Thermosonic direct Cu pillar bonding for 3D die stacking

Roshanghias, Ali; Rodrigues, Augusto; Schwarz, Sabine; Steiger‐Thirsfeld, Andreas

doi:10.1007/s42452-020-2887-9

Cited by 13 publications

(3 citation statements)

References 18 publications

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“…Notably, the here employed power densities and pulse durations for US-supported TLP bonding are considerably lower compared to the previously reported approaches, and are similar to parameters as used in electronics for die attach by thermosonic flip-chip bonding. [37,49] Hence, US-supported TLP bonding with low-power US represents a promising method for manufacturing of joints with superior temperature stability and strength for electronics and other fields of application.…”

Section: Effect Of Us Application Upon Tlp Bondingmentioning

confidence: 99%

Fast and Reliable Ag–Sn Transient Liquid Phase Bonding by Combining Rapid Heating with Low-Power Ultrasound

Rheingans

Jeurgens

Janczak‐Rusch

2022

Metall Mater Trans A

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Ag–Sn transient liquid phase (TLP) bonding is capable of producing joints with excellent mechanical and thermal properties, and with operation temperatures at or even above the processing temperature. However, reduction of the comparatively long processing times required to achieve high-quality joints is highly desirable. To this end, the use of fast heating and low-power ultrasonic (US) pulses for accelerated Ag–Sn TLP bonding is investigated with particular focus on defect generation and avoidance. Employing rapid heating with $$20\,{\text {K s}}^{-1}$$ 20 K s - 1 , the process time can indeed be strongly reduced, yielding a high average shear strength of $$(58 \pm 22)$$ ( 58 ± 22 ) MPa. The large variance of the shear strength is caused by gas entrapment and pronounced lateral squeeze-out of liquid Sn, facilitated by the suppression of $${\text{Ag}}_{3} {\text{Sn}}$$ Ag 3 Sn formation upon rapid heating. Introduction of a weak US pulse leads to enhanced $${\text{Ag}}_{3} {\text{Sn}}$$ Ag 3 Sn formation and efficient removal of entrapped gas, and thus to avoidance of large-scale bond defects, which results in an enhanced shear strength of $$(104 \pm 8)$$ ( 104 ± 8 ) MPa.

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Section: Effect Of Us Application Upon Tlp Bondingmentioning

confidence: 99%

Fast and Reliable Ag–Sn Transient Liquid Phase Bonding by Combining Rapid Heating with Low-Power Ultrasound

Rheingans

Jeurgens

Janczak‐Rusch

2022

Metall Mater Trans A

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“…Another major advantage of this technique is that it provides the shortest conductor path essential for the high-frequency application. Flip-chip bonding can be performed by using only temperature (for solder bumps), thermo-compression (mainly assisted by conductive adhesives), or by using thermosonic energy (for Au and Cu bumps) [17]. The thermosonic flip-chip process has the advantage of low bonding force, low temperature, and short bonding time yielding a strong metallurgical joint [18,19].…”

Section: Flip Chip Integration Of the Thinned Chipsmentioning

confidence: 99%

Die-Level Thinning for Flip-Chip Integration on Flexible Substrates

et al. 2022

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Die-level thinning, handling, and integration of singulated dies from multi-project wafers (MPW) are often used in research, early-stage development, and prototyping of flexible devices. There is a high demand for thin silicon devices for several applications, such as flexible electronics. To address this demand, we study a novel post-processing method on two silicon devices, an electrochemical impedance sensor, and Complementary Metal Oxide Semiconductor (CMOS) die. Both are drawn from an MPW batch, thinned at die-level after dicing and singulation down to 60 µm. The thinned dies were flip-chip bonded to flexible substrates and hermetically sealed by two techniques: thermosonic bonding of Au stud bumps and anisotropic conductive paste (ACP) bonding. The performance of the thinned dies was assessed via functional tests and compared to the original dies. Furthermore, the long-term reliability of the flip-chip bonded thinned sensors was demonstrated to be higher than the conventional wire-bonded sensors.

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“…Thermosonic Cu bonding was facilitated by lower bonding forces and a shorter process. 14 The second approach was to implement a planarization process (fly-cutting) on Cu pillars prior to bonding. As a result, Cu pillars with a flattened surface and a uniform thickness distribution through the wafer were generated.…”

mentioning

confidence: 99%

3D Integration via D2D Bump-Less Cu Bonding with Protruded and Recessed Topographies

Roshanghias

Kaczynski

Rodrigues

et al. 2023

ECS J. Solid State Sci. Technol.

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Bump-less copper (Cu) bonding is currently the most attractive approach for fine-pitch (< 20 µm) 3D integration due to its compatibility with the wafer back-end-of-the-line fabrication process. In this study, themocompression bonding of bump-less Cu pads with a diameter of 4 µm and a pitch size of 10 µm was pursued, while chemical mechanical polishing (CMP)-processed Cu pads enclosed in SiO2 were employed with both protruded and recessed topographies. The effects of Cu topography (protruded or recessed) and bonding temperature on the electrical and microstructural properties of the die bonds as well as mechanical bonding strength were investigated. It was found that thermocompression bonding of CMP-processed Cu can be realized at shorter processing times, lower bonding temperatures, and pressures than standard electroplated Cu bonding. The bonding yield of the three configurations, i.e. protruded-protruded, protruded-recessed, and recessed-recessed Cu pads was also compared.

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Thermosonic direct Cu pillar bonding for 3D die stacking

Cited by 13 publications

References 18 publications

Fast and Reliable Ag–Sn Transient Liquid Phase Bonding by Combining Rapid Heating with Low-Power Ultrasound

Fast and Reliable Ag–Sn Transient Liquid Phase Bonding by Combining Rapid Heating with Low-Power Ultrasound

Die-Level Thinning for Flip-Chip Integration on Flexible Substrates

3D Integration via D2D Bump-Less Cu Bonding with Protruded and Recessed Topographies

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