Void-Free Copper Pillar Hybrid Wafer Bonding Using a BCB Based Polymer Adhesive and Chemical Mechanical Polishing

Gallagher, Michael; Kozhukh, Julia; VanHanehem, Matthew; Anzures, Ed; Bell, Rosemary; Kondo, Masaki

doi:10.1109/ectc.2018.00225

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…Therefore, to obtain a high‐quality Cu/polymer interface, the following multiple processing steps are required: 1) polymer's CMP covered on Cu, 2) aggressive CMP to lower the height of Cu, and 3) fine CMP to secure the roughness of Cu. [ 32 ]…”

Section: Challenges Of Cu/polymer Hybrid Bondingmentioning

confidence: 99%

“…Fully cured polymer hybrid bonding is being actively studied through Benzocyclobutene (BCB), Polyimide (PI), SU-8, and Cyclic-olefin polymers (COP), as summarized in Table 1. [32][33][34][35][36][37][38] These materials have high heat resistance; so, they can be applied even at high bonding temperatures. In addition, they have little flowability and excellent physical properties; so, they can withstand processes such as CMP.…”

Section: Process Of Cu/polymer Hybrid Bondingmentioning

confidence: 99%

“…Therefore, to obtain a high-quality Cu/polymer interface, the following multiple processing steps are required: 1) polymer's CMP covered on Cu, 2) aggressive CMP to lower the height of Cu, and 3) fine CMP to secure the roughness of Cu. [32] The high viscosity of the polymer may inhibit slurry flow. In the CMP process, the slurry can be delivered either by flowing in from the side or dragging through a pad groove.…”

Section: Polymer Cmp Issuesmentioning

confidence: 99%

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Advanced Cu/Polymer Hybrid Bonding System for Fine‐Pitch 3D Stacking Devices

Park

Kang

Kim

et al. 2023

Adv Materials Technologies

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Hybrid bonding enables the commercialization of ultra‐fine pitch high‐density 3D packages. Cu/SiO2 hybrid bonding is the standard packing interface recently introduced in the industry. Here, the Cu/polymer hybrid bonding interface beyond Cu/SiO2 is proposed in order to have high compatibility for additional processes in the future. Ideally, polymers can provide excellent bonding strength and low permittivity, enabling high‐speed signal transmission with high reliability. To realize it, optimum polymer and additives selection and polymer bonding processing development are needed to get the desired packaging interface. Therefore, detailed materials and processing challenges are discussed to realize the successful Cu/polymer hybrid bonding. Then, the authors’ preliminary results are suggested to supplement the feasibility of the emerging bonding technology.

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Section: Challenges Of Cu/polymer Hybrid Bondingmentioning

confidence: 99%

Section: Process Of Cu/polymer Hybrid Bondingmentioning

confidence: 99%

Section: Polymer Cmp Issuesmentioning

confidence: 99%

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Advanced Cu/Polymer Hybrid Bonding System for Fine‐Pitch 3D Stacking Devices

Park

Kang

Kim

et al. 2023

Adv Materials Technologies

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“…The (111)-oriented nt-Cu was fabricated by electroplating. This research can provide helpful information to improve the current Cu/dielectric hybrid bonding technology using the high-CTE dielectrics, such as polyimide (PI) [ 35 ], polybenzoxazole (PBO) [ 36 ], benzocyclobutene (BCB) [ 37 ], and epoxy thermosets [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanisms of Cu–Cu Bumps under Thermal Cycling

Shie

Hsu

et al. 2021

Materials

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The failure mechanisms of Cu–Cu bumps under thermal cycling test (TCT) were investigated. The resistance change of Cu–Cu bumps in chip corners was less than 20% after 1000 thermal cycles. Many cracks were found at the center of the bonding interface, assumed to be a result of weak grain boundaries. Finite element analysis (FEA) was performed to simulate the stress distribution under thermal cycling. The results show that the maximum stress was located close to the Cu redistribution lines (RDLs). With the TiW adhesion layer between the Cu–Cu bumps and RDLs, the bonding strength was strong enough to sustain the thermal stress. Additionally, the middle of the Cu–Cu bumps was subjected to tension. Some triple junctions with zig-zag grain boundaries after TCT were observed. From the pre-existing tiny voids at the bonding interface, cracks might initiate and propagate along the weak bonding interface. In order to avoid such failures, a postannealing bonding process was adopted to completely eliminate the bonding interface of Cu–Cu bumps. This study delivers a deep understanding of the thermal cycling reliability of Cu–Cu hybrid joints.

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