Nano-imprint lithography (NIL), a polymer stamping process, looms as the next revolutionary way to get past the limitations of conventional photolithography. Although this technology is still in its infancy, promising laboratory developments have emerged for creating NIL devices (see the table).
The technology allows the low-cost creation of chips with feature sizes ranging from 20 to 100 nm on 4-in. silicon wafers. It also can make structures with high aspect ratios ranging from 1 to 80, which is beneficial for microfluidics, micro-optics, and other nanostructures.
NIL is part of a number of micro and nano patterning technologies that include hot embossing, ultraviolet (UV) embossing, and injection molding. The technology promises devices at one-tenth the cost of photolithography, but it still requires the development of production-ready tools and a manufacturing infrastructure.
The technology must develop higher-quality molds or templates, more precise alignment tools, and greater chip-defect control to be more successful. Many traditional semiconductor vendors are still skeptical about NIL's future, viewing it as an immature technology that may never fly. But don't tell that to its proponents.
Stan Williams, senior fellow and director of quantum research at Hewlett-Packard's laboratories, routinely makes experimental devices with 30-nm feature sizes using NIL, and HP isn't alone. EV Group, Molecular Imprints, Nanonex, Obducat, and Suss MicroTec are also involved with NIL technology. In fact, EV Group recently organized the NIL.com Consortium to push for the commercialization of NIL technology. The consortium includes universities, research institutes, and commercial companies.
The technology's importance can be seen from the fact that it's mentioned in the International Technology Roadmap for Semiconductors (ITRS). This joint planning report from the chip industry details technologies likely to become winners in chip manufacturing.
For cost-effective NIL, Jun-ho Jeong of the Korea Institute of Machinery and Materials proposes a UV-based NIL approach in which an element-wise patterned stamp (EPS) is used in low-vacuum or atmospheric environments (see the figure). He believes that this approach has two major advantages over other lithographic techniques: low cost and high resolution.
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