Good Thickness Uniformity Research Articles

Battery-free flexible wireless temperature sensing for food storage

The method of monitoring food temperature during food storage needs to be improved to continuously and accurately perceive the temperature of the food in the package to ensure the quality and safety of the food during storage. This paper proposes and develops a battery-free flexible wireless temperature sensing system (BFTS) for food storage. The BFTS consists of a battery-free flexible wireless temperature sensing tag (BFTT), a wireless reader, and a personal computer (PC). The BFTT developed in this paper has good flexibility and can be placed inside the food package to realize the continuous monitoring of temperature changes. The flexible circuits of the BFTT were fabricated by laser engraving laser-induced graphene (LIG) −copper (Cu) plating film made with Cu plating on LIG. The LIG-Cu plating film has good thickness uniformity, electrical conductivity, and laser engraving processability. The antenna of BFTT has good performance. The wireless reader is connected to the PC using a data line, and the BFTT communicates wirelessly with the wireless reader using ultra-high frequency (UHF) radio frequency identification (RFID). The BFTT was realized by the wireless radio frequency (RF) as the supply power from the wireless reader. The BFTS could realize the temperature monitoring of food stored at 0℃ and −18℃, and it has the advantages of low cost, simple manufacturing process, and low energy consumption, which could be used to continuously and accurately monitor the inside temperature of the food packages. Overall, the LIG-Cu plating film developed in this paper could be used in the fabrication of flexible circuits, and the temperature monitoring inside food packages realized by the BFTS has potential applications in actual food storage.

Study of Nb2O5 High-k Dielectric Material Deposited By Atomic Layer Deposition for Metal-Insulator-Metal Capacitor

Metal-Insulator-Metal (MIM) capacitors are important components in many electronic devices, including memory devices, filters, and oscillators. The performance of these devices depends strongly on the electrical properties of the dielectric layer. The application of new high-k materials can improve the properties of modern capacitors such as leakage current and capacitance density. However, it is necessary to understand the deposition conditions of both electrode and dielectric materials in order to master the dielectric properties in future MIM capacitors.One potentially interesting high-k material is niobium pentoxide (Nb2O5) with a wide band gap (3.6 eV) and high refractive index (n=2.3 @633 nm) deposited by Atomic Layer Deposition (ALD) using niobium (V) ethoxide as niobium precursor at 180°C and H2O as reaction agent and oxygen source. Nb2O5 films were deposited directly on a silicon (Si 100) substrate or on a 10nm of titanium nitride (deposited by ALD on Si substrate, n=1.4@633 nm). The Nb2O5 films were deposited with a good film thickness uniformity on the 6-inches of the wafers with a thickness ranging from 20 to 60 nm on each sample. The deposition was done under a suitable ALD temperature of 200-300 °C. In order to investigate the film growth, structure, morphology and optical properties, the samples were characterized by spectroscopic ellipsometry (SE), scanning electron microscopy (SEM), X-Ray diffraction (XRD) and atomic force microscopy (AFM). The as-deposited films were then annealed in a furnace at temperature ranging from 500 to 650°C under N2 atmosphere.Subsequently, a MIM structure (Al/Nb2O5/TiN) was produced by adding a second aluminum layer deposited at 250°C on a Nb2O5/TiN/Si stack by the sputtering method. The surface of the second electrodes was aimed to have 0.1-1.0 mm2 to confirm the surface dependency of the capacitance value. The electrical properties of Nb2O5 dielectric layer such as dielectric constant, breakdown voltage and leakage current at possible user voltage were measured on this last structure. The low leakage current density is desirable for MIM capacitors as it helps to minimize energy loss and increase the energy storage capabilities of the capacitors. The obtained J-E curve was compared to some electrical conduction mechanisms to identify its electrical conduction behaviors. The barrier height of the F-N tunneling mechanism was determined by fitting the experimental data to the F-N equation. These measurements indicate that the electrical properties of the Nb2O5 material produced by ALD with specific settings are promising for the application in capacitors. These results provide new insight into our understanding of the application of Nb2O5 realized by ALD for the MIM capacitor.

