Low Temperature Cu Interconnect with Chip to Wafer Hybrid Bonding

Gao, Guanghai; Mirkarimi, Laura; Workman, Thomas; Fountain, G. G.; Theil, Jeremy A.; Guevara, Gabe; Liu, Ping; Lee, Bongsub; Mrozek, P.; Huynh, Michael; Rudolph, Catharina; Werner, Thomas R.; Hanisch, Anke

doi:10.1109/ectc.2019.00100

Cited by 50 publications

(10 citation statements)

References 7 publications

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“…Depending on the sample type, hybrid bonding can be classified as die to wafer (D2W) and wafer to wafer (W2W) . Different from the W2W, D2W displays higher flexibility, higher yield rate and more application scenarios. , The process of D2W hybrid bonding contains wafer chemical mechanical polishing (CMP), die blading, plasma activation, prebonding and annealing .…”

Section: Introductionmentioning

confidence: 99%

The High-Adhesion Die-Cleaning Tape with Dual-Functional Groups for Die to Wafer (D2W) Hybrid Bonding

Zhang,

Lian,

Ding

et al. 2024

ACS Appl. Electron. Mater.

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With the rapid development of artificial intelligence, high performance computing will break through Moore's law and move toward three-dimensional (3D) package integration of chips. Hybrid bonding has become a potential solution for advanced packaging, as the interconnect pitch shrinks to less than 1 μm. Die to wafer (D2W) hybrid bonding consists of chemical mechanical polishing (CMP), blading, plasma activation, prebonding, and annealing processes. The diced dies that are attached to tape will undergo several steps such as cleaning and activation; therefore, the tape should present a high adhesion and stability property. This paper innovatively studies the adhesion and stability of tapes in a variety of chemicals and theoretically reveals the influence of the composition and structure of the tape adhesive layer on performance. Two types of tapes (A and B) from different brands have been tested and their average peeling strength on the dies was measured; the results present that tape A remains stable no matter in the acidic or alkaline solution, even with megasonics applied for a long time. The adhesive layer of tape A is closely connected to the substrate layer, and the surface roughness of 1.1 nm is much smaller than that of tape B. Besides, the XPS analysis verifies that there are abundant carboxyl and ester groups on the surface of the tape A adhesive layer, which contributes to the outstanding adhesion of dies on the tape and stability performance in a variety of chemical environments. This research reveals the reasons for the adhesion and stability performance of the tape, which will provide a theoretical basis for the selection of die cleaning tape and support the development of the D2W hybrid bonding process and high-density packaging technology.

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Section: Introductionmentioning

confidence: 99%

The High-Adhesion Die-Cleaning Tape with Dual-Functional Groups for Die to Wafer (D2W) Hybrid Bonding

Zhang,

Lian,

Ding

et al. 2024

ACS Appl. Electron. Mater.

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“…Low-temperature hybrid bonding or direct bond interconnecting is a popular industrial method by which to achieve the smallest possible bond pitches [ 18 , 19 , 20 ]. Surface cleaning and preparation via chemical-mechanical polishing is required to achieve sufficient planarity for atomic-scale dielectric bonding, followed by a post-annealing process [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Laser-Assisted Micro-Solder Bumping for Copper and Nickel–Gold Pad Finish

2022

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Flip-chip bonding is a key packaging technology to achieve the smallest form factor possible. Using copper as a direct under-bump metal and performing bonding under little force and at a low temperature eliminates the processing step for the deposition of a suitable wetting metal and offers an economical solution for electronic chip packaging. In this paper, various samples with copper and nickel–gold surface finishes are used to apply an in-house solder bumping, flip-chip bonding and reflow process to exhibit the bump-bond feasibility. Native oxides are reduced using process gases, and copper surface protection and solder wetting are achieved using copper formate. Lead-free 40 µm solder balls were bumped on 80 µm copper pads and 120 µm copper pillars to demonstrate a full intermetallic Cu–Cu bond as a base study for stacking applications. Using a low-force bonding technique, various chips with different dimensions were bonded at 0.5–16 MPa, followed by a reflow step at a maximum temperature of 270 ∘C. Then, 30 µm solder balls are utilized to bump the samples with NiAu and Cu bond pads at 50 µm pitch. A mean shear strength of 44 MPa was obtained for the 30 µm Cu samples. To the best of our knowledge, 30 µm solder bumping directly on the copper pads by producing copper formate is a novel research contribution.

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“…[19][20][21][22] In addition, due to the high power density and chip temperature in 3D stacking structure, the temperature influence on the performance of TSV is critical in its modeling, characterization, and design. [23][24][25] In order to further improving the transmission characteristics of TSV, a novel TSV structure, that is, elliptic cylindrical TSV, is proposed in this article. HFSS software is used to simulate the influence of structural parameters such as axial length ratio, height, dielectric layer thickness, and TSV spacing on the transmission characteristics of elliptic cylinder TSV model, and the relative optimal solution of each geometric parameter is obtained.…”

Section: Introductionmentioning

confidence: 99%

The design and optimization of novel elliptic cylindrical through‐silicon via and its temperature characterization

Guan

Zhang

et al. 2022

Engineering Reports

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Through‐silicon via (TSV) technology is a key technology to realize multi‐layer chips and its structure model and transmission characteristics have attracted much attention. With the continuous reduction of chip size, higher requirements are put forward for the model and transmission characteristics of TSV. A novel elliptic cylindrical TSV structure model is proposed. The influence of axial length ratio, height, dielectric layer thickness, and spacing on the transmission characteristics of TSV is further studied by HFSS software. The results show that the transmission of TSV is facilitated by the decrease of axial length ratio, the decrease of height, the increase of dielectric layer thickness, and the increase of TSV spacing. The TSV structural parameter values are optimized by a single variable method. The optimized TSV structure is compared with the original TSV, traditional cylindrical and conical TSV, and coaxial TSV. It is concluded that the elliptic cylindrical TSV structure has better transmission performance. The temperature characteristics of the elliptic cylindrical TSV are simulated. It is indicated that the transmission characteristics of the elliptic cylindrical TSV are poor at low frequency and better at high frequency when the temperature rises.

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Low Temperature Cu Interconnect with Chip to Wafer Hybrid Bonding

Cited by 50 publications

References 7 publications

The High-Adhesion Die-Cleaning Tape with Dual-Functional Groups for Die to Wafer (D2W) Hybrid Bonding

The High-Adhesion Die-Cleaning Tape with Dual-Functional Groups for Die to Wafer (D2W) Hybrid Bonding

Laser-Assisted Micro-Solder Bumping for Copper and Nickel–Gold Pad Finish

The design and optimization of novel elliptic cylindrical through‐silicon via and its temperature characterization

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