Use Of Plasma Etching Research Articles

Superhydrophobic polymeric films with hierarchical structures produced by nanoimprint (NIL) and plasma roughening

The structuration of various polymeric films has been studied to create superhydrophobic surfaces. Nanoimprint lithography and/or plasma etching processes with CF4/Ar have been used on FEP, PMMA and PET polymer films. On the one hand, the effect of the CF4/Ar gases, the input power and the plasma treatment duration have been investigated in terms of etching and fluorination degree, and XPS analyses are precisely discussed. On the other hand, wettability performances were characterized. Relationships between the contact angle, the contact angle hysteresis and the surface structures have been investigated. The wetting behaviors and the transition between the Wenzel and the Cassie-Baxter states was discussed as a function of the roughness. We have prepared each studied polymer films in transparent and flexible superhydrophobic surfaces whose contact angle are ∼160° and hysteresis are ∼2°. A short plasma treatment time (10 s) is sufficient to obtain a superhydrophobic behavior on FEP and PMMA. Results indicate that hierarchical structures allow a more stable superhydrophobic state regarding inhomogeneities. Moreover, the use of plasma etching is suggested to overcome some limitations of the NIL in the case of structures with a high aspect ratio. Finally, a quick and large surface fabrication method for superhydrophobic films is detailed.

Via-First Process to Enable Copper Metallization of Glass Interposers With High-Aspect-Ratio, Fine-Pitch Through-Package-Vias

A via-first process for metallizing copper on glass substrates is presented using a thin, patternable polymer film, electroless copper deposition, and semiadditive processing. A procedure for partially precuring the polymer was developed in order to achieve a tented via structure after dry-film lamination and curing. The flexibility of the process is demonstrated by the use of plasma etching, CO2, and UV laser ablation as patterning technologies. Metallization by electroless copper deposition and semiadditive processing is shown to be conformal, continuous, and without defects on the surface and in the vias as demonstrated by cross-sectional analysis. Glass of $100~\mu \text{m}$ thickness with vias of 10– $20~\mu \text{m}$ diameter and $40~\mu \text{m}$ pitch was metallized to demonstrate the dimensional capability of the process. Thermomechanical reliability was validated by copper peel testing after highly accelerated stress testing and daisy-chain resistance measurements taken throughout thermal cycle testing.

Plasma etching to enhance the surface insulating stability of alumina for fusion applications

A significant increase in the surface electrical conductivity of alumina, considered one of the most promising insulating materials for numerous applications in fusion devices, has been observed during ion bombardment in vacuum due to oxygen loss by preferential sputtering. Although this is expected to cause serious limitations to insulating components functionality, recent studies showed it is possible to restore the damaged lattice by oxygen reincorporation during thermal treatments in air. These studies also revealed a correlation between conductivity and ion beam induced luminescence, which is being used to monitor surface electrical conductivity degradation and help qualify the post irradiation recovery. Work now carried out for Wesgo alumina considers oxygen implantation and plasma etching as additional methods to improve recovered layer depth and quality. Both conductivity and luminescence results indicate the potential use of plasma etching not only for damage recovery, but also as a pre-treatment to enhance material stability during irradiation.

Roughening of Polyimide Surface for Inkjet Printing by Plasma Etching Using the Polyimide Masked with Polystyrene Nanosphere Array.

Two key conditions are required for the application of fine-line inkjet printing onto a flexible substrate such as polyimide (PI): linewidth control during the inkjetting process, and a strong adhesion of the polyimide surface to the ink after the ink solidifies. In this study, the properties of a polyimide surface that was roughened through etching in a He/SF6 plasma, using a polystyrene nanosphere array as the etch mask, were investigated. The near-atmospheric-pressure plasma system of the He/SF6 plasma that was used exhibits two notable properties in this context: similar to an atmospheric-pressure plasma system, it can easily handle inline substrate processing; and, similar to a vacuum system, it can control the process gas environment. Through the use of plasma etching, the polyimide surface masked the 120-nm-diameter polystyrene nanospheres, thereby forming a roughened nanoscale polyimide surface. This surface exhibited not only a greater hydrophobicity--with a contact angle of about 150° for water and about 30° for silver ink, indicating better silver linewidth control during the silver inkjetting process--but also a stronger adhesion to the silver ink sprayed onto it when compared with the flat polyimide surface.

Ordered surface structures from PNIPAM-based loosely packed microgel particles

On-surface self-assembly of several types of microgels prepared via the precipitation polymerization of (N-isopropylacrylamide) (NIPAM) with N,N′-methylenebisacrylamide (MBA), acrylic acid or acrylamide as comonomers is investigated with the aim to establish the main factors that govern the formation of periodic loosely packed (PLP) two-dimensional arrays. A core–shell structure is detected for all microgels, with the thickest shells being observed for the microgels containing acrylic acid or acrylamide. The main factor driving the formation of PLP arrays and determining the microgel separation is found to be the presence of large low-density shells around the highly cross-linked cores of the microgels. This key observation of our experiments has been explained by the developed theoretical model that proves to adequately describe the experimental findings. The size of microgel dry-state “footprints” can be reduced by making use of plasma-etching. The periodic microgel arrays are used as masks for the preparation of patterns of reactive silanes with controllable separation between the patterned features. Sputtering of gold onto the periodic microgel arrays followed by washing out the microgels in ultrasonic bath is proven to be an efficient way of preparing perforated gold films with PLP holes.

