Chapter 9
Copper Micro and Nano Particles
Mixture for 3D Interconnection
Application
Yuanyuan Dai and Chuan Seng Tan
9.1 Introduction
There are several types of commonly used wafer bonding technologies such as direct
wafer bonding, eutectic bonding, anodic bonding, and direct metal bonding [1].
For metal bonding, the choice of a suitable material as interconnect is important.
The desirable material should have high electrical conductivity. Table 9.1 shows the
properties of some competitive candidates for comparison. Since silver has promising
electrical conductivity, it is widely used as metal bonding layer [2–4]. Aluminium,
copper, gold and their alloys are also listed as competitive interconnections [5–9].
Table 9.2 shows the eutectic temperature of some commonly used alloys.
For power electronic devices, the electrical conductivity draws more attention.
Thus, silver serves a popular material as interconnection. However, as the cost of
silver is high, it is less attractive for industrial scale production. Alternatively, copper
has a much lower cost than silver and gold, and displays a better electrical conductivity than aluminum. Hence, copper emerges as a promising metal of choice [14–16].
However, several challenges exist in the sintering process since copper has a relatively
high melting point.
9.1.1 A Review of Metal Nano-Particles Bonding
Metallic particles are good solution since they offer a low sintering temperature. This
is because the surface-volume ratio increases with smaller particle size such that it
Y. Dai · C. S. Tan (B)
Nanyang Technological University, Singapore, Singapore
e-mail: tancs@ntu.edu.sg
© The Editor(s) (if applicable) and The Author(s), under exclusive
license to Springer Nature Singapore Pte Ltd. 2021
Y. Li and D. Goyal (eds.), 3D Microelectronic Packaging,
Springer Series in Advanced Microelectronics 64,
https://doi.org/10.1007/978-981-15-7090-2_9
233
Copper Micro and Nano Particles
Mixture for 3D Interconnection
Application
Yuanyuan Dai and Chuan Seng Tan
9.1 Introduction
There are several types of commonly used wafer bonding technologies such as direct
wafer bonding, eutectic bonding, anodic bonding, and direct metal bonding [1].
For metal bonding, the choice of a suitable material as interconnect is important.
The desirable material should have high electrical conductivity. Table 9.1 shows the
properties of some competitive candidates for comparison. Since silver has promising
electrical conductivity, it is widely used as metal bonding layer [2–4]. Aluminium,
copper, gold and their alloys are also listed as competitive interconnections [5–9].
Table 9.2 shows the eutectic temperature of some commonly used alloys.
For power electronic devices, the electrical conductivity draws more attention.
Thus, silver serves a popular material as interconnection. However, as the cost of
silver is high, it is less attractive for industrial scale production. Alternatively, copper
has a much lower cost than silver and gold, and displays a better electrical conductivity than aluminum. Hence, copper emerges as a promising metal of choice [14–16].
However, several challenges exist in the sintering process since copper has a relatively
high melting point.
9.1.1 A Review of Metal Nano-Particles Bonding
Metallic particles are good solution since they offer a low sintering temperature. This
is because the surface-volume ratio increases with smaller particle size such that it
Y. Dai · C. S. Tan (B)
Nanyang Technological University, Singapore, Singapore
e-mail: tancs@ntu.edu.sg
© The Editor(s) (if applicable) and The Author(s), under exclusive
license to Springer Nature Singapore Pte Ltd. 2021
Y. Li and D. Goyal (eds.), 3D Microelectronic Packaging,
Springer Series in Advanced Microelectronics 64,
https://doi.org/10.1007/978-981-15-7090-2_9
233