Ultraviolet Lithography

Ultraviolet lithography can produce lines for integrated circuits as small as 39 nm in one recent test. To help sustain Moore's law and cram more and more gates and memory units into a given space, manufacturers of microchips must make the lines in their circuitry ever smaller. This usually means working with a shorter-wavelength light beam for creating the patterns used for inscribing fine features on silicon or metal surfaces. The form of lithography currently in mass production now can produce a half-pitch size (equal lines and spaces in between) of 90 nm and isolated line widths of 65 nm. To produce a later generation after that you would need even shorter wavelengths.

At the Advanced Light Source at the Lawrence Berkeley National Lab (LBNL) a government-industry consortium of scientists is trying out this future lithography. Using a beam of synchrotron radiation in the extreme ultraviolet range they have produced 70-nm line/space intervals and isolated lines 39 nm wide (see figure). By the time this type of lithography comes into play, by about 2007, these numbers should be 45 and 25 nm, respectively. The consortium consists of a government side, the "Virtual National Lab" (LBNL, Livermore, and Sandia), and an industrial component comprising Intel, AMD, IBM, Infineon, Micron, and Motorola. (Naulleau et al., Journal of Vacuum Science Technology B, Nov/Dec 2002; contact Patrick Naulleau, pnaulleau@lbl.gov)