The Cornell NanoScale Science & Technology Facility (CNF)
The Unaxis SLR 770 Etcher (pictured left) cuts deep patterns into single crystal silicon substrates. The resulting features are used for microelectromechanical systems (MEMS) and biological applications. Etch rates up to two micrometer per minute and aspect ratios of 20:1 can be obtained using photoresist or silicon dioxide as a masking medium.
Aloysha Molnar’s research group, Electrical and Computer Engineering, used the Unaxis SLR 770 to create packaging for integrated circuits with three-dimensional time-resolved imaging capabilities. These circuits image microorganisms and other biological samples with this proper packaging. A portable, flat, easily manufactured package enables the user to place biological samples on slides directly above the imaging chip. The chip was developed using laser cutting, photolithography, epoxies, and metal deposition. At CNF, aligning and adhering the chip to a holder wafer finalized the packaging procedure. The research benefits imaging technologies for microorganisms.
The ASML 300C DUV Stepper (inset) is a photolithography instrument used at CNF. It is a projection printer that uses deep ultraviolet lens columns to provide a 4:1 reduction with a variable field size up to a 21-millimeter square. The minimum feature size is less than 20 micrometers. Wafer sizes of up to 200 millimeters can be accommodated, as well as smaller pieces.
John Marohn's research group, Chemistry and Chemical Biology, used the ASML Stepper for researching micron-scale waveguides to enable nanoscale magnetic resonance imaging. The left image pictured is a fabricated coplanar waveguide. The grid lines above and below the centerline are used to optically locate the center. The research has implications for biomolecular imaging.
The Veeco Icon atomic force microscope for high-resolution profilometry is used to scan a surface with a sharp tip at the free end of a microfabricated cantilever beam. The apex of the tip either gently or intermittently touches the sample during contact or tapping mode imaging. The ultra small repulsive or attractive forces existing between the tip and the sample cause the cantilever to move up and down vertically to the surface. During this scanning process, bending deflection, oscillation, and torsion of the cantilever can be simultaneously measured.
Huili Grace Xing's research group, Electrical and Computer Engineering, used the Veeco Icon to experiment on Van der Waals (vdW) solids. Xing’s research at CNF demonstrates an important building block in vdW solids—room temperature Esaki tunnel diodes. The upper left photo is an optical image of fabricated devices on silicon-oxygen/silicon substrates created by the Veeco Icon. The research will enable the use of Van der Waals solids for powering a range of electronic and photonic applications.
This is an ABM contact aligner. The AMB high-resolution mask aligner is a photolithography instrument. It is a very versatile instrument with interchangeable light sources that allow Near-UV and Mid- and Deep-UV exposures in proximity or contact modes.
Paul L. McEuen's research group, Applied and Engineering Physics, used the ABM contact aligner to create micro-tweezers in order to freely manipulate carbon nanotubes and graphene. The microtweezer tips are made from the element gold, and covered by gold dendrites, which stick to the supportive, semi-flexible frame of photoresist. The microtweezers have enabled measurements important to solving the major puzzle of understanding carbon nanotubes unique vibrational properties.
The Zeiss Ultra 55, pictured left, is a scanning electron microscope (SEM) optimized for high-resolution imaging. It is capable of operating beam energies from 100 volts to 30 kilovolts. It maximizes imaging resolution at low beam energies and is equipped with a backscatter electron detector engineered to image electrons with energies less than two kiloelectron volts. An energy filter incorporated into the detector enables energy selective backscatter (ESB) imaging. This signal can be used to obtain contrast between regions of different composition.
Roman Akhmechet, Phoebus Optoeletronics, LLC, used the Zeiss Ultra 55 SEM to complete two projects: the optical component fabrication of a biosensor based on surface plasmon resonances and the development of an on-chip pixelated polarmeter device. These metasurface structures simultaneously deliver higher transmittance and lower cross talk between pixels than the current generation of wire-grid-based pixelated polarmeters.
