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Objective Limb salvage is an important concern following complete oncologic resection for extremity soft tissue sarcoma (STS). Vascular reconstruction is essential for limb salvage. The purpose of this study was to evaluate the outcomes of vascular reconstruction in patients with extremity STS. Methods This is a retrospective, multi-center, case series of consecutive patients who underwent vascular reconstruction during extremity STS resection at 2 major centers in Korea. Demographics, reconstruction methods, type of conduit, surgical complications, graft patency, limb salvage rate, and patient survival were reviewed. Results From March 2005 to December 2020, 43 patients underwent vascular reconstructions during STS resection. Among the patients, 22 (51.2%) received arterial only, and 21 (48.8%) received simultaneous arterial and venous reconstructions. For the types of conduits, autologous saphenous veins (56.2%), artificial grafts (26.3%), and cryopreserved allografts (15.8%) were used. During a median follow-up of 23.8 months (interquartile range; 7.7-54.5), the overall primary patency of the reconstructed vessels was significantly higher in arteries than in veins (82.5% vs 56.3% at 12 months, P < .001). According to the type of conduit, the primary patency rate of autogenous vein seemed higher in venous reconstruction, however, there was no statistical significance in both arterial and venous reconstruction. There was no significant difference in primary arterial patency rate ( P = .132) or incidence of surgical complications including postoperative edema or wound problem whether or not simultaneous venous reconstruction was performed with arterial reconstruction. The overall limb salvage rate and patient survival were 97.4%, 95.1%, and 89.4% and 91.9%, 81.7%, and 65.4% at 12, 24, and 36 months, respectively. Conclusions Patency rates were poorer in venous reconstruction than in arterial reconstruction. In terms of arterial patency and postoperative complication, the role of simultaneous arterial and venous reconstruction seems not essential, however, it needs to be evaluated in future studies.

Objectives: The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guidelines recommend forearm arteriovenous grafts (AVGs) as an alternative procedure to transposed basilic vein fistulas for providing secondary access during hemodialysis. Recently, autogenous elevated brachial-brachial vein fistulas (BVE) have become increasingly popular. The aim of this study was to compare the outcomes of BVE and forearm loop AVG (AVG) for secondary access in hemodialysis. Methods: We retrospectively reviewed the medical records of patients who had received a BVE or forearm AVG at a single center from January 2015 to April 2019. In total, 19 BVE were created via two-stage operations and two via a one-stage operation; 53 forearm AVG’s were performed. Results: The AVG group was twice as likely to suffer loss of primary patency compared with the BVE group (odds ratio [OR], 2.666; 95% confidence interval [CI], 1.108–6.412; p = 0.029) per the multivariate analysis. The primary patency and primary assisted patency of the BVE group were superior those of the AVG group, except for secondary patency ( p = 0.02, p = 0.07, p = 0.879, respectively). In subgroup analysis, there were no significant differences in primary, primary assisted, or secondary patency between AVG and BVE when brachial vein was used for AVG outflow. In addition, no significant differences were noted regarding the infection rate (12.5% vs 12.3%, p = 0.331, severity >0), postoperative bleeding rate (14.5% vs 3.5%, p = 0.191, severity >1), early thrombus rate (0.0% vs 10.5%, p = 0.122), and early failure rate (7% vs 4.8%, p = 0.591). Conclusions: The primary patency and primary assisted patency rates of BVE were significantly better than those observed in AVGs, but the complication rates were similar. The appropriate procedure to provide vascular access should be determined by the individual patient’s condition and the surgical skill of the operating surgeon.

Introduction Single-port laparoscopic appendectomy (SPLA) was expected to have reduced risk of wound infection, less postoperative pain, and improved patient's satisfaction with better cosmesis compared with conventional laparoscopic appendectomy (CLA). When SPLA is converted to CLA, the additional incision for another port insertion can lead to a decrease in the surgical advantages and clinical benefit. Aim To evaluate risk factors for conversion to CLA during SPLA. Material and methods Between August 2015 and December 2016, patients who underwent intended SPLA were retrospectively reviewed. Conversion was defined as any insertion of an additional port, and complicated appendicitis was defined as gangrenous or perforated appendicitis, abscess, or peritonitis in preoperative computed tomography. Postoperative complication was defined as any deviation in the routine postoperative course within 30 days postoperatively. Results Of 409 patients, 65 (15.9%) were treated with additional port insertion. The overall complication rate was 1.5% in each group, of which 1 patient developed superficial SSI and 4 patients developed deep surgical site infections in the SPLA group. After univariable and multivariable analysis, old age, male sex, increased serum C-reactive protein (OR = 2.944; 95% CI: 1.433-6.047; p = 0.003), and complicated appendicitis (OR = 3.330; 95% CI: 1.304-8.503; p = 0.012) were significant risk factors for conversion to CLA. Conclusions The conversion rate to CLA was 15.9%. Serum C-reactive protein level and complicated appendicitis were strong predictive factors for conversion from SPLA in acute appendicitis.

