83 research outputs found
Enhanced Adhesion Between Electroless Copper and Advanced Substrates
In this work, adhesion between electrolessly deposited copper and dielectric materials for use in microelectronic devices is investigated. The microelectronics industry requires continuous advances due to ever-evolving technology and the corresponding need for higher density substrates with smaller features. At the same time, adhesion must be maintained in order to preserve package reliability and mechanical performance. In order to meet these requirements two approaches were taken: smoothing the surface of traditional epoxy dielectric materials while maintaining adhesion, and increasing adhesion on advanced dielectric materials through chemical bonding and mechanical anchoring.
It was found that NH3 plasma treatments can be effective for increasing both catalyst adsorption and adhesion across a range of materials. This adhesion is achieved through increased nitrogen content on the polymer surface, specifically N=C. This nitrogen interacts with the palladium catalyst particles to form chemical anchors between the polymer surface and the electroless copper layer without the need for roughness. Chemical bonding alone, however, did not enable sufficient adhesion but needed to be supplemented with mechanical anchoring. Traditional epoxy materials were treated with a swell and etch process to roughen the surface and create mechanical anchoring. This same process was found to be ineffective when used on advanced dielectric materials. In order to create controlled roughness on these surfaces a novel method was developed that utilized blends of traditional epoxy with the advanced materials. Finally, combined treatments of surface roughening followed by plasma treatments were utilized to create optimum interfaces between traditional or advanced dielectric materials and electroless copper. In these systems adhesion was measured over 0.5 N/mm with root-mean-square surface roughness as low as 15 nm. In addition, the individual contributions of chemical bonding and mechanical anchoring were identified.
The plasma treatment conditions used in these experiments contributed up to 0.25 N/mm to adhesion through purely chemical bonding with minimal roughness generation. Mechanical anchoring accounted for the remainder of adhesion, 0.2-0.8 N/mm depending on the level of roughness created on the surface. Thus, optimized surfaces with very low surface roughness and adequate adhesion were achieved by sequential combination of roughness formation and chemical modifications.Ph.D.Committee Chair: Kohl, Paul; Committee Co-Chair: Bidstrup Allen, Sue Ann; Committee Member: Hess, Dennis; Committee Member: Nair, Sankar; Committee Member: Qu, Jianmi
Multi-scale Optics for Enhanced Light Collection from a Point Source
High efficiency collection of photons emitted by a point source over a wide
field-of-view (FoV) is crucial for many applications. Multi-scale optics over
improved light collection by utilizing small optical components placed close to
the optical source, while maintaining a wide FoV provided by conventional
imaging optics. In this work, we demonstrate collection efficiency of 26% of
photons emitted by a point-like source using a micromirror fabricated in
silicon with no significant decrease in collection efficiency over a 10 mm
object space.Comment: 4 pages, 4 figure
Low SWAP Laminated Electrostatic Analyzers for CubeSat Applications
Instead of a cylindrical or spherical tophat design, these analyzers use flat plate with thousands of individual apertures. This flat plate geometry greatly eases manufacturing, and results in a very inexpensive instrument as describe by Enloe et al. (2003)
Spatially uniform single-qubit gate operations with near-field microwaves and composite pulse compensation
We present a microfabricated surface-electrode ion trap with a pair of
integrated waveguides that generate a standing microwave field resonant with
the 171Yb+ hyperfine qubit. The waveguides are engineered to position the wave
antinode near the center of the trap, resulting in maximum field amplitude and
uniformity along the trap axis. By calibrating the relative amplitudes and
phases of the waveguide currents, we can control the polarization of the
microwave field to reduce off-resonant coupling to undesired Zeeman sublevels.
We demonstrate single-qubit pi-rotations as fast as 1 us with less than 6 %
variation in Rabi frequency over an 800 um microwave interaction region. Fully
compensating pulse sequences further improve the uniformity of X-gates across
this interaction region.Comment: 14 pages, 8 figure
Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation
Recent advances in quantum information processing with trapped ions have
demonstrated the need for new ion trap architectures capable of holding and
manipulating chains of many (>10) ions. Here we present the design and detailed
characterization of a new linear trap, microfabricated with scalable
complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited
to this challenge. Forty-four individually controlled DC electrodes provide the
many degrees of freedom required to construct anharmonic potential wells,
shuttle ions, merge and split ion chains, precisely tune secular mode
frequencies, and adjust the orientation of trap axes. Microfabricated
capacitors on DC electrodes suppress radio-frequency pickup and excess
micromotion, while a top-level ground layer simplifies modeling of electric
fields and protects trap structures underneath. A localized aperture in the
substrate provides access to the trapping region from an oven below, permitting
deterministic loading of particular isotopic/elemental sequences via
species-selective photoionization. The shapes of the aperture and
radio-frequency electrodes are optimized to minimize perturbation of the
trapping pseudopotential. Laboratory experiments verify simulated potentials
and characterize trapping lifetimes, stray electric fields, and ion heating
rates, while measurement and cancellation of spatially-varying stray electric
fields permits the formation of nearly-equally spaced ion chains.Comment: 17 pages (including references), 7 figure
Demonstration of integrated microscale optics in surface-electrode ion traps
In ion trap quantum information processing, efficient fluorescence collection
is critical for fast, high-fidelity qubit detection and ion-photon
entanglement. The expected size of future many-ion processors require scalable
light collection systems. We report on the development and testing of a
microfabricated surface-electrode ion trap with an integrated high numerical
aperture (NA) micromirror for fluorescence collection. When coupled to a low NA
lens, the optical system is inherently scalable to large arrays of mirrors in a
single device. We demonstrate stable trapping and transport of 40Ca+ ions over
a 0.63 NA micromirror and observe a factor of 1.9 enhancement in photon
collection compared to the planar region of the trap.Comment: 15 pages, 8 figure
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