Ni-Sn SLID bonds for assembly at extremely high temperatures

Ni-Sn solid-liquid interdiffusion bonding (SLID) has shown potential for assembly of materials in high-temperature applications up to 600^{\circ}\mathrm{C}. This paper attempts to fabricate a bond with a specific intermetallic phase of Ni_{3} Sn_{2} to push the temperature stability to 1000^{\circ}\...

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Bibliographic Details
Published in2021 23rd European Microelectronics and Packaging Conference & Exhibition (EMPC) pp. 1 - 5
Main Authors Kuziora, Stephane Leonard, Nguyen, Hoang-Vu, Aasmundtveit, Knut Eilif
Format Conference Proceeding
LanguageEnglish
Published IMAPS-Europe 13.09.2021
Subjects
Analytical models
Annealing
Bonding
high temperature
Intermetallics
Metallization
Ni-Sn
Nickel
Silicon
SLID
Thermomechanical processes
TLP
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Summary:Ni-Sn solid-liquid interdiffusion bonding (SLID) has shown potential for assembly of materials in high-temperature applications up to 600^{\circ}\mathrm{C}. This paper attempts to fabricate a bond with a specific intermetallic phase of Ni_{3} Sn_{2} to push the temperature stability to 1000^{\circ}\mathrm{C}. Experiments were conducted using Si/TiW(10:90)/Ni/Sn dies where a two-step bonding process was used. The first step was bonding at 285^{\circ}\mathrm{C} for 5 hours. The bonded dies showed fractures perpendicular to the bonding plane indicating significant thermomechanical tensile forces. The initial voiding was 5% less than theoretically expected. The second step was annealing at 600^{\circ}\mathrm{C} for 1 hour and 3 hours, resulting in the final bonds with a layered structure of Ni/Ni_{3} Sn/Ni_{3} Sn_{2} /Ni_{3} Sn_{4} /Ni_{3} Sn_{2} /Ni_{3} Sn/Ni. The bonds after 3 hours annealing had no remaining Ni. New fractures along the bonding plane appeared propagating through the remaining Ni_{3} Sn_{4} indicating large thermomechanical shearing forces. Voiding increased by a further 6% after the 1 hour anneal. For the bonds with 1 hour anneal, the new voids were seen at the Ni_{3} Sn_{4} /Ni_{3} Sn_{2} interface and at the Ni 3 Sn/Ni interface. The growth constant for Ni_{3} Sn_{2} at 600^{\circ}\mathrm{C} was 3.5\mu m/min^{n}, while the growth exponent was 0.2 giving a homogenization time of \sim 60 hours for the experimental bondline thickness of 38\mum. Thus, larger annealing temperatures or times are needed to accelerate bonding.
DOI:10.23919/EMPC53418.2021.9584973