Electeodeposited metal structures in high aspect ratio cavities using vapor deposited polymer molds and laser micromachining

This paper reports a laser-assisted fabrication scheme for three-dimensional (3-D) electrodeposited metal structures into high aspect ratio trenches. A polymer (parylene C) is conformally deposited onto a highly nonplanar surface, selectively laser ablated, and used as an electroplating mold to fabricate metallic structures. Laser ablation of high-resolution (< 10μm) features is performed using a 248nm KrF Excimer laser. The ablation parameters for the parylene layer have been characterized for various film thicknesses. Metal lines of 2μm thickness, and 2.5μm width have been electroplated into 300μm deep silicon trenches. The minimum resolution achieved is less than 5μm. This process can potentially be applied toward the fabrication of embedded inductors, high density electrodes, buried interconnects or high voltage circuitry in CMOS and MEMS devices.