Substrate Fabrication Process Research Articles

Planting gold nanoflower for harvesting reproducible SERS substrate

Surface-enhanced Raman scattering (SERS) is an ultrasensitive analytical method which has been applied in many fields, and the reproducibility of the substrate is important for reliable SERS analysis. In present work, an innovative method inspired by the flower planting process is put forward to acquire gold nanoflower (AuNF) SERS substrate. Three steps (digging holes, sowing the gold nanoseeds and seeds grow into gold nanoflowers) are included in the substrate fabrication process, and the influence of preparing conditions (like reacting time and Na3Au(SO3)2 concentration) on the substrate morphology and SERS performance are investigated. The acquired AuNF substrate not only exhibits good SERS performance but also possesses excellent reproducibility while being used to detect the rhodamine 6G (R6G) molecular. The relative standard deviation (RSD) of Raman signals among substrates acquired in distinct batches (substrate-to-substrate) is as low as 6.67 %. Since the AuNF substrate is prepared by the wet chemistry route based on seed-mediated growth and there are no expensive reagents or complicated process used, the new process to obtain AuNF substrate is cost-effective and easy to scale up.

Development of Roll-to-Roll Manufacture Process for Stretchable Device Substrate

As the next generation of smart devices, many stretchable devices with have been developed. In this process, it is necessary to fabricate stretchable substrates and electrodes. However, in many studies, stretchable devices are currently manufactured by hand. Considering future social implementation, it is important to realize a mass production process for substrates and wiring. In this study, we conducted a PoC of a mass production process for stretchable devices by combining a substrate fabrication process by Roll-to-Roll (R2R) and a liquid metal wiring fabrication process by dispensing. To realize this process, we assembled a new R2R system by incorporating a slot die coater and applicator, which is the R2R coating process, and a corona treatment system to improve the wettability of polymeric materials into the R2R process equipment. Using this equipment, we evaluated the device at 50% elongation and fabricated a large scale stretch device.

Bioinspired Integration of Naturally Occurring Molecules towards Universal and Smart Antibacterial Coatings

AbstractSurface‐independent smart antibacterial coatings with on‐demand antibiotics release profiles have attracted increasing attention in medical instruments, antibiotics delivery platforms, and implanted devices. Although several approaches have been well documented, the facile preparation of antibacterial coatings onto universal substrates with high antibiotics loading efficiencies, tunable drug release profiles, and excellent antibacterial performances is still met with many challenges, especially related to the redundant coating material synthesis and selective substrate fabrication process. To resolve this issue, the authors report a facile and robust fabrication method towards smart antibacterial coating surfaces on various substrates via a one‐pot integration of two types of naturally occurring building blocks, aminoglycosides and protocatechualdehyde in the presence of plant enzyme horseradish peroxidase. The simultaneous dynamic imine bonds formation and enzymatic polymerization within the system during the one‐pot reaction enable the facile fabrication of diverse surface‐independent smart antibacterial coatings, which can demonstrate several promising features including high drug loading and dynamic (i.e., pH‐responsive) properties, tunable and on‐demand antibiotics release behaviors, and efficient antibacterial activities both in vitro and in vivo. This work may offer new opportunities towards the robust and universal antibacterial coating materials by the bioinspired integration of all natural building blocks.

Miniaturized and high-performance RF packages with ultra-thin glass substrates

Advanced RF packages are demonstrate with active (low-noise amplifier, RF switch) and passive integration in ultra-thin 3D glass packages with miniaturization and enhanced performance. The novelty of this RF packages is three-fold: 1) Ultra-thin 100 μm glass, 2) Double-side thinfilm RF circuits interconnected with Through-Package Vias (TPVs), and 3) Direct assembly of the glass-core package to the board with Land Grid Array (LGA) connections. An innovative double-via process, starting from prefabricated vias in bare glass, polymer filling and via drilling, is utilized for a robust and high-yield substrate fabrication process. Scalable and low-cost panel laminate processes are utilized to form the RF circuits on the build-up layers. The performance benefits are demonstrated through interconnect loss, impedance match, electrical gain and noise figure measurements. Compared to existing RF substrates, the glass substrates show 2.5X miniaturization in substrate thickness with extensibility to thinner substrates.

