Use of Laser Direct-Write in Microelectronics Assembly

The use of a laser-based direct-write (LDW) process is presented for the transfer of unpackaged semiconductor bare die for microelectronics assembly applications. Previous work using LDW techniques at the Naval Research Laboratory had been aimed towards demonstrating the use of a laser-based microfabrication process for direct-writing the materials required for the fabrication of microelectronic components such as interconnects, passives, antennas, sensors and power sources. Recently, we have applied the LDW process in forward-transfer mode to the release and transfer of single devices, such as semiconductor bare die, inside a pocket or recess in a substrate, thus performing the same function as pick-and-place machines used in circuit board assembly. The use of this technique is ideally suited for the assembly of microelectronic components and systems while allowing the overall circuit design and layout to be easily modified or adapted to any specific application or form factor. This paper presents examples of how the LDW process can be used as an effective laser die transfer tool and analysis of the laser-driven release process as applied to various types of silicon bare dies.