15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications

Thanh, Tung Bui; Kato, Fumiki; Watanabe, Naoya; Nemoto, Shunsuke; Kikuchi, Katsuya; Aoyagi, Masahiro

doi:10.7567/jjap.53.04eb04

Cited by 10 publications

(6 citation statements)

References 38 publications

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“…To overcome these limitations, existing literature has suggested self-alignment between the components and the interconnect layer. However, this may require a complicated fabrication process of three-dimensional structures [ 16 , 17 ]. Therefore, a simpler method of alignment is needed to perform efficient fabrication of functional electronic devices.…”

Section: Introductionmentioning

confidence: 99%

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

Ryu

Byun

Baek

et al. 2017

Sensors

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This study proposes a simple method of fabricating flexible electronic devices using a metal template for passive alignment between chip components and an interconnect layer, which enabled efficient alignment with high accuracy. An electrocardiogram (ECG) sensor was fabricated using 20 µm thick polyimide (PI) film as a flexible substrate to demonstrate the feasibility of the proposed method. The interconnect layer was fabricated by a two-step photolithography process and evaporation. After applying solder paste, the metal template was placed on top of the interconnect layer. The metal template had rectangular holes at the same position as the chip components on the interconnect layer. Rectangular hole sizes were designed to account for alignment tolerance of the chips. Passive alignment was performed by simply inserting the components in the holes of the template, which resulted in accurate alignment with positional tolerance of less than 10 µm based on the structural design, suggesting that our method can efficiently perform chip mounting with precision. Furthermore, a fabricated flexible ECG sensor was easily attachable to the curved skin surface and able to measure ECG signals from a human subject. These results suggest that the proposed method can be used to fabricate epidermal sensors, which are mounted on the skin to measure various physiological signals.

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Section: Introductionmentioning

confidence: 99%

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

Ryu

Byun

Baek

et al. 2017

Sensors

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“…In our previous works, we have succeeded in demonstrating of reliable Au microbump interconnections with submicron range bonding accuracy. The conventional bonding bump and pad elements have been appropriately modified to construct a concave-convex pair, i.e., self-aligned intercon- nection elements (SIEs), [15][16][17][18][19][20][21] for having highly reproducible submicron range bonding precision in the x-and y-axes. Moreover, with this bonding approach, bonding height could be determined during the bonding period through the applied bonding forces [Fig.…”

Section: Introductionmentioning

confidence: 99%

A method enabling height-control of chips for edge-emitting laser stacking

Thanh¹,

Ma²,

Amano³

et al. 2015

Jpn. J. Appl. Phys.

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In this paper we present a stacking method that enables the mounting of edge-emitting laser (EEL) devices at compulsory positions for feeding a coupling waveguide at a low temperature, i.e., 110 °C. Bonding laser chips are integrated to an interposer with embedded waveguides using an electrically conductive adhesive (ECA), i.e., silver-filled epoxy resin that relied on the surface tension phenomenon. A simple dispensing technique based on the capillary effect was used to generate adhesive droplets for bonding purposes. The ability to control the bonding height from 3 to 25 µm was demonstrated. While the post-bond in-plane offsets of the bonding EEL chip are determined by the accuracy of the bonder (i.e., within 2 µm range), the bonding height can be engineered, with a deviation within 1 µm, by balancing the external bonding forces with the surface tension of a certain adhesive volume. The reliability of the bond, i.e., bond strength of 106 gf, and heat dissipation function of the ECA, were also validated. The results obtained in this work imply that the use of this low-temperature, height-controllable approach for the stacking of EEL continues to look highly promising.

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“…Among 3D interconnects, thousands of 10-μm diameter Cu TSV and fine pitch Cu pillar (Sn bump) pairs in a 100-μm depth Si interposer are demonstrated to improve a wider bandwidth multi-function and large pin-out chip [4], [5]. However, current Cu pillars pitch larger than 20-μm cannot satisfy increasing CMOS device density [6], [7]. Although highly dense pairs of TSV and bump are required to realize vertical interconnection, there is still no clear solution to achieve the bump miniaturization.…”

Section: Introductionmentioning

confidence: 99%

Submicron Cu/Sn Bonding Technology With Transient Ni Diffusion Buffer Layer for 3DIC Application

Chang

Hsieh

Chen

2014

IEEE Electron Device Lett.

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A submicron Cu/Sn bonding with transient Ni buffer layer at 225°C is demonstrated to overcome current 5-µm Cu/Sn physical limitation. The 10-nm Ni layer suppresses immense Cu/Sn interdiffusion during heating step prior to major bonding process. When the temperature is close to the Sn melting point, the Ni layer dissolves and molten Sn gives successful submicrometer Cu/Sn bonding. The excellent mechanical strength and electrical performance of this scheme show the great potential for future and highly dense 3D interconnects.

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15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications

Cited by 10 publications

References 38 publications

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

A method enabling height-control of chips for edge-emitting laser stacking

Submicron Cu/Sn Bonding Technology With Transient Ni Diffusion Buffer Layer for 3DIC Application

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