Vertical Laser Assisted Bonding for Advanced "3.5D" Chip Packaging

In this work the processes of laser assisted bonding (LAB) is compared to thermal compression bonding (TCB). Their respective advantages and disadvantages regarding the assembly of flip chip stacks are compared. It is found, that the LAB allows for faster processing, negligible compression force and creates less internal stress in the chip stack. The concept of "3.5D" stacking is introduced. This new concept allows for the vertical bonding of chips/semiconductors to the sides of a chip stack. The vertically bonded parts can be used to contact the individual layers, which eliminates the necessity for through silicon vias (TSVs).