Packaging in the Nanotechnology Era
05/01/2005
Recent scientific breakthroughs in nanotechnology are anticipated to provide the most significant disruptive technologies since the Internet. With all of the possibilities that nanotechnology provides, and the significant potential for novel materials and ICs coming from this area, it is imperative to consider the effects that these might have on the world of device packaging.
Near-term implications of nanotechnology that already can be seen include new, stronger materials for packaging structures, enhanced heat transfer and heat spreading materials, and needs for new design and manufacturing capabilities to exploit opportunities that arise as a consequence of developments in nanotechnology. In the long term, nanotechnology is expected to require significant changes in packaging as new structures, possibly exploiting novel material properties resulting from the use of nanotechnology materials, are introduced in place of current circuit components. Initial needs are anticipated to be capabilities to accommodate structures such as carbon nanotubes in transistor channels or, possibly, molecular switches in place of the current basic transistor switch. In the long term, nanotechnology promises to have an even more significant impact on packaging as entirely new device types, and possibly new computation formats, become useful.
The most widely anticipated material being considered for use in various devices, as well as packaging approaches, is carbon nanotubes. It may be that this is the most widely discussed material in the new nanotechnology domain because it has had the longest period of exposure, but it does have the clear advantages of being 100x stronger than steel, at 1/6 the weight, conducting electricity better than many metals and conducting heat better than diamond. All of these attributes are causing this material to be considered for use in both passive and active parts of devices and packaging. Possibilities that have been discussed include: using the structural strength of carbon nanotubes to add significant strength while reducing weight in packaging materials; using the favorable thermal conductivity of carbon nanotubes as an enhancement in thermal interface materials; and using the favorable electrical conductivity of carbon nanotubes to provide novel, high-performance conduction paths both within packages and from package to external pins.
The real challenge of nanotechnology from a packaging viewpoint, of course, will come when circuits using nanotechnology components begin to be manufactured. Even though these circuits may be different than today’s silicon ICs, they will still need packaging to provide protection from the environment and the transformation from the nanoscale dimensions of the circuit to the dimensions of the macroscopic world where the circuits are applied. In this new case, however, this may be a much more difficult packaging task than in the past. It is likely that, as in the case of carbon nanotubes, the significant differences in electrical properties that make materials used in nanotechnology advantageous for new circuit applications will be accompanied by equally novel mechanical and thermal properties. The consequences and susceptibilities of these new materials and structures will need to be comprehended in the materials selections and process steps used in packaging these new circuits. For example, it is likely that at some point conventional silicon circuitry will be enhanced in some way by the addition of organic components. This enhancement may be to provide better performance, but it is much more likely to be to provide unique functionality for some new applications, such as sensors. In this case, the complexities of maintaining structural integrity, ensuring electrical contacts, and accounting for long-term reliability in the face of the relatively severe thermal and mechanical stresses associated with today’s packaging processes and materials are enormous.
The question is, will the packaging community be ready to solve the technical problems and environmental challenges required to assimilate the structures and materials of the nanotechnology era into packages in a time commensurate with the market needs? Thus far, the possible packaging problems associated with circuits using nanotechnology components have not been a priority. This may be because even though large amounts of R&D funding are now being applied to find practical applications of nanotechnology, it has been found to pose scientific challenges that may lead to a longer incubation period and commercialization process than what early proponents anticipated. It would only take one significant breakthrough, however, to suddenly create a major opportunity that can be exploited. It is critical that adequate effort be applied to new R&D of packaging options so that the market window for such an opportunity is not lost for lack of a package!ap
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HAROLD HOSACK, Ph.D., director of Interconnect Packaging Sciences, may be contacted at Semiconductor Research Corp., PO Box 12053, Research Triangle Park, NC 27709-2053; (919) 941-9485; e-mail: [email protected].