Investigation of Mass-Produced Substrates for Reproducible Surface-Enhanced Raman Scattering Measurements over Large Areas.

Surface-enhanced Raman scattering (SERS) is a versatile spectroscopic technique that suffers from reproducibility issues and usually requires complex substrate fabrication processes. In this article, we report the use of a simple mass production technology based on Blu-ray disc manufacturing technology to prepare large area SERS substrates (∼40 mm2) with a high degree of homogeneity (±7% variation in Raman signal) and enhancement factor of ∼6 × 106. An industrial high throughput injection molding process was used to generate periodic microstructured polymer substrates coated with a thin Ag film. A short chemical etching step produces a highly dense layer of Ag nanoparticles at the polymer surface, which leads to a large and reproducible Raman signal. Finite difference time domain simulations and cathodoluminescence mapping experiments suggest that the sample microstructure is responsible for the generation of SERS active nanostructures around the microwells. Comparison with commercial SERS substrates demonstrates the validity of our method to prepare cost-efficient, reliable, and sensitive SERS substrates.

A study on grid-stiffened multi-functional composite structures with radiation spot shielding

This paper deals with alternative multi-functional structures by using grid-stiffened composite panel with excellent bending stiffness and lightweight characteristics. The grid-stiffened multi-functional structure can provide an array of available rooms for integrating multiple electronic circuitries into structure with ease. The substrate fabrication process was proposed and the grid-stiffened multi-functional structure equipped with several electronics and interfaces was built up. In order to improve the thermal conduction capability, pitch-based carbon fibers were applied to facesheet of the multi-functional structure. The spot shielding technique was also proposed to enhance the radiation shielding at the selective region sensitive to radiation, and the lightweight radiation spot shielding plate was fabricated with multi-layered laminate of CFRP and tungsten foil. The radiation shielding effectiveness of the multi-functional structure with spot shielding plate was demonstrated by proton beam irradiation test. Through the test, it was found that the radiation spot shielding plate has comparable proton-shielding performance to aluminum but more lightweight characteristics than aluminum. Grid-stiffened MFS with radiation spot shielding can be an effective measure for accommodating lots of electronics into structure, providing dramatic mass and volume savings in spacecraft design.

Combination of improved cosine similarity and patent attribution probability method to judge the attribution of related patents of hydrolysis substrate fabrication process

The paper studies the attribution of patents by innovatively establishing a combination of improved cosine similarity concept and patent attribution probability method for hydrolysis substrate fabrication process in order to enhance the speed and accuracy for judgment of patent attribution. For the improved cosine similarity method innovatively established in the paper, all the vocabularies of important technical words or functional words in patent documents are regarded as a number of vector dimensions. The normalized numerical values of these vocabularies are regarded as the weights of these technical words or functional words. They are substituted in a formula of improved cosine similarity. Regarding the patent attribution probability method, it applies the normalized numerical values of the various clusters of technical or functional words as well as the formula of probability method to judge which technical category or functional category that a patent is attributed to. As the study innovatively combines improved cosine similarity with patent attribution probability method, before employing patent attribution probability method for a patent document, the study firstly uses improved cosine similarity to check with the cluster of patent group words having high relativity, and rule out the unrelated technical categories or functional categories that the patent is not attributed to, so as to decrease the number of categories for calculation and the time to calculate which technical category or functional category that a patent is attributed to when using patent attribution probability method, and to achieve a method that can more rapidly and accurately judge which technical category or functional category that a patent is attributed to.

Silicon Photonic Integration Platform—Have We Found the Sweet Spot?

