Laser processing of 3-D structures for embedded and integrated components: An application of flexible and printable nanomaterials in microelectronics

This paper discusses laser processing of polymer nanocomposites and sol-gel thin films. In particular, recent developments on vertical multilayer embedded capacitors are highlighted. A variety of flexible, transperent nanocomposite thin films ranging from 2 microns to 25 microns thick were processed on copper, or ITO, or organic substrates by large area (330 mm x 470 mm, or 495 mm x 610 mm) liquid coating processes. A frequency-tripled Nd:YAG laser operating at a wavelength of 355 nm was used for the micromachining study. The micromachining was used to generate arrays of variable-thickness capacitors from the nanocomposites. The resultant thickness of the capacitors depends on the number of laser pulses applied. Laser micromachining was also used to make long, deep multiple channels from a capacitance layer. Spacings between two channels act as individual vertical capacitors, and parallel connection eventually produces vertical multilayer capacitors. Optical phototgraphs and SEM micrographs were used to view spacings/channels in the coatings. In the case of sol-gel thin films, micromachining results in various surface morphologies. It can make a "wavy" random 3-D structure, or can make an array of regular 3D patterns (spirals/lines) depending on laser fluence. Altogether, this is a new direction for development of multifunctional nanomaterials.