Low-Profile Interconnects via Laser-Induced Forward Transfer

Direct-write processes offer several advantages over traditional lithographic techniques, including high processing speeds, high resolution, and the ability to fabricate complex 2D and 3D structures. Specifically, laser-induced forward transfer (LIFT) is a non-lithographic process that can be utilized to efficiently print numerous materials on various substrates with high precision. By using high viscosity nanopastes, structures can be printed with high positional accuracy that maintain the shape of the spatially structured laser beam. This capability lends itself to applications such as sensors and microelectronic components requiring features with narrow pitch. Because of the versatility of the LIFT process, interconnects can be printed directly onto the bond pads of both flip-chip devices in addition to directly onto substrates. In this work, we demonstrate the use of LIFT for printing high-aspect ratio vertical micro-pillars combined with freestanding voxels to fabricate low profile interconnects on a bare die LED.