A soft-contact film transfer method was developed to prepare multilayer photoresist thin films that enable high-resolution spectroscopic and reflectivity measurements for determining the reaction−diffusion kinetic parameters and photoacid diffusion length. Infrared reflectance absorption spectroscopy was applied to follow, quantitatively, the reaction−diffusion kinetics during the post-exposure bake (PEB) step; the time evolution of the average deprotection level across a bilayer film with model photoresists is described by a kinetics model with three parameters: a reaction rate constant (kP), the phenomenological photoacid trapping constant (kT), and the photoacid diffusion constant (DH). A polymeric and molecular resist for next-generation extreme ultraviolet (EUV) lithography with chemically analogous structure was studied with this methodology. The three kinetic parameters follow an Arrhenius dependence but show quantitative differences between these two photoresists at a given PEB temperature. Furthe...

The photopolymerization kinetics of typical dental dimethacrylate monomers were studied by differential photocalorimetry. Increasing proportions of the low-viscosity diluent monomer triethylene glycol dimethacrylate (TEGDMA) were added to either Bis-GMA (2,2-bis[p-(2‘-hydroxy-3‘-methacryloxypropoxy)phenylene]propane), EBADMA (ethoxylated bisphenol A dimethacrylate), or UDMA (1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimethylhexane) to provide three base resins that differed in their hydrogen-bonding potential and, therefore, resulted in compositions covering a broad range of viscosities. When compared at similar diluent concentrations, UDMA resins were significantly more reactive than Bis-GMA and EBADMA resins. At higher diluent concentrations, EBADMA resins provided the lowest photopolymerization reactivities. Optimum reactivities in the UDMA and EBADMA resin systems were obtained with the addition of relatively small amounts of TEGDMA, whereas the Bis-GMA/TEGDMA resin system required near equiv...

As the demand of the rechargeable battery has been requested not only from operating the small devices, but also from operating the large and medium size equipment such as an electric vehicle, the research has been focused on the stability of the battery, minimization of the energy loss, and finding the new materials for effective energy storage. The Lithium-ion (Li-ion) battery consists of four main components which are cathode active material, anode active material, electrolyte, and the separator. One of current research fields of the Li-ion battery material is in the area of cathode active material. It is because the cathode active material has 30∼40% of the manufacturing cost and it vastly affects the capacity of the batteries. In this research, we conduct one-cell simulation to compare the battery performance for changing the properties of the Cathode material. It is one of the thermochemical parameters that can affect the charge/discharge rate and the life of the batteries. Although, the certain kind of active materials has been reported in previous reports, we used the new material properties and researched about the whole discharge curve for future material development. The heating behavior is also investigated with the arbitrary properties being varied.Copyright © 2012 by ASME

The photoacid diffusion length is a critical issue for extreme ultraviolet (EUV) lithography because it governs the critical dimension (CD), line-edge-roughness (LER), and line-width-roughness (LWR) of photoresist materials. Laboratorybased experimental methods that complement full lithographic testing would enable a rapid screening of materials and process conditions. This paper provides an approach to characterize the photoacid diffusion length by applying a bilayer stack technique. The method involves quantitative measurements of the deprotection kinetics as well as film thickness at each process step: radiation exposure, post-exposure bake, and development. Analogous to a contrast curve, by comparing the film thickness of the bilayer before and after development, the photoacid diffusion length was deduced in a commercial EUV photoresist and compared to EUV lithography. Further, by combining the experiments with kinetics modeling, the measured photoacid diffusion length was predicted. Lastly, based upon the measured kinetics parameters, a criterion was developed that next-generation resists must meet to achieve a 16 nm photoacid diffusion length. These guidelines are discussed in terms of correlations and contributions from the photoacid and resist properties. In particular, the trapping kinetics of the photoacid provides a route to reduce LER and the CD at low dose.

