AIT Highlights
AIT Highlights

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a worldwide unique, high-resolution, extreme-ultraviolet (EUV) Fresnel zoneplate microscope, dedicated to photomask research. The AIT is run by Lawrence Berkeley National Laboratory's (LBNL) Center for X-Ray Optics (CXRO) for SEMATECH and it's member companies.

Background. EUV Lithography (EUVL) is a so-called "next generation lithography" (NGL) technique that uses short-wavelength (13 nm) EUV light to mass-produce tiny (45-nm, 32-nm, 22-nm and below) integrated circuit patterns. In EUVL, light shines on a patterned, reflective mirror, called a "mask", a "reticle", or a "photomask." EUV projection lenses focus the mask's reflected light onto a silicon wafer coated with a thin, light-sensitive "photoresist" film, thus transferring the pattern, and creating one layer of a microchip, with nanometer scale features.

The AIT. Using a single holographic zoneplate lens, floating 1 mm above the mask surface, the AIT captures the aerial image reflected from a mask, and projects it with 1000× magnification directly onto an EUV-light-sensitive CCD camera. The continuous-tone images reveal subtle features in the image intensity without the limitations of printing into photoresist. With five different zoneplate lenses to choose from, the AIT can emulate the spatial resolution of current and future EUV projection lithography tools.

AIT Description

How it works.

Monochromatic EUV light from a bending magnet beamline at Lawrence Berkeley National Laboratory's Advanced Light Source illuminates a 30-micron region of the mask surface at 6° incidence. One of the five zoneplate lenses is positioned into the reflected beam and projects a highly magnified image of the mask surface onto an EUV-sensitive CCD camera approximately 1 meter away. A 45° turning mirror bends the beam horizontally toward the CCD, away from the illuminating optics.

The AIT is used in all areas of EUV mask research: measuring amplitude and phase defects on patterned and blank masks, line-edge roughness, defect-repair evaluation, optical proximity correction, multilayer phase roughness, mask architecture, the effects of mask contamination, and more.

Our Team. SEMATECH, an international consortium that includes the world's largest semiconductor manufacturers, sponsors the AIT's research at Lawrence Berkeley National Laboratory. A team of scientists and engineers, led by Kenneth Goldberg operates the AIT, serving SEMATECH's member companies, and the EUV lithography community. The LBNL team members are project scientist, Iacopo Mochi; chief engineer, Senajith Rekawa; postdoctoral researcher, Markus Benk; engineering associate, Nathan Smith; graduate student research associate, James Macdougall; research assistant, Elizabeth Martin; and many other collaborators from within The Center for X-Ray Optics (CXRO). The AIT's SEMATECH project managers are C.C. Lin, and Andy Ma.

The AIT Team has recently designed a new, radically efficient, EUV Actinic Mask Imaging Microscope, for EUV masks generations out to 8 nm. They call it the "SHARP Microscope": The SEMATECH Actinic Reticle Review Project. Synergistic with the MET5, SHARP will reach and surpass a 0.5 wafer-side numerical aperture (NA) value on day one of operations, bringing 2025 mask development to 2011. The SHARP project is now underway, and the tool will come online in late 2012.