SkinLink: On-body Construction and Prototyping of Reconfigurable Epidermal Interfaces

Influence of surface pre-treatment with mechanical polishing, chemical, electrochemical and ion sputter etching on the surface properties, corrosion resistance and MG-63 cell colonization of commercially pure titanium.

Physical and chemical etching in plasmas

Surface pre-treatments of Ti-Nb-Zr-Ta beta titanium alloy: The effect of chemical, electrochemical and ion sputter etching on morphology, residual stress, corrosion stability and the MG-63 cell response

Microarrays of n-GaAs were fabricated for both (100) and (111) by colloidal crystal templating, ion sputtering and chemical etching using nanosized Au particles as the etching catalyst. Since self-organized polystyrene spheres were used as a mask, Au particles were selectively deposited at sites resulting in the formation of Au honeycomb pattern on GaAs. Microsized GaAs column arrays were achieved by chemical etching of GaAs, where the honeycomb-patterned Au metals were deposited. Although ordered column structures were obtained for both planes, different anisotropic etching patterns were observed by Au-assisted chemical etching between n-GaAs (100) and (111). The crystal-face orientation strongly affects the etching morphology and the rate of metal-assisted chemical etching.

Angle-resolved XPS structural investigation of GaAs surfaces

A plasma etching profile simulator was developed to investigate the evolution of pattern profiles in various materials under different plasma conditions. This simulator is based on a two-dimensional cellular method. The model is fed with input parameters that include angular dependent etch yield, ion and neutral angular distribution, and plasma and material characteristics. It has been tested by comparison with published profiles of Si sputtering and SiO2 ion-assisted chemical etching in argon and chlorine plasmas. Observed microtrenching and bowing have been well reproduced by the simulator. The simulator was further used to examine etching for dimensions below nanometer in low-pressure high-density plasmas. In the case of Si sputtering, trenches of 100 nm depth and 30 nm or less width show unusual lateral etching. Finally, the effect of positive charge accumulation on an insulated mask resulting from negative bias voltage on the wafer was studied. This charge accumulation causes a deflection of ion trajectories. Considering this phenomenon, very isotropic etched profiles were found, in good agreement with in-house experimental profiles of platinum sputtering in argon plasma. The simulator developed is intended to be used for any material and mask combination in order to predict the profile evolution under various plasma conditions and pattern dimensions from micrometer to nanometer.

All β-SiC films grown using on-axis (001) Si substrates that have been examined with transmission electron microscopy exhibit a high density of interfacial twins, stacking faults, and antiphase disorder. The antiphase boundaries can be decorated by chemical etching, sputter etching, wet oxidation, and β-SiC growth in the presence of diborane. All traces of antiphase disorder are eliminated when the heteroepitaxial growth is carried out on vicinal (001) Si substrates that are tilted 2° about a 〈110〉 axis. In addition, growth on the off-axis Si produces β-SiC films that are significantly smoother than on-axis films. The density of stacking faults is apparently unaffected by growth on the off-axis substrates.

Dry-etching durabilities of poly(2-vinylnaphthalene-co-methyl methacrylate), the blend of poly(2-vinylnaphthalene) and poly(methyl methacrylate) [PMMA], and poly(α-methylstyrene-co-methyl methacrylate) films were studied as a function of vinylnaphthalene or α-methylstyrene content against four types of dry etching: 1) O2 plasma etching ( O2 PE), 2) O2 reactive ion etching ( O2 RIE), 3) Ar+ sputter etching (Ar SE), and 4) Ar ion beam etching (Ar IBE). Since the etching depth increased linearly with etching time the two-component polymer films were regarded to be etched uniformly without selected removal of aliphatic monomer units. Substantial enhacement of the durability was observed by incorporating or blending small amounts of aromatic moiety into PMMA for physical etching (Ar SE, Ar IBE) and physical/chemical etching ( O2 RIE) as well as chemical etching ( O2 PE). O2 RIE is a synergetic process involving both physical bombardment and chemical reaction.

Reflection high‐energy electron diffraction (RHEED) measurements of the microscopic surface roughness of polished GaAs(100) wafers subjected to various surface cleaning procedures are presented. These include Br2:MeOH, HCl, and sputter etching, each followed by annealing in UHV. The results indicate that chemical etches such as Br2:MeOH and HCl produce large three‐dimensional (3D) asperities that cannot be removed by annealing, while sputter etching produces less roughness. Quantitative values of the mean asperity height are presented. Measurements on GaAs(100) are compared with results from sputter‐etching‐induced roughness on cleaved GaAs(100), which initially has a nearly defect‐free surface. Remanent roughness is always at least 2 or 3 atomic layers, with terrace widths of 100 Å or less.

The problem of carbon contamination on extreme ultraviolet (EUV) optics, causing unacceptably low reflectivity in mirrors, must be solved before industry will adopt the technology on a production scale. Breaking vacuum, removing and then cleaning mirrors is a time-consuming and expensive method for dealing with the problem. A safe yet effective in situ method for cleaning EUV optics and maintaining vacuum chamber cleanliness is important for progress in EUV lithography. Carbon contamination has also been a problem for the scanning electron microscopes (SEMs) leading to reduced image quality. The use of low power downstream plasma cleaner has been shown to be effective in removing carbon contamination from SEMs. The plasma dissociates oxygen molecules into neutral oxygen radicals. These radicals flow throughout the SEM vacuum chamber and chemically remove the carbon contamination. Since the process works by chemical etch and not by sputter etch, the capping layer on EUV mirrors will not be damaged by the cleaning process. The production of chemically etching oxygen radicals by plasma cleaning was measured using a quartz crystal microbalance. The effectiveness of the downstream plasma cleaning process was also tested on EUV mirrors.