The Anneal 1 Furnace is an atmospheric furnace with a 42-inch flat zone capable of processing up to six-inch diameter wafers. The furnace tube is equipped with nitrogen gas for inert ambient processing, hydrogen gas for forming gas mixtures with nitrogn, and oxygen for dry oxidation with or without hydrogen chloride.
The CNF has 20 furnace tubes for growing silicon oxide and depositing polysilicon, silicon nitride, and silicon oxide, as well as supporting processes for microelectromechanical systems and cleaning wafers before deposition.
The Oxford Cobra Inductively Coupled Plasma (ICP) Etcher is configured for state of the art nanoscale etching. The system includes a wide range temperature electrode (-150° to 400°C), which enhances the spectrum of materials that can be etched with volatile chemistries. The etcher is equipped to use nine gas chemistries: hydrogen bromide, chlorine, boron trichloride, sulfur hexafluoride, oxygen, hydrogen, argon, and methanol. This system expands CNF’s etching capabilities significantly, offering advanced silicon photonics, magnetic based materials, cryogenic silicon etch, single crystal and nanocrystalline diamond, and silicon carbide. The etcher allows for highly uniform etching over a 200mm-sized area, and it is equipped with an optical emission spectroscopy, which allows researchers to monitor chamber conditions and the end product.
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The CNF Short Course, Technology and Characterization at the Nanoscale (CNF TCN), is a three and half day intensive course, held in January and June. The short course combines lectures and laboratory demonstrations to impart a broad understanding of the science and technology required to undertake research in nanoscience. The course is an ideal way for faculty, graduate students, postdocs, and staff members to quickly become fully informed about the technologies that CNF researchers use. Potential CNF facility users should attend the course, which is open to the general public. The class size is limited due to the course’s hands-on components.
Introducing the nanoworld to young minds produces some of the best days at CNF. Although CNF cannot take middle and high school groups into the cleanroom, CNF staff takes a great deal of hands-on experimentation to them. CNF also publishes a newsletter, Nanooze, designed specifically to engage young people in the sciences. The CNF Research Experience for Undergraduates (REU), a summer internship program, brings five or more undergraduate students from across the nation to work on a well-defined and independent 10-week research project.
The Oxford 81 Etcher is an 8-inch diameter parallel plate, turbo-pumped reactive ion etch system dedicated to processes involving fluorine-based gas chemistries such as fluoroform, Tetrafluoromethane, and Sulfur hexafluoride. Processes are available for anisotropically etching silicon dioxide, silicon nitride, and silicon. Other gases available are argon and oxygen.
Daniel C. Ralph's research group, Physics, used the Oxford 81 Etcher to fabricate ferromagnetic wires with perpendicular anisotropy for graphene spinvalve devices. The wires are formed via sputter deposition on pre-defined silicon nitride beams on a silicon substrate. A dry transfer technique is used to place a graphene flake onto the wires. The fabrication method minimizes or eliminates the exposure of the metal to oxygen, resist residues, and heat that would degrade the quality of the resulting device. An image of the completed device is shown in the left photo. Research on graphene spinvalve devices has implications of the electronics industry.
The Cornell NanoScale Science and Technology Facility (CNF) is a national user-facility that, since 1977, has provided state-of-the-art nanofabrication resources—high tech equipment and expert staff support—to the national science community. Research at CNF encompasses physical sciences, engineering, and life sciences with a strong interdisciplinary emphasis. Users from academia, industry, and government laboratories learn to use the facility’s tools and instrumentation in order to accomplish their research projects.
CNF’s research equipment includes a tool set worth $160 million. The CNF scientific and technical staff offers expertise in physics, materials science, electrical and chemical engineering, and biology. This staff, together with the administrative staff, provides training, on-site user support, process support, and advice.
Researchers, representing over 800 projects, use the fabrication, synthesis, characterization, and integration resources at the CNF to build structures, devices, and systems from atomic to complex length-scales.