DEVELOPMENT AND EVALUATION OF GASTRIC FLOATING TABLETS OF RIBOFLAVIN USING BOX-BEHNKEN DESIGN

Objective: To develop and evaluate gastric floating tablets of riboflavin that was thermally fused using an experimental design method. Methods: Gastric floating tablets were developed using the Box-Behnken design. The effect of sintering on various tablet properties is assessed. The prepared floating tablets were tested for characteristics like usual tablet quality control tests with special emphasis on buoyancy studies and in vitro drug release studies. Results: The drug-excipient incompatibility studies indicated no interactions between riboflavin and carnauba wax. Sintering the powder at 1200, °C partially decreased its crystallinity and improved drug release for up to 16 h. The tablets demonstrated good flow properties, acceptable hardness, low friability, and uniformity in thickness and diameter. Statistical models successfully optimized the formulation to achieve desired characteristics and practical compressibility. The optimal amounts of the variables, according to Design Expert® 12 software, were 59.19 mg of carnauba wax, 14.63% w/w of sodium bicarbonate, a sintering temperature of 74.68 °C, and a sintering exposure time of 1.99 h. Conclusion: In vitro dissolution studies were conducted on the optimized formulation to verify the model's predictions. The experimental results closely matched the predictions. The optimized formulations showed a floating lag time of 104 seconds and a floating duration of 12.3 h. The obtained T90 was found to be 11.3 h which followed zero order kinetics with a non-Fickian diffusion mechanism.

Liquid Shear Exfoliation of MoS2: Preparation, Characterization, and NO2-Sensing Properties.

2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS2 nanosheet dispersions. MoS2 thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS2 was studied using ς-potential, UV-visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS2 thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS2 layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS2 thin film exhibits good conductivity and a linear I-V curve response, indicating good ohmic contact between the MoS2 film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS2 film as a sensing layer. The performance of the MoS2-chemiresistive sensor for NO2 was assessed by being exposed to different concentrations of NO2 (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO2; the response decreases as the working temperature increases.

Improvement of the uniformity of structural and electrical properties of transparent conductive Al-doped ZnO thin films by inductively coupled plasma-assisted radio frequency magnetron sputtering

Transparent conductive Al-doped Zinc oxide thin films were deposited on glass substrates by conventional radio frequency magnetron sputtering (C-RFMS) and inductively coupled plasma-assisted radio frequency magnetron sputtering (ICP-RFMS) methods. The structural and electrical properties of films were studied as a function of the radial position (r) of the substrate in both methods. A good thickness uniformity was obtained in ICP-RFMS, while a significant decrease in film thickness was observed at r=30mm (erosion zone) in C-RFMS. The c-axis orientation was achieved in all positions in ICP-RFMS, while crystallinity was degraded at r≥25mm in C-RFMS. Low resistivity ρ of the order of 10−4Ωcm was obtained at all positions in ICP-RFMS, while ρ was rapidly increased at r≥30mm in C-RFMS. In ICP-RFMS, high-energy ion bombardment is suppressed due to the modified plasma density profile and lower space potential. As for transparency, the sample prepared at r=0mm in ICP-RFMS showed an average visible transmittance of 81%, higher than that in C-RFMS. Throughout the study, it was demonstrated that ICP-RFMS method was promising to improve the radial distribution of structural, electrical, and optical properties of Al-doped ZnO thin films.

KNN lead-free piezoelectric films grown by sputtering

Potassium sodium niobate [(K,Na)NbO3, KNN] films are promising lead-free piezoelectric materials for microelectromechanical systems (MEMS) devices. We previously developed technologies for forming high-quality KNN films by sputtering, which showed excellent piezoelectric properties comparable to lead zirconate titanate (PZT) films. In the present study, we addressed several challenges with the aim of introducing KNN films into commercialized MEMS devices. First, we optimized the dielectric and piezoelectric properties to realize a suitable performance for actuator and sensor devices. The sensor-type KNN films had a low dielectric constant (248) and a self-poling function, which are greatly beneficial for sensor device performance and the fabrication process. The actuator-type KNN films had a very high e31 value of −13.5 C/m2, which is almost comparable to the top level of PZT films. Next, we found that the DC stress lifetime of KNN films strongly depended on the material used for the adhesion layer of the top electrode. When we used a Pt/RuO2 top electrode, the actuator-type KNN films had a long lifetime (>130 000 s, 300 kV/cm and 200 °C), which is long enough to be used for commercialized MEMS devices. Furthermore, we realized 8-in. KNN wafers with good thickness uniformity across the wafer (±3.5%) by introducing a mass-production-ready sputtering tool: the EB-2500 produced by Canon Anelva. In the near future, these promising results will open the way to replace PZT with KNN in the piezoMEMS industry.

