Metal plating is a material processing technique key to a wide range of electronics applications, from fabrication of semiconductor devices and telecommunication fibers to device enhancement (via anti-corrosion and anti-wear protective coatings). Existing commercial techniques are limited in their versatility of materials and geometries that can be plated effectively and often, for certain materials, rely on harsh methods to overcome these limitations. The new technology described here provides several novel, comprehensive and versatile solutions for controlled metal plating. This electroplating system combines laser irradiation, optical lenses and mirrors and optical fibers to remove native oxides from metals, effectively plate, pattern and simultaneously anneal a variety of metals and geometries while in certain cases combining this with sensitive monitoring processes.. This technology can also be used to economically achieve reel-to-reel metal depositions that yield continuous or quasi continuous substrates with superior electrical and mechanical properties without the need for the use of harsh manufacturing chemicals and laboratory conditions.
This technology utilizes locally directed laser irradiation to remove oxide layers, particularly, though not exclusively, from aluminum, where oxidation occurs even under ambient conditions. The thin oxide layers inhibit both electroplating and etching. This in situ laser oxide removal can be performed quickly and robustly on many metals, in vacuum followed by immersion in an electrolyte, under inert gas, or immersed within the electrolyte with the laser penetrating through the electrolyte without the high temperatures and harsh conditions that plague traditional oxide removal methods. Electroplating or electroless plating promptly follows within the same aforementioned systems, unlike traditional methods that require several intermediate steps. Mirrors and lenses can be adjusted to control the angular orientation of laser irradiation on the metal surface giving rise to a maskless pattern plating/etching, also facilitating irradiation of non-planar surfaces; allowing, for instance, plating of aluminum-copper wires and the inside of hollow metal tubes that may be critical for high-frequency transmission applications. This technology thus has an added versatility over traditional methods, which can generally best accommodate planar geometries.
A separate part of this general technology also incorporates a compact, highly sensitive microfluidic system for monitoring electrolyte composition and deposition rates for quality assurance. Through the design of the microchannels and incorporated electrochemical measurements, small volumes of electrolyte solution are sufficient to characterize the system in a short time. In contrast, existing methods rely on bulky systems that require large quantities of electrolyte solution and long acquisition times to achieve needed sensitivity.
Another aspect of the Columbia technology incorporates a means for slowly annealing a metal deposition, of particular interest, gold (with vast applications for electronic connectors) during the deposition. The slow annealing during growth allows for layer by layer annealing. This can be accomplished by means of scanning a low power across the film during deposition. It can also be achieved by means of electrically pulsing the substrate material during deposition. This latter technique is especially suitable for electroless plating. These annealing techniques during growth of the material allow for better controlled structural growth, which can yield thinner, lower porosity (and thus less corrosive) desirable films, reducing material wastage, production costs, thereby yielding more structurally sound material (deposits).
Alan C. West, Ph.D. Robert J. von Gutfeld, Ph.D.
Issued Patent (US 8,475,642)
Issued Patent (US 8,496,799)
Patent Pending (US 20110042201)
Patent Pending (US 20110104396)
Available for licensing and sponsored research support
Tech Ventures Reference: IR M08-063, IR M05-055, IR M05-044, IR M08-017, IR M08-017a, IR M08-063, IR M10-023, IR M08-100