Damascene copper electroplating for on-chip interconnections, a process that we conceived and developed in the early 1990s, makes it possible to fill submicron trenches and vias with copper without creating a void or a seam and has thus proven superior to other technologies of copper deposition. We discuss here the relationship of additives in the plating bath to superfilling, the phenomenon that results in superconformal coverage, and we present a numerical model which accounts for the experimentally observed profile evolution of the plated metal.

Damascene copper electroplating for chip interconnections

Nanogels and microgels are soft, deformable, and penetrable objects with an internal gel-like structure that is swollen by the dispersing solvent. Their softness and the potential to respond to external stimuli like temperature, pressure, pH, ionic strength, and different analytes make them interesting as soft model systems in fundamental research as well as for a broad range of applications, in particular in the field of biological applications. Recent tremendous developments in their synthesis open access to systems with complex architectures and compositions allowing for tailoring microgels with specific properties. At the same time state-of-the-art theoretical and simulation approaches offer deeper understanding of the behavior and structure of nano- and microgels under external influences and confinement at interfaces or at high volume fractions. Developments in the experimental analysis of nano- and microgels have become particularly important for structural investigations covering a broad range of length scales relevant to the internal structure, the overall size and shape, and interparticle interactions in concentrated samples. Here we provide an overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels. The following aspects build the focus of our discussion: tailoring (multi)functionality through synthesis; the role in biological and biomedical applications; the structure and properties as a model system, e.g., for densely packed arrangements in bulk and at interfaces; as well as the theory and computer simulation.

Nanogels and Microgels: From Model Colloids to Applications, Recent Developments, and Future Trends

The robust, sensitive, and selective detection of targeted biomolecules in their native environment by prospective nanostructures holds much promise for real-time, accurate, and high throughput biosensing. However, in order to be competitive, current biosensor nanotechnologies need significant improvements, especially in specificity, integration, throughput rate, and long-term stability in complex bioenvironments. Advancing biosensing nanotechnologies in chemically “noisy” bioenvironments require careful engineering of nanoscale components that are highly sensitive, biorecognition ligands that are capable of exquisite selective binding, and seamless integration at a level current devices have yet to achieve. This review summarizes recent advances in the synthesis, assembly, and applications of nanoengineered reporting and transducing components critical for efficient biosensing. First, major classes of nanostructured components, both inorganic reporters and organic transducers, are discussed in the contex...

Synthesis, Assembly, and Applications of Hybrid Nanostructures for Biosensing

Life at Low Reynolds Number

Facile preparation of hydrogen-bonded supramolecular polyvinyl alcohol-glycerol gels with excellent thermoplasticity and mechanical properties

We use three-dimensional computer simulations to examine the free swimming of an elastic plate plunging sinusoidally in a viscous fluid with a Reynolds number of 250. We find that the free swimming velocity is maximized when the swimmer is driven near the first natural frequency leading to larger swimmer deformations, and that the free swimming velocity is nearly linearly related to the trailing edge displacement. The maximum swimmer performance is found at a non-resonance frequency. The maximum performance takes place when the swimmer exhibits a deformation pattern in which the transverse displacement of the swimmer's center of mass is minimized, which in turn reduces viscous losses.

Free swimming of an elastic plate plunging at low Reynolds number

Effect of aspect ratio in free-swimming plunging flexible plates

Using computational modeling, we design a microscopic swimmer made of a bilayered responsive hydrogel capable of swimming in a viscous fluid when actuated by a periodically applied stimulus. The gel has an X-shaped geometry and two bonded layers, one of which is responsive to environmental changes and the other which is passive. When the stimulus is turned on, the responsive layer swells and causes the swimmer to deform. We demonstrate that when such stimulus-induced deformations occur periodically the gel swimmer effectively propels forward through the fluid. We show that the swimming speed depends on the relative stiffness of the two gel layers composing the swimmer, and we determine the optimal stiffness ratio that maximizes the swimming speed.

Self-Propelled Microswimmer Actuated by Stimuli-Sensitive Bilayered Hydrogel

Mesoscale modelling of environmentally responsive hydrogels: emerging applications

An electrodeposition process for void-free bottom-up filling of sub-millimeter scale through silicon vias (TSVs) with Cu is detailed. The 600 μm deep and nominally 125 μm diameter metallized vias were filled with Cu in less than 7 hours under potentiostatic control. The electrolyte is comprised of 1.25 mol/L CuSO4 -0.25 mol/L CH3SO3H with polyether and halide additions that selectively suppress metal deposition on the free surface and side walls. A brief qualitative discussion of the procedures used to identify and optimize the bottom-up void-free feature filling is presented.

https://iopscience.iop.org/article/10.1149/2.0091901jes/pdf

Peter Yeh

Papers

Free swimming of an elastic plate plunging at low Reynolds number

Effect of aspect ratio in free-swimming plunging flexible plates

Self-Propelled Microswimmer Actuated by Stimuli-Sensitive Bilayered Hydrogel

Mesoscale modelling of environmentally responsive hydrogels: emerging applications

Bottom-Up Copper Filling of Large Scale Through Silicon Vias for MEMS Technology