As a Photonics Center Faculty member, Dal Negro and his group have access to the nanofabrication and processing facilities at both the Photonics Center and the Central Nanofabrication Facility at Boston University. The instruments available are summarized below:
A three RF targets sputtering system (Denton Discovery 18) is used for the deposition of light-emitting materials and nanostructures. This sputtering system allows both plasma reactive and direct sputtering of semiconductors and metal films.
Electron-Beam Writer for Nanolithography of plasmonics/photonics structures
Nanofabrication of photonics and plasmonic structures in carried out in Dal Negro group
At Photonics center using a Zeiss SUPRA 40VP SEM equipped with Raith Beam Blanker and a Nano Pattern Generation System (NPGS). The resolution of the electron beam at 30 kV is 1 nm, leading to a lateral resolution of 10 nm for imaging and writing. State of the art arrays of metal nanoparticles with 15nm interparticle spacing have been demonstrated by Dal Negro group using this equipment in the last three years.
Central Nanofabrication Facilities at Boston University
The nanofabrication facility houses extensive capabilities from scanning e-beam writers to various materials processing systems, allowing fabrication of complex nanostructures.
The nanofabrication facility spans an area of over 1500 sqft which has been remodeled to operate as a class-10,000 clean room. An isolated cleanroom inside the facility allows an even cleaner environment at the level of class 1000. A laminar-flow hood inside this clean room provides a volume of workspace with an environment down to class 100. A number of fume hoods and laminar-flow hoods provide localized clean space.
Substrate Preparation: Spin-Coating, Surface Profiling, and Optical Lithography
The clean-room facility includes spin-coater, surface profilometer, high-resolution optical microscopes, ozone stripper, plasma cleaner and mask aligner for substrate preparation for lithography. For insulating structures, a thin conducting layer is deposited for high resolution e-beam lithography on substrate surface.
Material Deposition: Evaporators and Sputtering Systems
The facility includes three thermal evaporators for dedicated nonmagnetic deposition, and multiple-material deposition. In addition, there is a sputtering system for deposition of materials such as niobium, oxides and nitrites. The supporting optical processing facility (OPF) in Photonics Center also houses a number of thermal evaporators, e-gun evaporators, and sputtering chambers.
Characterization includes check for structural integrity, surface topography and electrical continuity of electrical lines. Nanofabricated structures are characterized with the JEOL scanning electron microscope (SEM), a digital instruments atomic force microscope (AFM), and a probe station. Electrical characterization is also performed at low temperatures in 4-Kelvin dippers.
Wirebonding, 4-Point Probe Station, Pulse Probe
The facility includes a wedge bonder and a thermal ball bonder for making electrical contacts between the nanoscale structures and contact pads. In some cases, a four-point probe station with precision current sources and LCR meter allows room temperature measurement without bonding. An Agilent oscilloscope with capabilities for time-domain reflection characterization is used to check for electrical continuity with picosecond pulses.
Additional Fabrication Facilities
The central support facility for fabrication is the optical processing facility (OPF), which houses a number of optical mask aligners, reactive ion etch system, e-gun evaporators, thermal evaporators, sputtering chamber, plasma cleaners, probe station, and other materials processing and characterization systems.
Optical characterization Labs:
The Ultrafast Nanostructure Optics (UNO) Laboratory