The current trend in silicon photonics towards higher levels of integration as well as the model of using CMOS foundries for fabrication are leading to a need for standardization of substrate parameters and fabrication processes. In particular, for several established research and development foundries that grant general access, silicon-on-insulator wafers with a silicon thickness of 220 nm have become the standard substrate for which devices and circuits have to be designed. In this study we investigate the role of silicon device layer thickness in design optimization of various components that need to be integrated in a typical optical transceiver, including both passive ones for routing, wavelength selection, and light coupling as well as active ones such as monolithic modulators and on-chip lasers produced by hybrid integration. We find that in all devices considered there is an advantage in using a silicon thickness larger than 220 nm, either for improved performance or for simplified fabrication processes and relaxed tolerances.

Substrates with patterned extracellular matrix and subcellular stiffness gradients reveal local biomechanical responses.

A substrate fabrication process is developed to pattern both the extracellular matrix (ECM) and rigidity at sub-cellular spatial resolution. When growing cells on these substrates, it is found that cells respond locally in their cytoskeleton assembly. The presented method allows unique insight into the biological interpretation of mechanical signals, whereas photolithography-based fabrication is amenable to integration with complex microfabricated substructures.

Tensile-strained germanium-on-insulator substrate fabrication for silicon-compatible optoelectronics

We present a method to fabricate tensile-strained germanium-on-insulator (GOI) substrates using heteroepitaxy and layer transfer techniques. The motivation is to obtain a high-quality wafer-scale GOI platform suitable for silicon-compatible optoelectronic device fabrication. Crystal quality is assessed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy. A biaxial tensile film strain of 0.16% is verified by XRD. Suitability for device manufacturing is demonstrated through fabrication and characterization of metal–semiconductor–metal photodetectors that exhibit photoresponse beyond 1.55 μm. The substrate fabrication process is compatible with complementary metal–oxide–semiconductor manufacturing and represents a potential route to wafer-scale integration of silicon-compatible optoelectronics.

Simulation and measurement of inset‐fed microstrip patch antennas on BiNbO4 substrates

AbstractThis work presents an experimental investigation of the properties of microstrip patch antennas on bismuth niobate ceramic substrates. The substrate fabrication process and characterization are described. Several prototypes were built and measured for wireless communication systems. A good agreement was observed between measured and simulated results. The very high electrical permittivity of the ceramic substrate provided a reduction of the antenna dimensions. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1034–1036, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25098

Silver Nanodesert Rose as a Substrate for Surface-Enhanced Raman Spectroscopy

Silver galvanic displacement on silicon has been employed to produce large-area reproducible substrates, with morphology similar to that of the natural desert rose but on the micrometer scale. The process is based on an extremely simple wet chemistry approach using only AgF and KF, as silver and fluoride sources. A key element is the absence of HF in the deposition solution, which has been commonly used in previous silver galvanic displacement processes. The new process affords a higher degree of control in the redox reaction than those reported previously. The structures formed in this manner possess a large area-to-volume ratio with a high density of rough silver flakes uniformly distributed across the substrate. The silver morphology on the nanometer scale is shown to provide an excellent platform for surface-enhanced Raman spectroscopy (SERS), yielding detection levels for trans-1,2-bis(4-pyridyl)ethylene, 4-mercaptopyridine, and Rhodamine 6G in solution down to ppb, ppt, and ppq limits, respectively. The SERS reproducibility on the substrate was verified by monitoring the signal intensity variations across the sample. The simplicity of the substrate fabrication process, as well as the excellent uniformity, opens up opportunities for the quantitative and in-field chemical trace analysis using these substrates.

