Achieving low-temperature wafer level bonding with Cu-Sn-In ternary at 150 °C

Golim, Obert P.; Vuorinen, Vesa; Ross, Glenn; Wernicke, Tobias; Pawlak, Marta; Tiwary, Nikhilendu; Paulasto‐Kröckel, Mervi

doi:10.1016/j.scriptamat.2022.114998

Cited by 12 publications

(4 citation statements)

References 13 publications

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“…These phases have the same crystal structures as the well-known Cu3Sn and Cu6Sn5 compounds with In atoms occupying the Sn sublattices [14]. In addition, O. Golim et al have successfully manufactured fine pitch Cu-Sn-In microbumps, demonstrating the possibility of Cu-Sn-In SLID bonds being as small as 10 µm [34]. Despite the numerous positive properties exhibited by Cu-Sn-In SLID, process integration for MEMS and the interconnect reliability have not been reported.…”

Section: Introductionmentioning

confidence: 92%

“…With excellent wetting properties on glass, quartz, and ceramic materials, they could be ideal for metal-to-non-metal joining [30]. Furthermore, the bonding temperature can be as low as 150 °C [34], and the remelting temperature exceeds 600 °C [21], as the bonding results in a fully formed IMC bond-line without any traces of unreacted low melting point material [34], [35], [36]. Two IMCs (Cu3(In,Sn) and Cu6(In,Sn)5) have been reported to form in reactions of InSn alloys with Cu at temperatures between 150 °C and 400 °C [37].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Emadi,

Vuorinen,

Liu

et al. 2024

Preprint

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In response to the evolving demands of microelectromechanical system (MEMS) integration, aiming to achieve high-performance electronic products, innovative interconnect solutions are becoming essential. The interconnects must possess key features, including the capability for miniaturization, low processing temperatures, and the ability to maintain a stable microstructure with optimized electrical, mechanical, and thermomechanical properties. To meet these demands, this study designed a novel Cu-Sn-based solid-liquid interdiffusion (SLID) interconnect. The study involved the implementation of a metallization stack, incorporating Co as a layer to interact with low-temperature Cu-Sn-In SLID and form intermetallic compounds (IMCs). Since Cu6(Sn,In)5 forms at a lower bonding temperature than other phases commonly observed in the Cu-Sn-In system, the study aimed to develop interconnects comprising a stable single-phase (Cu,Co)6(Sn,In)5. Bonding conditions were established for the Cu-Sn-In/Co system and the Cu-Sn/Co system as a reference. Thorough assessments of their thermomechanical reliability were conducted through hightemperature storage (HTS), thermal shock (TS), and tensile tests. The Cu-Sn-In/Co system emerged as a reliable low-temperature solution with the following key attributes: 1) a reduced bonding temperature compared to the Cu-Sn SLID interconnects, 2) the absence of the Cu3Sn phase and resulting void-free interconnects, and 3) high thermomechanical reliability, particularly following thermal annealing after bonding.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Emadi,

Vuorinen,

Liu

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…However, when the bonding temperature is ≤200°C the bond is composed of single phase Cu 6 (Sn,In) 5 , which doesn't transform to Cu 3 (Sn,In) even after extensive solid state annealing (>500h at 150°C) (3). In order to demonstrate that small µ-bonds can be manufactured at temperatures as low as 150°C Si wafers containing 10 µm-sized microbumps based on the Cu-Sn-In ternary system were fabricated with wafer-level bonding (5,6). The test wafers had symmetrical metallization structure of 4 µm Cu| 1,5 µm Sn|1,5 µm In.…”

Section: Auin Bondingmentioning

confidence: 99%

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

Wernicke,

Rebhan,

Vuorinen

et al. 2023

ECS Trans.

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An overview of various low temperature (<200°C) wafer bonding processes using metal interlayers is presented. Such processes are very attractive for novel applications in 3D heterogenous packaging as the allow for simultaneous formation of electrical interconnects, as well as hermetic encapsulation of various sensors and microelectromechanical systems-based devices. Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic alloy is formed as bonding layer during the process by liquid-solid interdiffusion), intermetallic wafer bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, process known also as Solid Liquid Intermetallic Diffusion – SLID or Transient Liquid Phase – TLP), and metal thermo-compression (TC) wafer bonding. Different critical/gating parameters were investigated and their impact for generally reducing processing temperatures for the different metal bonding systems was studied.

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“…Therefore, to better apply the advantages of the high-performance power components, alternative die-attach materials with the following characteristics are needed: 1) low bonding temperature to decrease the induced stresses and 2) efficient performance of high-temperature power devices under normal operating conditions. The low-temperature SLID bonding can typically be performed at a temperature close to 200°C or even below that [5], which means that the intrinsic stresses within the bond will be reduced compared to that at a higher temperature [6]. Additionally, the bond has a high melting point, even though it is formed at a low temperature.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature die attach for power components: Cu-Sn-In solid-liquid interdiffusion bonding

Emadi

Liu

Klami

et al. 2022

2022 14th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM)

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Based on the finite element (FE) simulations done in this work, lowering the bonding temperature significantly decreases the bonding induced residual stresses. Therefore, low temperature Cu-Sn-In SLID process was utilized to bond Si to Si and Si to sapphire under various bonding conditions. The microstructural evolution and the (thermo-) mechanical properties of the joints were studied. The results showed that the Cu-Sn-In SLID bonds composed of a single Cu6(Sn,In)5 IMC phase with high joint strength. Furthermore, the hardness and Young's modulus of Cu6(Sn,In)5 formed in the SLID bonding were measured to be slightly higher than that of binary Cu6Sn5.

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Achieving low-temperature wafer level bonding with Cu-Sn-In ternary at 150 °C

Cited by 12 publications

References 13 publications

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Novel low-temperature interconnects for 2.5/3D MEMS integration: demonstration and reliability

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

Low-temperature die attach for power components: Cu-Sn-In solid-liquid interdiffusion bonding

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