The requirements for high-fidelity, anisotropic etching are discussed. A brief discuss­ ion on the various dry etch techniques available is followed by a description of a batch reactive sputter etch system that fulfills all patterning requirements. Examples of results obtained with this system are given and demonstrated with SEM photographs.IntroductionWith the progress of the I. C. industry toward the VLSI regime, many methods of device processing used previously are being extended to their limits as feature size shrinks toward ly. It is well known that photolithograpic techniques capable of generating such features became available in recent years. In order to transfer these fine patterns into underlying substrate materials with the maximum amount of pattern fidelity, a method of well controlled anisotropic etching is required. Conventional pattern transfer by wet etchants is unable to provide this and, in general, has found its application limited to 4 ym and above features. Dry processes, such as sputtering, ion milling, plasma chemical etching and reactive sputter etching, have become increasingly attractive due to their better resolution, and increased dimensional and etch profile control. Of these, reactive sputter etching has shown itself to be capable of providing the best overall etch results.This paper will review the requirements of pattern transfer for VLSI applications, summarize the advantages and limitations of various dry etching techniques and describe the results obtained with a new batch reactive sputter etch system.Pattern transfer requirementsIn order to achieve higher packing density and better circuit performance future VLSI devices will have features in the micron and sub-micron range. The transfer of these patterns into the underlying layers will require the dry etch process and reactor design to produce the following results in order to provide a high yield:1. Controlled profile of etch features from highly anisotropic to a tapered profile.2. High selectivity in etching relative to masking materials, substrate and exposed surfaces of system.3. Minimal damage of masking materials to allow use of soft-baked resist without reticula­ tion. .4. High uniformity of etching - both etch rate and finished linewidth.5. A clean and smooth etched surface - no trenching, surface roughness, or surface deposits.6. No radiation damage or metal contamination.7. No loading effects - neither reactor nor proximity.8. Sequential etching - the ability to change or alter etch gases and/or operatingconditions during one etch run. 9 0 Reproducibility of etch results and reliability of etch results combined with highthroughput of reactor operation as well as minimum maintenance.Characteristics of reactive sputter etchingDry etching generally involves the creation of a glow discharge by the application of an electric field (DC or AC) between two electrodes in a partially evacuated chamber. The various techniques can be divided into three groups: ion etching (ion milling and sputter etching), chemical plasma etching, and reactive sputter etching.Ion etching involves the creation and subsequent acceleration of inert ions toward the sample to be etched. Etching takes place purely by physical means - momentum transfer between the energetic ion and the material being etched. The technique offers high re­ solution but suffers from low etch rates, poor selectivity, faceting, trenching, redeposition and low efficiency.

We have studied a process for filling narrow spaces between adjacent metallic conductors (gaps). The process consists of cycles of deposition of by plasma‐enhanced chemical vapor deposition (PECVD) and sputter etching in Ar. For a fixed process and metal thickness, as the gaps decrease in size, i.e., as the aspect ratio, increases, a region which etches rapidly in a solution (BHF) is formed in the gap. At higher values of AR, physical voids are formed. The ability to fill the gaps with ‘good’ quality oxide is a function not only of AR but of the side‐wall angle and the thickness of the metal as well. Filaments of an unidentified material can also be detected within the gap. Higher AR spaces can be filled if more of the oxide is sputtered. However, decreasing the thickness of the PECVD film deposited before etch‐back, or using instead of Ar, has the opposite effect. The material in the gap which has a high etch rate in BHF does not etch at a higher rate in a plasma; therefore, misalignment of vias is not a concern unless physical voids have been formed. The dielectric constant of the PECVD is unchanged by sputter etching; the break‐down strength of the oxide is degraded. However, after the structure is completed by the deposition of a thick PECVD layer, the effect of the dep/etch cycles on the break‐down strength of the composite is not detectable.

Investigating the robustness of locators in template-based Web application testing using a GUI change classification model

Fabrication of plasmonic structures on a gold film is a well-established approach to improve the performance of surface plasmon resonance (SPR) sensors. However, traditional fabrication techniques, such as photolithography, electron beam lithography (EBL), and focused ion beam (FIB) milling, often involve complex procedures and costly equipment. In this study, we present a mask-free, convenient method to fabricate robust plasmonic structures on the surface of z-cut α-quartz by combining femtosecond laser-induced modification with chemical etching for high-sensitivity Kretschmann configuration SPR sensing. We find that the etching process of laser-modified α-quartz in ammonium bifluoride (NH4HF2) solution proceeds in two distinct stages: isotropic etching and anisotropic etching. By comparing the etching morphology of the craters ablated by femtosecond laser with wavelengths of 400 and 800 nm, we observe that due to the lower threshold fluence and steeper crater profile, the 400 nm laser can induce more pronounced anisotropic etching, leading to sharper inverted pyramid structures. A 5-nm-thick Cr film and a 50-nm-thick Au film are then deposited on the patterned quartz surface, which is used to detect the refractive indices (RIs) of glycerol solutions as an SPR sensor. The inverted pyramid structures can enhance the localized electric fields, causing a red shift of the resonance peak and thereby improving the sensitivity of the SPR sensor. The sensor demonstrates a sensitivity of 4662.21 nm/RIU, achieving a 21.51% improvement compared with a traditional SPR sensor with a plain Au film under the same light incident angle. The refractive index (RI) resolution reaches 2.7 × 10-5 RIU, and the figure of merit (FOM) is 85.36 RIU-1. Femtosecond laser-assisted chemical etching offers an efficient and convenient method for fabricating plasmonic structures on α-quartz. The high-sensitivity SPR sensors developed through this approach demonstrate promising potential for applications in fields such as medical diagnostics, disease detection, and environmental monitoring.

Dry etching of AlN films using the plasma generated by fluoride