Development and In Vitro-Ex Vivo Evaluation of Novel Polymeric Nasal Donepezil Films for Potential Use in Alzheimer's Disease Using Experimental Design.

The objective and novelty of the present study is the development and optimization of innovative nasal film of Donepezil hydrochloride (DH) for potential use in Alzheimer’s disease. Hydroxypropyl-methyl-cellulose E50 (factor A) nasal films, with Polyethylene glycol 400 as plasticizer (factor B), and Methyl-β-Cyclodextrin, as permeation enhancer (factor C), were prepared and characterized in vitro and ex vivo. An experimental design was used to determine the effects of the selected factors on permeation profile of DH through rabbit nasal mucosa (response 1), and on film flexibility/foldability (response 2). A face centered central composite design with three levels was applied and 17 experiments were performed in triplicate. The prepared films exhibited good uniformity of DH content (90.0 ± 1.6%–99.8 ± 4.9%) and thickness (19.6 ± 1.9–170.8 ± 11.5 μm), storage stability characteristics, and % residual humidity (<3%), as well as favourable swelling and mucoadhesive properties. Response surface methodology determined the optimum composition for flexible nasal film with maximized DH permeation. All selected factors interacted with each other and the effect of these interactions on responses is strongly related to the factor’s concentration ratios. Based on these encouraging results, in vivo serum and brain pharmacokinetic study of the optimized nasal film, in comparison to DH oral administration, is ongoing in an animal model.

Ferris-wheel-assisted parylene-C dielectric deposition for improving organic thin-film transistor uniformity

Organic thin film transistor is one of the most promising electronic device technologies for flexible and printed electronics, but device uniformity remains a challenge for large-scale integration circuit design. Despite the advances in semiconductor layers, the quality of dielectric layers is equally important. Parylene-C dielectric has good intrasample thickness uniformity, but demonstrates significant variation among samples fabricated at the same time, thus causing device non-uniformity. In this study, we present a two-dimensional (2D) sample rotation method using a Ferris wheel to improve the thickness uniformity of parylene-C dielectrics. The Ferris wheel averages the deposition rate of parylene-C dielectric on different samples over an identical spherical space, rather than over different horizontal planes by the conventional one-dimensional sample rotation with a rack. The dielectrics fabricated on different cabins of the Ferris wheel demonstrate better thickness uniformity than those fabricated on different floors of the rack, and thus better uniformity of transistors. Specifically, using the 2D rotation Ferris wheel, the coefficient of variation of dielectric thickness is lowered to 0.01 from 0.12 (which uses the conventional rack); the coefficients of variation for the on-state drain current, process transconductance parameter, and threshold voltage of the fabricated transistors are improved to 0.15, 0.16 and 0.08, from 0.33, 0.20 and 0.14, respectively. The improved device uniformity has the potential in complicated flexible circuit design for advanced applications such as edge intelligence.

MOCVD Grown HgCdTe Heterostructures for Medium Wave Infrared Detectors

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing.

Copolyamide-Imide Membrane with Low CTE and CME for Potential Space Optical Applications.

Polyimide diffractive membrane lens can be used in space optical telescope to reduce the size and mass of an imaging system. However, traditional commercial aromatic polyimide membrane is hard to meet the challenging requirements of dimensional stability and optical homogeneity for optical use. Based on molecular structure design and the optimization of fabrication process, the prepared copolyamide-imide membrane achieved the desired performance of membrane as an optical material. It showed a very low coefficient of thermal expansion (CTE), which is 0.95 ppm/°C over a temperature range of −150–100 °C and relatively low coefficient of moisture expansion (CME), which is only 13.30 ppm/% RH (0~90% RH). For the optical use, the prepared copolyamide-imide membrane (φ200 mm) achieved good thickness uniformity with wave-front error smaller than λ/30 (λ = 632 nm) in RMS (root mean square). Besides, it simultaneously meets the optical, thermal, and mechanical requirements for space telescope use. Copolyamide-imide membranes in this research with good comprehensive performance can be used as large aperture membrane optical system architectures.