Nanostructured biointerfaces

Colloidal lithography is used to create nanostructured interfaces suitable for studying and interacting with cellular biosystems. Large areas of patterned surface can be produced. We investigate the use of plasma etching for transfer of the pattern of individual colloidal particles into the substrates to create short-range ordered arrays of topographic and/or chemical nanostructures. Colloidal masks perform differently to traditional photoresist masks and local redeposition of material around the particle has significant impact on the resultant structures. The colloidal particles can be reshaped to allow the fabrication of flat-topped structures. Topographic and chemical nanostructures can be used to template the self assembly of macromolecules. The phase separation of thin films of PS-PMMA symmetric block copolymers above nanostructure sites is aligned at the surface nanostructure by topographic features. PLL-PEG assembly at alkanethiol-modified nanoscale chemical patterns of gold/silicon allows the production of nanoscale protein patterns. Patterns of ferritin 100 nm in diameter are demonstrated.

Understanding the architecture of the egg shell

The biological function of the egg shell is as a chamber for embryonic development and from which the chick is able to emerge at the appropriate time. The characteristics which serve this purpose in an optimum way are quite different from the requirements of the table egg industry. Among the challenges imposed by commercial egg production and marketing is the ability to resist fracture damage. The industry sustains economic loss from cracked eggs and at least some of the cracking can be attributed to deficiencies in shell structure. While early research concentrated on the thickness of the shell, more recently there has been an increased emphasis on its fine structure and shape. Egg shell strength has been the subject of much research, but relatively little attention has been paid to the relationship of strength and other shell parameters to breakage under commercial conditions. Where this has been studied, the power of shell measurements to predict breakage has been found to be low. The ultrastructure of the shell has been studied during the past 25 years and this has led to extensive gains in understanding. In the case of the mammillary layer, knowledge has been advanced following the use of plasma etching and scanning electron microscopy. Several structural anomalies have been described which significantly affect shell strength and resistance to breakage. The use of finite element analysis has made possible a definitive description of shell shape and led in turn to useful work on crack generation and shell failure. Studies of the protein content of the shell, which may be an important factor in its crystal growth and structure, are also contributing to our understanding of egg shell architecture.

Plasma Etching of PLT Thin Films and Bulk PLZT Using Fluorine- and Chlorine-Based Gases

ABSTRACTPotential applications for ferroelectric thin films include both electronic and optoelectronic devices. In order to integrate a large number of devices on a single ceramic film or to incorporate ceramic devices with silicon-based integrated circuits, suitable film patterning techniques must be developed. In this study, the use of plasma etching for device patterning of PLT thin films has been explored using a dc hollow cathode discharge with HCl and CF4 etching gases. At room temperature, no etching of material is discernable. As the substrate temperature is increased, however, relatively rapid etching takes place. Etch rates for PLT thin films as high as 6500 Å/hour were measured. Etching occurred in both chlorinated and fluorinated plasmas, but at considerably different rates. The etch rate is enhanced by a factor of six by using a combination of HCl and CF4 in the plasma. After etching, the stoichiometry of the film, measured by energy dispersive spectroscopy (EDS), varied greatly with changes in substrate temperature. Although the removal rate for each element is different, all traces of lead, titanium, and lanthanum can be removed from the substrate over a wide range of plasma etching conditions.

FMRFamide‐like immunoreactivity within the nervous system of the nematodes Panagrellus redivius, Caenorhabditis elegans and Heterodera glycines

A polyclonal antiserum raised against the molluscan neuromodulatory peptide Phe‐Met‐Arg‐Phe‐amide (FMRFamide) reacts with nervous tissue in the free‐living nematodes Panagrellus redivius and Caenorhabditis elegans and in infective juveniles (J2) of the soybean cyst nematode Heterodera glycines. Sectioning of the nematodes was unnecessary but penetration of the antibody was improved by cutting the animals or by use of plasma etching to breach the cuticle before incubation in antiserum. Both procedures required subsequent exposure to detergents or partial digestion with protease K for optimum immunoreactivity. A positive reaction was observed for all three nematodes in the longitudinal nerve cords, nerve ring and ventral and lateral ganglia. Neurones were also visualized in association with the vulva in the free‐living species and the spicules of male P. redivius. In H. glycines, neurones innervating the pharynx reacted positively, as did two loops of neural tissue on either side of the ventral nerve cord slightly anterior to the anus. Immunoreactivity was also noted in the amphidial pouches of H. glycines after prolonged (15 min) protease treatment. Further work is needed to establish the structure of the peptide antigen localized in these nematodes.