Wisconsin Alumni Research Foundation

Semiconductors & Integrated Circuits
Semiconductors Integrated Circuits
Enhanced Phase-Shifting Mask for Gate Widths and Vias
WARF: P01187US

Inventors: James Taylor, Lei Yang, Franco Cerrina

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a device that uses high-resolution lithography to fabricate nanoelectronic devices with gate widths down to 30 nm.
Lithographic processes are used to image features onto wafers, with the width of the features determining the speed of the chips. For example, Pentium 3 and Pentium 4 chips have nominal node sizes of approximately 180 nm and 120 nm, respectively.

Several factors limit the fabrication of smaller features, one of which is diffraction. Diffraction is an unwanted side effect of the lithographic process, which causes the feature produced on the chip to be larger than the feature on the mask. Several techniques have been employed to minimize the effects of diffraction, including PSMs (phase-shifting masks) that manipulate the phase difference to minimize diffraction. However, use of PSMs, as well as shorter wavelength X-rays, are limited to 1-D resolution enhancement.
The Invention
UW–Madison researchers have developed a clear, phase-shifting mask that can be used for 1-D features such as device gate widths and 2-D patterns such as contact holes (or vias). Specifically, the device positions two, adjacent, phase-shifting edges such that constructive interference occurs between the bright-peaks associated with the individual edges to minimize diffraction and enhance intensity.
  • Production of semiconductor computer chips
Key Benefits
  • Adapted to imaging both 1-D and 2-D patterns for low density microcircuits such as microprocessors
  • Produces printed wafer features that are five to six times smaller than mask features
  • Reduces constraints on the mask-to-wafer gap
  • Enhances intensity and requires less-sensitive positive resists
Additional Information
For current licensing status, please contact Jeanine Burmania at [javascript protected email address] or 608-960-9846