Effect of Dip-Coating Cycles on the Structural and Performance of ZnO Thin Film-based DSSC

Deposition of thin film with good thickness uniformity and quality for fabrication of thin film-based dye-sensitized solar cells is a critical factor that determines the reliability and consistency of its photovoltaic performance. In this work, dip-coating method was used for the deposition of ZnO thin films on fluorine-doped tin oxide glass substrates. The structural, electrical and optical properties of these ZnO thin films were characterized by XRD, FESEM, four-point probe, UV–Vis spectroscope and room temperature PL spectroscope. The study showed that the thickness of ZnO thin film could be adjusted by the number of dipping cycles. By increasing the dip-coating cycles, the thickness, crystal quality and absorbance of visible light of ZnO thin films increased whereas the sheet resistance of ZnO thin films decreased. As a consequence, the photovoltaic performance of DSSCs improved with maximum conversion efficiency of 0.68% at 3 cycles of dip coating. Nevertheless, formation of macro-defects such as pores and cracks in thick ZnO thin films became the dominant factor that deteriorated their conversion efficiency down to 0.19% (at 11 cycles).

Fabrication and evaluation of Olopatadine hydrochloride ocular inserts

Development of the novel delivery provides optimal drug delivery via facilitated transcorneal penetration and ultimately improved retention time in eye. The present study was to fabricate and evaluate the performance of ocular inserts of Olopatadine hydrochloride by consuming polymers such as hydroxypropyl methylcellulose, gelatin, and chitosan at various concentrations with different plasticizers using solvent casting technique. Prepared formulations were evaluated for thickness, weight variations, drug content, surface pH, swelling studies, and in vitro drug release. Fourier transform infrared spectroscopy studies showed that interaction occurred between polymer and drug, and successful drug entrapment occurred in the matrix. All formulations showed excellent film-forming capacity with good thickness and weight uniformity. Folding endurance proved that the inserts were soft, elastic, and flexible. Chitosan-based ocular inserts showed greater swelling index as compared to gelatin and hydroxypropyl methylcellulose inserts. In vitro studies showed prolonged drug release and followed zero-order kinetic model and non-Fickian drug release.

Research progress of photonics devices on lithium-niobate-on-insulator thin films

&lt;sec&gt; Lithium niobate (LiNbO&lt;sub&gt;3&lt;/sub&gt;, LN) crystals have excellent electro-optical and nonlinear optical properties, and they have been regarded as one of the most promising materials for constructing the multifunctional photonic integrated systems. Due to the excellent optical properties of LN crystal, the emerging LN thin film technology has received great attention in the research of integrated photonics in recent years. With the help of advanced micro-nano fabrication technologies, many high-performance lithium niobate integrated photonic devices have been realized. &lt;/sec&gt;&lt;sec&gt; Integrated photonic platform can incorporate high-density, multi-functional optical components, micro-nano photonics structures, and optical materials on a monolithic substrate, which can flexibly implement a variety of photonic functions. At the same time, it also provides a low-cost, small-size, and scalable solution for miniaturizing and integrating the free-space optical systems. Photonic chips based on LN have been widely used in fast electro-optic modulation, nonlinear optical frequency conversion and frequency comb generation. In particular, periodically poled lithium niobate (PPLN) based on quasi-phase matching has gradually become a mature integrated photonic platform and has been widely used in the field of nonlinear optics.&lt;/sec&gt;&lt;sec&gt; As wafer bonding technology is matured, the lithium-niobate-on-insulator (LNOI) thin films made by the “smart-cut” process have been commercialized. The thickness of the LN film on a Si or SiO&lt;sub&gt;2&lt;/sub&gt; substrate can reach several hundred nanometers, and good uniformity in film thickness at a larger size (3 inches) can be ensured. With the development of micro-nano fabrication technologies, the quality and functions of photonic devices on LNOI chips have been significantly improved in recent years, and research on integrated photonic devices based on LNOI has also been developed rapidly in recent years.&lt;/sec&gt;&lt;sec&gt; In this article we briefly review the development of LNOI technology, introducing the applications of several advanced micro-nano fabrication techniques and summarizing their applications in the micro-/nano-fabrication of on-chip photonic devices based on LNOI wafers. In addition, in this article we also summarize the latest advances in the functionality of LNOI on-chip photonic devices and give a short prospective on their future applications in integrated photonics.&lt;/sec&gt;

