21 research outputs found
Intrafield Distortion Characterization
Distortion of printed photoresist patterns exists in all photolithographic tools and can be generated by numerous factors. These noncorrectable overlay errors are the direct result of lens imperfections, machine inaccuracy, and reticle error. Any one of these factors can have extreme effects on pattern placement and quality. This study involved characterizing this anomaly and was the first of its kind at the Semiconductor & Microsystems Fabrication Laboratory (SMFL). Incorporating a unique test reticle, crosshairs were printed on silicon wafers. These features were measured via Manufacturing Electron Beam Exposure System (MEBES) market analysis to reveal any pattern migration. This analysis involves passing the electron stream over the beams of the crosshairs. The resulting signature from electron backscattering showed small movements of the pattern. Mathematical modeling of the raw data extracts correctable errors leaving a residual distortion map. These maps can be used as a figure of merit for the amount of pattern placement distortion within the photolithographic tool
A Pilot Study of Urokinase-Type Plasminogen Activator (uPA) Overexpression in the Brush Cytology of Patients with Malignant Pancreatic or Biliary Strictures
We have previously demonstrated that uPA is overexpressed in pancreatic tumors. In an attempt to diagnose these tumors earlier, we sought to determine whether uPA could be identified in endoscopic retrograde cholangiopancreatography obtained brushings in patients with malignant pancreatic and biliary strictures. Secondarily, uPA was measured in the serum of this patient population. uPA overexpression was identified in the cytologic tissue in 8 of 11 patients (72.7%). Serum analysis demonstrated a 2-fold higher concentration of uPA in the pancreaticobiliary cancer patients (1.27 versus 0.56 ng/mL; P = .0182). Also, uPA overexpression correlated with serum levels (P < .0001). This study confirms that uPA can be detected in the ERCP cytologically obtained tissue and is frequently present in a higher concentration in the serum of pancreaticobiliary cancer patients. A larger sample size will be required to address its value as a sensitive marker for the diagnosis of pancreatic or biliary cancers
Fabrication of Diamond Nanowires for Quantum Information Processing Applications
We present a design and a top-down fabrication method for realizing diamond
nanowires in both bulk single crystal and polycrystalline diamond. Numerical
modeling was used to study coupling between a Nitrogen Vacancy (NV) color
center and optical modes of a nanowire, and to find an optimal range of
nanowire diameters that allows for large collection efficiency of emitted
photons. Inductively coupled plasma (ICP) reactive ion etching (RIE) with
oxygen is used to fabricate the nanowires. Drop-casted nanoparticles (including
, and ) as well as electron
beam lithography defined spin-on glass and evaporated have been
used as an etch mask. We found nanoparticles to be the most
etch resistant. At the same time FOx e-beam resist (spin-on glass) proved to be
a suitable etch mask for fabrication of ordered arrays of diamond nanowires. We
were able to obtain nanowires with near vertical sidewalls in both
polycrystalline and single crystal diamond. The heights and diameters of the
polycrystalline nanowires presented in this paper are \unit[\approx1]{\mu m}
and \unit[120-340]{nm}, respectively, having a \unit[200]{nm/min} etch
rate. In the case of single crystal diamond (types Ib and IIa) nanowires the
height and diameter for different diamonds and masks shown in this paper were
\unit[1-2.4]{\mu m} and \unit[120-490]{nm} with etch rates between
\unit[190-240]{nm/min}.Comment: 11 pages, 26 figures, submitted to Diamond and related Materials;
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWV-4Y7MM1M-1&_user=10&_coverDate=01%2F25%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6dc58b30f4773a710c667306fc541cc
Chemical Mechanical Planarization for Ta-based Superconducting Quantum Devices
We report on the development of a chemical mechanical planarization (CMP)
process for thick damascene Ta structures with pattern feature sizes down to
100 nm. This CMP process is the core of the fabrication sequence for scalable
superconducting integrated circuits at 300 mm wafer scale. This work has
established the elements of the various CMP-related design rules that can be
followed by a designer for the layout of circuits that include Ta-based
coplanar waveguide resonators, capacitors, and interconnects for tantalum-based
qubits and single flux quantum (SFQ) circuits. The fabrication of these
structures utilizes 193 nm optical lithography, along with 300 mm process tools
for dielectric deposition, reactive ion etch, wet-clean, CMP and in-line
metrology, all tools typical for a 300 mm wafer CMOS foundry. Process
development was guided by measurements of physical and electrical
characteristics of the planarized structures. Physical characterization such as
atomic force microscopy across the 300 mm wafer surface showed local topography
was less than 5 nm. Electrical characterization confirmed low leakage at room
temperature, and less than 12% within wafer sheet resistance variation, for
damascene Ta line-widths ranging from 100 nm to 3 {\mu}m. Run-to-run
reproducibility was also evaluated. Effects of process integration choices
including deposited thickness of Ta are discussed.Comment: 31 pages, 16 figure
Engineering of Niobium Surfaces Through Accelerated Neutral Atom Beam Technology For Quantum Applications
A major roadblock to scalable quantum computing is phase decoherence and
energy relaxation caused by qubits interacting with defect-related two-level
systems (TLS). Native oxides present on the surfaces of superconducting metals
used in quantum devices are acknowledged to be a source of TLS that decrease
qubit coherence times. Reducing microwave loss by surface engineering (i.e.,
replacing uncontrolled native oxide of superconducting metals with a thin,
stable surface with predictable characteristics) can be a key enabler for
pushing performance forward with devices of higher quality factor. In this
work, we present a novel approach to replace the native oxide of niobium
(typically formed in an uncontrolled fashion when its pristine surface is
exposed to air) with an engineered oxide, using a room-temperature process that
leverages Accelerated Neutral Atom Beam (ANAB) technology at 300 mm wafer
scale. This ANAB beam is composed of a mixture of argon and oxygen, with
tunable energy per atom, which is rastered across the wafer surface. The
ANAB-engineered Nb-oxide thickness was found to vary from 2 nm to 6 nm
depending on ANAB process parameters. Modeling of variable-energy XPS data
confirm thickness and compositional control of the Nb surface oxide by the ANAB
process. These results correlate well with those from transmission electron
microscopy and X-ray reflectometry. Since ANAB is broadly applicable to
material surfaces, the present study indicates its promise for modification of
the surfaces of superconducting quantum circuits to achieve longer coherence
times.Comment: 22 pages, 7 figures, will be submitted to Superconductor Science and
Technology Special Focus Issue Journa
Conference of Microelectronics Research 2002
https://scholarworks.rit.edu/meec_archive/1011/thumbnail.jp