FAQ

 

What does SHARP do?

SHARP is a microscope that performs unique measurements in support of semiconductor manufacturing (i.e computer chip fabrication) research. Modern chipmaking uses an process called photolithography, which is akin to darkroom photography, and uses light to print circuit patterns onto wafers. Specifically, SHARP directs its attention to photomasks, which are 6-inch (150 mm) glass plates that carry the patterns for each single layer of a computer chip’s pattern. Those patterns are transferred onto a silicon wafer using light and incredibly high quality lenses that reduce the image 4x. When printing chips, even nanoscale defects (tiny bumps, pits, scratches or particles, 100 times smaller across than a red blood cell) can ruin a circuit. Since masks are expensive, defects have to be found and possibly fixed before they cause problems. SHARP can characterize defects with great detail. Unlike conventional microscopes, electron microscopes, and atomic-force microscopes (AFM), SHARP operates with extreme-ultraviolet (EUV) light, near 13.5-nm wavelength, the same color of light used in next-generation chip-making tools. It is amusing to note that the size and shape of defects that can cause major problems in circuit printing are proportionally equivalent to a few errant tortillas tossed onto an area the size of California. Many real-world defects are flat and wide like that.

 

Who built SHARP?

SHARP was created by a team of scientists, engineers, and technicians at Lawrence Berkeley National Laboratory’s (LBNL) Center for X-Ray Optics (CXRO) for a semiconductor industry research consortium called SEMATECH. The team leader and principal investigator at LBNL is Kenneth A. Goldberg, a 20-year veteran of EUV, short-wavelength optics, and synchrotron research. Major components of SHARP’s experimental system were fabricated and assembled by
ADC, Inc. The optics and coatings were developed in-house, with special components coming from Tinsley, Mirrorcle Technologies, Inc., Gooch and Housego, OptoDiode (IRD), PI MiCos, GALIL, WAGO, and many others.
 

Who uses SHARP?

SHARP’s users mainly come from the major semiconductor manufacturing companies. This includes IBM, Intel, GlobalFoundries, Samsung, TSMC, SEMATECH, and others. Students and postdoctoral fellows from The University of California at Berkeley and fellow researchers from LBNL use sharp for advanced microscopy and imaging research.
 

Why is SHARP important?

In science and engineering, progress requires data from careful experimentation, with high-quality feedback. SHARP gives today’s EUV lithography researchers a window into the future of chipmaking, 2, 5, or 10 years out. At this time, there are no commercial microscopes that can perform the kinds of measurements that SHARP makes possible. SHARP’s Fourier synthesis illuminator enables it to emulate the illumination partial coherence properties of current and future lithography and mask-imaging tools.
 

Are there any publications on SHARP?

Yes. This page has an up-to-date publication List.
 

Are there any SHARP presentations available for download?

Yes. This page has links to some recent presentations on SHARP.
 

What wavelength/color of light does SHARP use?

SHARP is designed for use in a narrow, tunable range near 13.5-nm wavelength. Light in this part of the spectrum is called extreme ultraviolet (EUV)—or vacuum ultraviolet, because it doesn’t propagate in air. You can’t see it with your eyes, but it interacts strongly with all materials, and SHARP has various cameras and sensors that can detect it. Specialized optical elements like mirrors are made with customized multilayer-coatings that reflect EUV light. The lenses we use operate by diffraction, holographically, rather than by refraction, like a conventional glass lens.
 

What kind of lenses does SHARP use?

SHARP uses Fresnel zoneplate lenses created by electron-beam lithography. The lenses are just 100 μm wide, the width of a single hair. Light passes through a hole in a tiny membrane to illuminate the surface of the mask in a small area. The reflected light is directed into the tiny lens and projected upward to an EUV-sensitive CCD camera. For the various lenses we use in SHARP, the zoneplate focal lengths vary from 1.5 mm down to 275 μm, very close to the mask surface, but not touching. You can learn more about zoneplate lenses at zoneplate.lbl.gov.
 

What is SHARP’s imaging resolution?

SHARP is built with lenses and illumination that can reach 26-nm half-pitch resolution on the mask surface. The theoretical limit of modulation down to 22-nm has been observed with extreme illumination conditions. Higher resolutions may be possible in the future. As of September 2015, we have measured lines down to 22-nm half-pitch on the mask—resolution-testing results will be reported at an upcoming conference.
 

What kinds of illumination can SHARP deliver?

SHARP has a highly customizable Fourier-synthesis illuminator that can control the angular profile of the illumination in a lossless manner. SHARP can deliver highly coherent light (below 0.1 σ), with a range of off-axis incidence angles from 2–19°; and it can create arbitrary illumination partial coherence, with disk, annular, monopole, dipole, quadrupole, and quasar illumination, with σ values from 0–1 for many NA values. Angular control is continuous or discrete. Please tell us what you need, and we can probably do it.
 

How much of the mask surface can SHARP measure?

SHARP’s mask stage can reach all points on the mask surface with both EUV and the visible light microscope. Within a single EUV image, SHARP’s field of view varies with the zoneplate lens we are using, but is typically about 30 μm. Within that field of view, there is a sweet spot where the aberrations are minimized, and diffraction-limited quality can be expected. The sweet spot size is typically a few μm diameter.
 

What are the mask shipping instructions?

Mask shipping instructions are provided here.
 

How can I contact the SHARP team?

Contact information is provided here.
 

How fast is SHARP?

SHARP’s single-image exposure time is typically 5-8 seconds in the high-quality exposure mode. Shorter exposure times are used for navigation and alignment. Users typically record 11 to 21 steps through focus, with 0.4 μm step size, or larger. Depending on the experiment plan, SHARP can record approximately 8 series per hour.
 

Can SHARP measure the reflectivity of an EUV mask?

SHARP has calibrated photodiodes for measuring the incident and mask-reflected photon flux. We are still calibrating the tool, but we expect such measurements to become commonplace soon.
 

What can I do to prepare my experiments for SHARP?

We recommend that you involve the LBNL team in the early planning stages of your experiments, wherever possible. We are happy to make recommendations that could lead to improved outcomes for your experiments. For specific information about conducting successful experiments on SHARP, we have created an SHARP_Experiment_Preparation2013-08-05. Please go through it, and direct any remaining questions to Kenneth Goldberg, KAGoldberg (at) lbl.gov. This page also describes aspects of experiment plan creation.
 

How can members of my organization become SHARP users?

Please contact Kenneth Goldberg for more information, KAGoldberg (at) lbl.gov