Realization and evaluation of the Boron Nano Particle-based drip-coating method for boron-lined gaseous neutron detectors

A variety of boron coating methods have been applied for realizing the boron-lined gaseous neutron detectors, however they usually have to face the problem of non-uniform thickness for large area boron coating and low utilization ratio of boron materials. In this study, a Boron Nano Particle (BNP)-based drip-coating method was researched and introduced, with the advantages of fast boron coating speed and high utilization ratio of boron material. Neutron tests conducted at the Institute Laue Langevin, Grenoble, France, demonstrated that the natB4C sample made by this method can realize boron layer with the mass thickness ranging from 0.05 to 0.5 mg/cm2, as well as a good thickness uniformity, indicating that the BNP-based drip-coating method has the potential to realize boron layers that can be used for various boron-lined gaseous neutron detectors.

Influence of process parameters on deep drawing of 2060 Al–Li alloy under hot stamping process

In this paper, the hot stamping formability of 2060 Al–Li alloy was studied by numerical simulation and experimental tests. The thickness of 2060 Al–Li alloy parts was analyzed when the deformation temperature is 400 °C, 450 °C and 480 °C, stamping speed is 15 mm/s, 25 mm/s and 35 mm/s. Simultaneously, the influence of lubrication on the thinning of 2060 Al–Li alloy cup-shaped parts is also analyzed. And Vickers hardness of the forming parts was tested after hot stamping tests. The results show that the deep drawing parts have good thickness uniformity at the deformation temperature ranging from 400 °C to 450 °C. However, the thickness of the cup parts is thinning seriously when the deformation temperature is 480 °C. With the increase of stamping speed, the thinning rate of cup-shaped parts decreases gradually. In this study, the thinning rate of the drawing parts is smaller when stamping speed is 35 mm/s. Compared with stamping parts without lubrication, cup parts with deeper depth can be obtained under better lubrication. With the improvement of lubrication conditions, the crack position of the formed part gradually shifts to the center of the cup. The simulation results and experimental results have good consistence.

Electrodeposition of Graded Metal Coatings on Spherical Mandrels

Inertial confinement fusion energy research at the National Ignition Facility (NIF) requires the fabrication of hollow metal spherical capsules for the laser-driven fusion reaction. These sub-millimeter diameter capsules must have perfect coating uniformity and a specific gradient density, achieved by plating two metal elements with graded composition. We are investigating electrodeposition to produce hollow metal spheres as opposed to other deposition techniques (i.e. physical vapor deposition, film casting, etc.), because electrodeposition coats faster, more smoothly, with good thickness uniformity, and better grain size control. Electroplating metals on spheres presents its own specific challenges; the spherical samples must make contact with the electrified cathode, but must also remain in motion during plating to ensure an even coating. Additionally, electroplating on hollow spheres also involves the challenge of keeping the sphere submerged in the electrolyte. These issues were mitigated by enclosing the mandrel in an electrified cage which the electrolyte is flowed through, resulting in intermittent contact of the mandrel with the cathode and continuous flow of fresh electrolyte to the mandrel surface while plating. We have developed several approaches for electroplating alloys[1] and density gradients on metal spherical mandrels. We will present results from a parametric study that improved coating uniformity, obtained desired thickness, and achieved the required density gradients during electrodeposition. [1] C. Horwood, M. Stadermann, T.L. Bunn, Metal Alloy ICF Capsules Created by Electrodeposition, Fusion Sci. Technol. 73 (2018) 335–343. doi:10.1080/15361055.2017.1387458. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM Release# LLNL-ABS-748349

