Nanotechnology Advances Continue in Medicine, Computer Circuitry

With continuing miniaturization resulting from technological innovations, nanotechnology applications are expected to grow in a variety of areas, including computer logic and memory and medicine-delivery systems. This trend has created a need for an alternative technique for measuring computer circuits. To meet that need, scientists have found promise in a less-than-cutting-edge method: small-angle x-ray scattering.

Report Predicts Significant Growth in Nanoelectronic Logic and Memory

Nanoelectronic computer memory and logic products are expected to enter the market as early as this year. By 2008, $30 billion in nanoelectronic memory product sales are expected. By 2013, a market of $200 billion is possible, with another $20 billion in nanoelectronic logic products, according to a report by Business Communications Company. The report, RGB-286 Nanomaterials in Nanoelectronics, states that various nanomaterials, including carbon nanotubes, semiconductor nanowires, silicon nanocrystals or quantum dots, nanoscale magnetic films, and switchable molecular structures have emerged as candidates for next-generation memory and logic chips.

The need for nanomaterials in computer memory products arises from the continued miniaturization of devices and wiring on silicon wafers to meet the demand for increased processing power and memory density of computer chips. In the near future, carbon-nanotube-based memories processed by conventional deposition and patterning techniques and molecular electronic memories with microscale interconnects will emerge. In the longer term, those products will be replaced with ultrahigh-density molecular and solid-state memory arrays with nanowire interconnections, the report states.

Nanoelectronic logic technologies encompass new transistor materials and structures as well as novel logic architectures. Field-effect transistors with nanotube or nanowire conducting channels, as well as quantum-dot-based single electron transistors might provide a hybrid nano-microelectronic architecture. The use of nanomaterials as building blocks for new logic architectures that will combine new fabrication methods with ultrahigh device density, fault tolerance, and reprogrammability are seen as the ultimate outgrowth of this market.

Old X-Ray Technique Measures Nano-Sized Circuitry

An old x-ray technique may find new use in measuring dimensions of chip circuitry, according to the National Institute of Standards and Technology (NIST).

Computer chips are composed of millions of nanometer-scale devices. To measure those devices, the NIST-sponsored research found success with small-angle x-ray scattering (SAXS), a decades-old research tool used to study the structure of materials. Using the technique, the researchers characterized the size and shape of grid-like patterns with 180 nanometer line widths. With better than 1 nanometer precision, the team determined the average size of periodically repeating features arrayed in one- and two-dimensional patterns on three chemically different samples. Analyses of images captured with the x-ray technique found high-precision measurements of linewidths, spaces between line edges, and shapes of features. In addition, analyses yielded information on the roughness of walls and the edges of lines in the lattice-like pattern-features that arc key to quality control in the chip-making process.

The non-destructive SAXS technique is especially important as semiconductor processing and nanomanufacturing methods approach molecular and even atomic scales, according to NIST. Alternative measuring techniques, such as the use of scanning tunneling microscopes and related instruments, are unable to provide the same level of precision. The research was conducted by NlST in cooperation with Argonne National Laboratory's Advanced Photon Source, ExxonMobile Research Company, and the Shipley Company. The work was published in Applied Physics Letters.

Microneedles Promise Painless Medicine Delivery

Micrometer-scale needles could be used to deliver proteins, nanoparticles, and large and small molecules through human skin. Researchers at the Georgia Institute of Technology are investigating fabrication techniques for microneedles made from a variety of materials including metals, biodegradable polymers, silicon, and glass (Figure 1).

"Fabricating both hollow and solid microneedles in a variety of shapes, sizes, and materials allows us to deliver large molecules with significant therapeutic interest such as insulin, proteins produced by the biotechnology industry, and nanoparticles that could encapsulate a drug or demonstrate the ability to deliver a virus for vaccinations," said Mark Prausnitz, a professor in Georgia Tech's School of Chemical and Biomolecular Engineering and principal investigator for the project.

The microneedles range in size from 1 µm to 1,000 µm. Originally, researchers produced arrays of up to 400 needles designed to punch holes in the outer layer of skin to increase its permeability to small molecules. Those solid needles were made of silicon and manufactured using microlithography and etching technologies.