Heterogeneous Integration Technologies

RESEARCH FOCI

• Multiphysics/Co-Simulation of 3D integrated “More-than-Moore” systems e.g. to reduce cross-sensitivity; identify hot spots for improved functionality.
• Packaging research for sensors and MEMS involves the optimization of the mechanical and electrical interface specific to the application, especially high temperature environments.
• Packaging and Integration for smart systems is the specific integration of miniaturized sensors in existing products realizing a smart system.
• Research on ink-jet and 3D printing technologies leading to maskless and customizable deposition on wafer/chip/package level and rapid prototyping packages

RESEARCH COMPETENCIES

The Heterogeneous Integration Technologies team involves interdisciplinary competences of material science, microsystems technologies, physics, mechatronics as well as fluid and structural FEM simulation experts. Like the challenges in the field of packaging and integration are multidisciplinary so the team reflects the necessary competences. The HIT area has access to a 100m2 C8 clean room at the premises with state-of-the-art packaging equipment, which is constantly enhanced according to project demand. In addition, novel ink-jet printing technologies together with photonic curing equipment is available for the research of additive manufacturing technologies in the context of packaging and assembly.

• Packaging and µ-assembly
  • Die bond (Adhesive bonding, Transient liquid phase bonding, Nano-particle sinter bonding, Flip-Chip)
  • Wire bond (Wedge /wedge (Al, Au, Pt, Ag))
• Multi-physics simulation (Co-Simulation):  Thermo-mechanical simulation, Magnetic simulation, CFD simulation
• Additive Manufacturing (3D and Ink-jet print): Printing of polymer package prototypes, Ink-jet di-electric / metallization schemes
• Characterization & Test: Environmental testing, Bond characterization, MSA characterization

APPLICATIONS

FEM simulation of a 3D integrated power package

With the help of FEM Multiphysics simulation the continuous miniaturization of electronic systems can be enabled and evaluated Novel 3D integrated package concepts are characterized by a very high functional density, leading to thermal considerations inside the structure. These results gave important indications for process variants and metals used to build the 3D structure. In this example conducted within the EPPL project a 3D power package was investigated for heat flow and possible hot spots inside the structure.

LiNbO3 die-attach with Au-Ge eutectic solders

The packaging process of chips is crucial for the lifetime in the specific operating conditions. This is even more challenging in high temperature environments. Chip packages have to cope in high operating temperatures, but to avoid degradation of the chip also the bonding temperature has to be kept as low as possible. In the shown example the operating temperature is up to 300 °C, but the processing temperature should be kept below 450 °C due to the increasing decomposition of the die. As a solution a eutectic alloy was used. When the Au-12Ge alloy, melts in contact with Au metallization finish, the resulting die-attach joint will have a melting point higher than the eutectic point due to the diffusion of Au into the bond layer. The higher re-melting point of the die-bond leads to the intended stability at high operating temperatures.