High Quality 4H-SiC Epitaxial Layer by Tuning CVD Process

In this work many steps concerning the epitaxial layer growth on 4H-SiC are studied, evaluated and optimized to obtain high quality 4H-SiC epitaxy. The processes evaluated have been studied on a Hot Wall CVD reactor. The first step related to the substrate surface etching has been tuned by choosing the H2 flow, temperature and process time at which most of defects (mainly stacking faults) are not propagated. Then, the buffer layer step has been optimized by increasing the thickness at which an effective reduction of defect density and an improved electrical performance of power devices have been detected. Also, during the buffer layer growth a strong dependence between basal plane dislocations propagation and the growth rate has been observed. A crucial step carefully studied has been the drift layer growth. It was optimized by increasing the growth rate (13&lt;GR&lt;15µm/h) that results in a lower defectiveness, good thickness and doping uniformity. Final stage concerning the cooling of the process has been strongly revisited. A significant decreasing of the morphological defects (carrots, pits) and stacking faults has been observed by slowing the cool down process (~ 25 °C/min).

Batch processing of aluminum nitride by atomic layer deposition from AlCl3 and NH3

Batch processing of aluminum nitride (AlN) by thermal atomic layer deposition (ALD) was studied at high temperatures of 500–550 °C using aluminum chloride (AlCl3) and ammonia (NH3) as metal and nitrogen precursors. The growth behavior, chemical composition, morphology, crystallinity, and residual stress of the AlN films were characterized by ellipsometry, x-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, x-ray diffraction, and the wafer curvature method, respectively. The deposited AlN films at 525 °C had a good batch thickness uniformity of 2.6%, a low surface roughness of ∼1 nm, a low Cl impurity level of ∼1.2%, and a hexagonal polycrystalline structure with a preferential (002) orientation. An obvious dependence between film properties and deposition temperature was found. The evaluation in deposition temperature from 500 to 550 °C resulted in an increase of the growth-per-cycle, refractive index, and tensile stress as well as a decrease of Cl and O impurity levels in the AlN films. Based on these findings, the authors concluded that high quality polycrystalline AlN films with a preferential (002) orientation can be grown with ALD in a large batch reactor at high temperatures (500–550 °C).

Bessel Decomposition of Temperature Profiles in Film Deposition Reactors

Among the three process pillars of adding, patterning, and removing actions in the fabrications of semiconductor devices, film deposition takes up the central position in the construction flow of structure formation. Film uniformity of the deposition processes has significant impacts on the distributions of the electrical functions of the fabricated devices. Achieving good final uniformity of the film thickness depends critically on profiles of the thermal fields inside the film deposition chambers. Constructing simple, efficient, and yet accurate enough models of the temperature fields is therefore crucial in effective fault detection and eventually, for film thickness uniformity controls. Instead of solving systems of nonlinear partial differential field equations or conducting large-scale simulation runs, we explored one decomposition method of the temperature fields using a zeroth order Bessel function of the first kind for applications of fault detection and classification.

Electrodeposition of Graded Metal Coatings on Spherical Mandrels

Inertial confinement fusion energy research at the National Ignition Facility (NIF) requires the fabrication of hollow metal spherical capsules for the laser-driven fusion reaction. These sub-millimeter diameter capsules must have perfect coating uniformity and a specific gradient density, achieved by plating two metal elements with graded composition. We are investigating electrodeposition to produce hollow metal spheres as opposed to other deposition techniques (i.e. physical vapor deposition, film casting, etc.), because electrodeposition coats faster, more smoothly, with good thickness uniformity, and better grain size control. Electroplating metals on spheres presents its own specific challenges; the spherical samples must make contact with the electrified cathode, but must also remain in motion during plating to ensure an even coating. Additionally, electroplating on hollow spheres also involves the challenge of keeping the sphere submerged in the electrolyte. These issues were mitigated by enclosing the mandrel in an electrified cage which the electrolyte is flown through, resulting in intermittent contact of the mandrel with the cathode and a continuous flow of fresh electrolyte to the mandrel surface while plating. We have developed several approaches for electroplating alloys[1] and density gradients on metal spherical mandrels. We will present results from a parametric study that improved coating uniformity, obtained desired thickness, and achieved the required density gradients during electrodeposition. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM Release Number: LLNL-ABS-748349 [1] C. Horwood, M. Stadermann, T.L. Bunn, Metal Alloy ICF Capsules Created by Electrodeposition, Fusion Sci. Technol. 73 (2018) 335–343. doi:10.1080/15361055.2017.1387458.