Fabrication of the cyclical fluid channel using the surface acoustic wave actuator and continuous fluid pumping in the cyclical fluid channel

A surface acoustic wave (SAW) device has been reported as a micro fluid device such as a pump of a water droplet so far (Renaudin et al. in μTAS, pp 599–601, 2004, 1:551–553, 2005; Sritharan et al. in Appl Phys Lett 88:054102, 2006; Wixforth in Anal Bioanal Chem 379:982–991, 2004; Yamamoto et al. in μTAS, pp 1072–1074, 2005). The SAW device is an interdigital transducer (IDT) fabricated on the piezoelectric substrate only. IDTs are advantageous in terms of integration, miniaturization, free position setting on the substrate and simple fabrication process because of their simple structure. Therefore, the SAW device is easy to apply to integrated chemical system such as lab-on-a-chip. The SAW drives the liquid homogenously by the transmission of surface vibrations of the substrate. Thus, both ends of the channel for pressure loading are not necessary to pump the liquid by using the SAW. The SAW can pump the liquid in both of a closed channel and an opened channel, although continuous flow pumping using an external pump is difficult for no loading pressure in the closed fluid channel. In this paper, we proposed and fabricated the micro fluid devices combined cyclical fluid channel and SAW actuator for liquid pumping. This device is fabricated on a piezoelectric substrate (LiNbO3) with UV photolithography and wet etching. Structure material of cyclical fluid channel is epoxy photoresist SU-8 100. Then, it is demonstrated to continuous flow pumping and reciprocal flow pumping in the channel. As a result of optimization of a SAW pump’s structural parameter, 32.5, 71.3 and 108.0 mm/s are achieved in the 500, 1,000 and 2,000 μm channel width as a maximum flow velocity.

Strained Si on insulator technology: from materials to devices

SiGe-free strained Si on insulator (SSOI) is a new material system that combines the carrier transport advantages of strained Si with the reduced capacitance and improved scalability of thin film silicon on insulator (SOI). We demonstrate fabrication of 20% Ge equivalent strain level SSOI substrates with Si thicknesses of 100 and 400 Å by hydrogen-induced layer transfer of strained Si layers from high quality graded SiGe virtual substrates. The substrate properties are excellent: wafer scale strained Si film thickness uniformities are better than 8%, strained Si surface roughnesses are better than 0.5 nm RMS, and robust tensile strain levels are maintained during anneals as long as 80 min at 1100 °C. Fully depleted n-MOSFET electrical results show that biaxial tensile strain, and hence enhanced mobility, is fully maintained in the 400 Å 20% SSOI films through the substrate and device fabrication processes, even after a generous FET fabrication thermal budget. Long channel devices exhibit nearly ideal subthreshold slopes of 66 mV/decade and exhibit 112% electron mobility enhancements at N inv=1×10 13 cm −2, identical to devices on bulk strained Si substrates. Furthermore, a photoemission microscopy study was used to confirm that the useable SSOI layer thickness significantly exceeds the critical thickness for fabrication of bulk strained Si FETs without deleterious leakage current effects. The fabrication of epitaxially defined, thin strained Si layers directly on a buried insulator is an ideal platform for future generations of Si-based microelectronics.

An integrated process modeling methodology and module for sequential multilayered substrate fabrication using a coupled cure-thermal-stress analysis approach

An integrated process modeling methodology using a coupled cure-thermal-stress analysis approach has been developed to determine the evolution of warpage and stresses during the sequential fabrication of high-density electronic packaging structures. The process modeling methodology has been demonstrated, for example, with a bi-layer structure consisting of a 3 mil (76.2 /spl mu/m) thick Vialux 81 photo-definable dry film (PDDF) polymer on a silicon substrate. Extensive material characterization of the thermo-mechanical properties of the thin film polymer is presented, including the development of a viscoelastic material model. The predicted warpage values have been validated with shadow Moire experiments, while the predicted stress values have been validated with experimental data using the Flexus Thin Film Stress Measurement Apparatus. Good agreement is seen between the predicted and the experimental warpage and stress values during the entire cure cycle. Finally, the importance of incorporating viscoelastic polymer behavior and processing history is emphasized in the context of developing the multi-layered high-density wiring integrated substrate fabrication process.