Tuesday, January 26, 2010

UCF Unveils New Carbon Nanotube Reinforced Metal Nanocomposite Material for Integrated Circuit Fabrication

University of Central Florida (UCF) Research Foundation, Inc. (Orlando, FL) earned U.S. Patent 7,651,766 for carbon nanotube reinforced metal nanocomposite material and a process for manufacturing the composite.    

FIG. 2 is a scanned SEM image of an electrochemically co-deposited copper/SWNT nanocomposite SWNTs  can be seen to be covered uniformly by copper that forms the continuous phase. The SWNTs can be seen to be somewhat aligned in the Cu matrix. The uniformity in coverage with stiff and conductive copper better utilizes the properties of the SWNTs, as compared to conventional carbon nanotube polymer composites.

Carbon nanotube reinforced metal nanocomposites provide thermal conductivity and electrical conductivity which are generally significantly higher than the pure metal continuous phase material, mechanical strength is 2 to 3 times greater than that of the pure metal, and a tailorable coefficient of thermal expansion (CTE) is obtainable through changing the percentage of nanotubes in the nanocomposite. The material can be designed to match the CTE for a variety of materials of interest, including most semiconductors and electrically insulating (dielectric) substrates.

The composite includes a continuous metal phase, and a plurality of carbon nanotubes dispersed in the continuous metal phase, according to inventor UCF Department of Mechanical, Materials and Aerospace Engineering Professor Quanfang ChenThe metal phase material is preferably copper.

The metal phase extends throughout substantially an entire thickness of the nanocomposite material. The nanotubes are preferably single wall nanotubes (SWNTs). The carbon nanotubes are preferentially aligned in the continuous metal phase, such as generally along a given direction. The nanocomposite is generally exclusive of any material other than the metal or metal alloy and the nanotubes.

The carbon nanotube reinforced metal nanocomposites are preferably formed using an electrochemical co-deposition process in which both the nanotubes and the metal ions to be electrodeposited are in an electrolyte comprising solution. This process advantageously can be performed at or near room temperature, such as less than or equal to about 50.degree. C., and is thus compatible with a wide variety of processes and associated materials. The process is capable of being scaled for large area substrates and deposition on multiple substrates simultaneously.

Electro co-deposition of the carbon nanotube can be integrated with many integrated circuit fabrication processes including damascene processes used in state-of-the-art IC fabrication processes to form electrically conductive interconnects and other electrically conductive layers (e.g. contacts and/or metal gates). Another advantage of the electrochemical co-deposition process is that carbon nanotubes are not measurably degraded by the inventive co-deposition process and better interfacial bonding is obtained, due to the low temperature and better wetting characteristics.   

FIG. 1, a schematic representation of an exemplary electrochemical co-deposition apparatus for producing the carbon nanotube nanocomposites. Carbon nanotube reinforced copper nanocomposites were formed using the electro co-deposition process

FIG. 3(A) is a sketch of SWNTs preferentially aligned in a particular direction in a Cu comprising electrolyte solution while FIG. 3(B) is a scanned SEM photograph which shows a nanocomposite in which SWNTs are preferentially aligned in a particular direction in a Cu comprising continuous phase (matrix), thus demonstrating that carbon nanotubes can be aligned within a metal matrix

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