Lead Inventors:
Alan C. West, Ph.D.; Robert J. von Gutfeld, Ph.D.
Pattern etching in MEMS and integrated circuits without undercutting edges:
Integrated circuits and micro-electro-mechanical systems (MEMS) devices are typically fabricated by applying a pattern to a substrate surface and exposing it to chemicals that etch those parts of the surface that are exposed by the pattern. Most conventional chemical or electrochemical etchants remove material from a substrate surface isotropically, i.e., at the same rate in all directions. This causes undercutting below the edges of the pattern; the resulting walls of the etched volume consequently curve inward in a concave manner. To avoid this undercutting in circumstances when it may adversely affect the performance or structural integrity of the device or circuit being fabricated, anisotropic etching processes are used. Although such processes have been developed for crystalline substrates, there is a need for anisotropic etching processes that can be used to etch non-crystalline substrate materials such as metals.
Anisotropic heating of substrate surface to etch patterns while reducing undercut:
This technology comprises two systems for performing anisotropic etching of crystalline or non-crystalline substrates with chemical or electrochemical etchants whose etching rates are thermally activated. Both systems use anisotropic heating of the substrate surface to preferentially etch those parts of the substrate that are heated; this reduces the possibility that surfaces adjacent to those being etched will be undercut. One system applies heat to the substrate via pulsed high intensity current pulses passed through the substrate; the other applies heat via high intensity light pulses directed onto the surface of the substrate.
Applications:
-- The technology can be used to etch patterned substrates with reduced undercutting and more vertical walls than possible with standard isotropic etching processes.
Advantages:
-- The technology can be used to perform anisotropic etching of non-crystalline materials.
-- Circuit lines in boards etched with this technology exhibit lower resistance and higher structural integrity than those etched with isotropic processes because the vertical walls of the lines etched with this technology have vertical walls that are less undercut.
Patent Status: Patent Pending (US20080245674) ~ see link below.
Licensing Status: Available for Sponsored Research Support
