Nanotechnology Research at UMass Amherst Leads to New Techniques For Semiconductor Manufacturing

AMHERST, Mass. – Research findings published by University of Massachusetts Amherst scientists demonstrate how nanotechnology can be used in the manufacturing of very small integrated circuits, using supercritical fluids to transfer the three-dimensional structure of polymer templates into rigid, ceramic-like films. The findings appear in the January 23, 2004 issue of Science.

As industry moves toward increasingly smaller dimensions for semiconductor chip making, materials that provide better electrical insulation for the intricate wiring structures are required. Rigid silicate films containing tiny pores are one solution being explored for fabrication of silicon-based structures for tomorrow’s electronic devices. At sizes in the range of billionths of a meter, manipulating the structure of these porous films is extremely difficult. Achieving the right balance of desired electrical, mechanical and thermal properties has been elusive at the scale-up and manufacturing stage. However, just as the growth patterns of bone and shell in biological systems use a molecular "template" to add new inorganic material to form a self-organized shape, scientists have sought to employ a similar approach in preparing templated materials for man-made devices using a rapid and effective self-assembly process. A challenge has been to integrate this approach with the rest of the chipmaking process for use in industrial production.

The technique outlined by James Watkins, associate professor of chemical engineering, and graduate student Rajaram Pai, begins with the creation of thin polymer films composed of well-ordered structures, millions of times smaller than a human hair. They then use specially prepared solutions of reagents in pressurized carbon dioxide gas to deposit the insulator in selected regions of the template. The polymer template is then removed, leaving behind a copy of the polymer’s structure in a rigid insulating material that can withstand the high temperatures and stress of electronic device fabrication. According to Watkins the key to this approach is the ability to reproduce the precise structure of the polymer template in another material. "It is relatively easy to produce intricate, highly-ordered structures out of a class of plastic materials called block copolymers, since the materials simply organize themselves into regular patterns. Our research allows us to transfer this structure to materials that are useful for the fabrication of cutting edge devices," Watkins says.

"This new technique gives semiconductor manufacturers a fast and effective way to move to the next generation of smaller devices," stated Watkins. In a paper released January 23, Watkins’ group and collaborators in the semiconductor industry report that structures made using this approach offer an excellent combination of electrical and mechanical properties. Engineers at Novellus Systems demonstrated that the films survive chemical mechanical planarization, a typical step in the manufacturing process and crucial test of the new material’s durability.

Watkins notes that additional work using this method is aimed at device applications such as sensing and detection, catalysis, separations, and photonics.

Plans for commercialization of the UMass technology are under way. Watkins says, "While the foundational technology was developed at UMass, we recognize the need to work with an array of industry partners to see this through to a commercial success. Our plans are to license the technology through a consortium for pre-competitive development. The member companies can then build their own positions around the process. Providing access to multiple partners is essential for broad acceptance."

Further work with the technique will be undertaken through MassNanoTech, a new center at the University of Massachusetts Amherst for nanoscale research, education, process prototyping and technology transfer. Watkins serves as co-director of the new center.

For further information on MassNanoTech, contact James Watkins, associate professor of chemical engineering, at 413/545-2569 or watkins@ecs.umass.edu.