degrees C/100 degrees C. In addition, grain growth took place across the bonding interfaces at temperatures above 300 degrees C/100 degrees C. The corresponding orientation map (OIM) showed the preferred orientation of large grown grains to be <100>. Shear tests revealed that the fracture mode was brittle for joints bonded at 200 degrees C/100 degrees C, but became ductile after bonded above 300 degrees C/100 degrees C. Based on the results, we found that voids and grain growth behavior play import roles in the shear strength performance of bonded Cu joints.
Effect of Joint Shape Controlled by Thermocompression Bonding on the Reliability Performance of 60 mu m-pitch Solder Micro Bump Interconnections
(2014-01-01)
Huang, Yu-Wei
;
Zhan, Chau-Jie
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Juang, Jing-Ye
;
Lin Yu-Min
;
Huang, Shin-Yi
Three dimensional integration circuits technology has received much attention recently since the demands of functionality and performance in microelectronic packaging for electronic products are rapidly increasing. For high-performance 3D chip stacking, high density interconnections are essential. In the current types of interconnects, solder micro bumps have been widely used and thermocompression bonding process are well adopted to form the connection between bumps. However, the prefect joint contour is difficult to obtain and control by such kind of bonding process in solder micro bump joints. For fine-pitch solder micro bump interconnections, the effect of joint shape on the reliability performances of the solder micro bump joints is not concluded yet till now and needs to be clarified. In this study, the effect of joint shape controlled by thermocompression bonding on the reliability performance of solder micro bump interconnections with a pitch of 60 mu m was discussed. The chip-to-chip test vehicle having more than 4000 solder micro bump interconnections with a bump pitch of 60 mu m was used in this study. A solder micro bump structure of Cu/SnAg having a thickness of 7 mu m/10 mu m was fabricated in both the silicon chip and substrate. To evaluate the effect of joint shape, four types of joint shape were controlled and made. The first type had a conventional shape of micro joint. Compared to the first one joint structure, the second type of joint structure showed the compressed shape. The third type of joint structure was the pillar-like micro joint while the fourth type of joint structure presented a neck shape having the highest joint height among all the joint structures tested. We used the fluxless thermocompression bonding process to form these four types of micro joints. After bonding process, the chip stack was assembled by capillary-type underfill. Reliability tests of temperature cycling test (TCT), high temperature storage (HTS) and electromigration test (EM) were selected to assess the effect of joint shape on the reliability properties of those four types of solder micro bump interconnections. The reliability results presented that all the types of joint structures could pass TCT of 1000 cycles and HTS of 1000 hours but high variation of daisy chain resistance more than 15% would happen in the neck-shape micro joint after TCT. For the neck-shape micro joint, the high variation of daisy chain resistance after TCT resulted from the cracking propagated along the interface of Cu UBM/Cu6Sn5 IMC and across the tin solder. The cracking situation was more serious as compared to the other three tested micro joints. The results of HTS revealed that resistance variation mainly depended on the micro structural evolution within micro joints tested. Electromigration test was conducted under the testing condition of 0.56 A/150 degrees C. A daisy chain structure was adopted. For both the pillar-shape and neck-shape micro joints, Cu UBM consumption and formation of large void were the major microstructure evolutions within the micro interconnections during EM testing. The conpressed-shape showed the longer electromigration lifetime among all the types of micro joints tested.
Fabrication of (111) nanotwinned Cu and its applications in interconnects of microelectronic devices
(2016)
Chen, Chih
;
Liu, Chien-Min
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Lu, Tien-Lin
;
Lin, Han-wen
;
Chu, Yi-Cheng
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 temperature Cu-Cu direct bonding by (111) oriented nano-twin Cu
(2017-01-01)
Juang, Jing-Ye
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Chu, Yi-Cheng
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Lu, Chia-Ling
;
Chen, Chih
;
Tu, King-Ning
In this study, a low temperature solid state diffusion bonding process with (111) highly oriented nano-twined Cu (nt-Cu) was proposed. A less void bonding interface was observed reveals a good bonding quality for the bonded samples. In addition, a large quasisingle grain was identified in the bonded film. Based on these results, it is believed that high strength and durable bonding structure can be accomplished by bonding two highly (111)-oriented nt-Cu films.
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.