3D Integration

Electronic devices have been evolving for the past few decades to enrich people’s lives. Moreover, they are expected to become the key contributor for SDGs. However, the latest and scaled logic device (CPU) can only be fabricated by a few “big” device companies or foundries who possess mega-fab with extremely expensive manufacturing tools (e.g. EUV).

Three-dimensional (3D) integration has the potential to overcome the limitations inherently introduced by the scaling of devices.

3D Integration chip

3D heterogeneous devices

Advanced applications such as, automated-vehicles, beyond 5G, telemedicine, etc…, cannot be realized by an electronic device. Several electronic devices (CPU, memory, Analog, Photonics, … and even quantum!) need to be closely linked and comunicated. That type of device is so-called “3D heterogeneous integration”

We mainly look into the fabrication processes for the heterogeneous integration.


Detailed research topics

1.Hybrid bonding (Direct bonding)

Hybrid bonding is a promising direct wafer bonding approach which creates mechanical joints (dielectric-dielectric) and electrical connections (Cu-Cu) simultaneously. In addition, additional spacing is not required for through-Si via (TSV) landing, which is essential for direct wafer bonding with the punch-through via-last TSV approach. The higher flexibility of the system design allowed by hybrid bonding enables us to make higher-density connections for the top and bottom wafers. In hybrid bonding, two wafers are finished by a Cu/dielectric damascene process with atomic-scale dielectric surface roughness and minimal Cu protrusion/recess.

We have research capabilities for “electrodeposition”, “polishing” and “direct bonding” in our lab, which is quite unique in the world.


2.Area-selective deposition (ALD, SAM, ELD, EL-ALD)

In the near future, self-assembling will be essential for electronic device manufacturing. With “atomic level” deposition method such as SAMs, ELD, e-ALD, EL-ALD, we will develop the next generation of nano-fabrication techniques.

3.Novel direct bonding application

We also investigate fabrication processes which can be used for novel devices, such as 3D photonics, 3D power device and 3D quantum computing.