Surface Passivation of Cu for Low Temperature 3D Wafer Bonding

Lim, D. F.; Wei, Jun; Leong, K. C.; Tan, Chuan Seng

doi:10.1149/2.013201ssl

Cited by 11 publications

(3 citation statements)

References 8 publications

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“…This has been confirmed in a separate thermal aging study by Kumbhat et al [4]. Moreover, the outward diffusion of Au atoms into Cu was blocked by the Ni barrier layer, stopping the formation of Kirkendall voids arising from Au-Cu interdiffusion [19]. Experimental correlation between the bonding times and temperature for Au direct bonding has been illustrated by Tong [9].…”

Section: Bonding Interface Characterization and Mechanismsmentioning

confidence: 68%

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch

Wang

Smet

Kobayashi³

et al. 2014

2014 IEEE 64th Electronic Components and Technology Conference (ECTC)

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This paper reports the first design and demonstration of a manufacturable 20 µm pitch Cu interconnection technology to ultra-thin glass interposers. Bonding is accomplished at temperatures below 200 o C without the need for solders. Manufacturability challenges such as substrate warpage, bump noncoplanarity and assembly throughput with low bonding times are addressed with this technology. The modeling and experimental results indicate that the ultra-fine pitch Cu interconnection offsets more than 3 µm non-coplanarity. Bonding interfaces were characterized to show that metallurgical bonding microstructure is formed even with a bonding time of 5 seconds, with superior electrical properties. A mechanism for low-temperature metallurgical bonding is proposed based on the characterization results.

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Section: Bonding Interface Characterization and Mechanismsmentioning

confidence: 68%

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch

Wang

Smet

Kobayashi³

et al. 2014

2014 IEEE 64th Electronic Components and Technology Conference (ECTC)

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show abstract

“…A desorption temperature of 250 °C is also used in other studies [ 17 , 22 , 46 , 47 ]. A certain amount of O content is still present at the bonding interface even after desorption in one of these reports [ 22 ].…”

Section: Resultsmentioning

confidence: 99%

Cu-Cu Thermocompression Bonding with a Self-Assembled Monolayer as Oxidation Protection for 3D/2.5D System Integration

et al. 2023

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Cu-Cu direct interconnects are highly desirable for the microelectronic industry as they allow for significant reductions in the size and spacing of microcontacts. The main challenge associated with using Cu is its tendency to rapidly oxidize in air. This research paper describes a method of Cu passivation using a self-assembled monolayer (SAM) to protect the surface against oxidation. However, this approach faces two main challenges: the degradation of the SAM at room temperature in the ambient atmosphere and the monolayer desorption technique prior to Cu-Cu bonding. In this paper, the systematic investigation of these challenges and their possible solutions are presented. The methods used in this study include thermocompression (TC) bonding, X-ray photoelectron spectroscopy (XPS), shear strength testing, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The results indicate nearly no Cu oxidation (4 at.%) for samples with SAM passivation in contrast to the bare Cu surface (27 at.%) after the storage at −18 °C in a conventional freezer for three weeks. Significant improvement was observed in the TC bonding with SAM after storage. The mean shear strength of the passivated samples reached 65.5 MPa without storage. The average shear strength values before and after the storage tests were 43% greater for samples with SAM than for the bare Cu surface. In conclusion, this study shows that Cu-Cu bonding technology can be improved by using SAM as an oxidation inhibitor, leading to a higher interconnect quality.

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“…Specific pre-bonding surface conditioning is necessary to ensure high bonding quality of patterned Cu wafers using Cu-Cu non-thermo compression bonding for wafer-to-wafer 3D stacking. Surface preparations for the hybrid fusion bonding such as removal of Cu oxide, Cu surface protection and optimized CMP planarization patterned Cu surfaces have been studied [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Surface Inspection of Cu-Cu Non-Thermal Compression Bonding for Wafer-to-Wafer 3D Stacking

et al. 2014

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Surface Passivation of Cu for Low Temperature 3D Wafer Bonding

Cited by 11 publications

References 8 publications

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch

Cu-Cu Thermocompression Bonding with a Self-Assembled Monolayer as Oxidation Protection for 3D/2.5D System Integration

Surface Inspection of Cu-Cu Non-Thermal Compression Bonding for Wafer-to-Wafer 3D Stacking

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Surface Passivation of Cu for Low Temperature 3D Wafer Bonding

Cited by 11 publications

References 8 publications

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 &#x03BC;m pitch

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 &#x03BC;m pitch

Cu-Cu Thermocompression Bonding with a Self-Assembled Monolayer as Oxidation Protection for 3D/2.5D System Integration

Surface Inspection of Cu-Cu Non-Thermal Compression Bonding for Wafer-to-Wafer 3D Stacking

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Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch

Modeling, design, and demonstration of low-temperature Cu interconnections to ultra-thin glass interposers at 20 μm pitch