Non-planar transistor architectures, such as tri-gates or "FinFETs", have evolved into important solutions to the severe challenges emerging in thermal and power efficiency requirements at the sub-32 nm technology nodes. These architectures strain traditional dimensional metrology solutions due to their complex topology, small dimensions, and number of materials. In this study, measurements of the average dielectric layer thickness are reported for a series of structures that mimic non-planar architectures. The structures are line/space patterns (≈ 20 nm linewidth) with a conformal layer of sub-15 nm thick high-k dielectric. Dimensions are measured using a transmission X-ray scattering technique, critical dimension small angle X-ray scattering (CD-SAXS). Our test results indicate that CD-SAXS can provide high precision dimensional data on average CD, pitch, and high-k dielectric layer thickness. CD-SAXS results are compared with analogous data from both top-down scanning electron microscopy and cross-sectional transmission electron microscopy. In addition, we demonstrate the capability of CD-SAXS to quantify a periodic deviation in pitch induced by an imperfection in the phase shift mask.

Critical dimension small angle X-ray scattering (CD- SAXS) is a metrology platform that is capable of measuring the average cross section and linewidth roughness (LWR) in test patterns with pitches ranging from 10 to 500 nm with sub-nm precision. These capabilities are obtained by measuring and modeling the scattering intensities of a collimated X-ray beam with sub-nm wavelength from a periodic pattern, such as those found in optical scatterometry targets. In this work, we evaluated the capability of both synchrotron-based and laboratory-scale CD-SAXS for characterizing LWR from measurements of periodic line/space patterns fabricated with extreme ultraviolet (EUV) lithography with sub-50 nm linewidths and designed with programmed roughness amplitude and frequency. For these patterns, CD-SAXS can provide high precision data on cross section dimension, including sidewall angle, line height, linewidth and pitch, as well as the amplitude of LWR. We will also discuss the status of ongoing efforts to compare quantitatively the CD- SAXS data with top-down scanning electron microscopy (CD- SEM) measurements.

Critical dimension small angle X-ray scattering (CD-SAXS) is a measurement platform that is capable of measuring the average cross section and sidewall roughness in patterns ranging from (10 to 500) nm in pitch with sub-nm precision. These capabilities are obtained by measuring and modeling the scattering intensities of a collimated X-ray beam with sub-nanometer wavelength from a periodic pattern, such as those found in optical scatterometry targets. In this work, we evaluated the capability a synchrotron-based CD-SAXS measurements to characterize linewidth roughness (LWR) by measuring periodic line/space patterns fabricated with extreme ultraviolet (EUV) lithography with sub-50 nm linewidths and designed with programmed roughness amplitude and frequency. For these patterns, CD-SAXS can provide high precision data on cross-section dimensions, including sidewall angle, line height, line width, and pitch, as well as the LWR amplitude. We also discuss the status of ongoing efforts to compare quantitatively the CD-SAXS data with topdown critical dimension scanning electron microscopy (CD-SEM) measurements.

The photon-stimulated emission of organic molecules from the photoresist during exposure is a serious problem for extreme-ultraviolet lithography (EUVL) because the adsorption of the outgassing products on the EUV optics can lead to carbonization and subsequent reflectivity loss. In order to accurately quantify the total amount of outgassing for a given resist during an exposure, we have constructed a compact, portable chamber that is instrumented with a spinning rotor gauge and a capacitance diaphragm gauge that, unlike the more commonly used ionization gauge or quadrupole mass spectrometer, provides a direct and accurate measurement of the total pressure that is largely independent of the composition of the outgas products. We have also developed a method to perform compositional analysis on the outgas products and, more generally, on any contaminants that might be present in the stepper vacuum. The method involves collecting the vacuum contaminants in a trap cooled to liquid-nitrogen temperature. Once collected, the products from the trap are transferred to a system for analysis with gas chromatography with mass spectrometry. We will describe the workings of the instruments in detail as well as results of initial tests.

Current extreme ultraviolet (EUV) photoresist materials do not yet meet performance requirements on exposure-dose sensitivity, line-width roughness, and resolution. In order to quantify how these trade-offs are related to the materials properties of the resist and processing conditions, advanced measurements and fundamental studies are required that consider EUV-resist specific problems. In this paper, we focus on the correlations between the latent image and developed image in EUV exposed line/space features. The latent images of isolated lines produced by EUV lithography are characterized by atomic force microscopy through the change in topology caused by change in film thickness that occurs upon deprotection. The resulting latent-image deprotection gradient (DGL), based on line cross-sections, and latent-image line-width roughness (LWRL) provide metrics and insight into ways to optimize the lithographic process. The results from a model poly(hydroxystyrene-co-tert-butylacrylate) resist and a model calix[4]resorcinarene molecular glass type resist show the general applicability of the metric before development.

Critical dimension small angle X-ray scattering (CD-SAXS) is a metrology platform capable of measuring the average cross section and line width roughness (LWR) with a sub-nm precision in test patterns with line widths ranging from 10 to 500 nm. The X-ray diffraction intensities from a collimated X-ray beam of sub-Angstrom wavelength were collected and analyzed to determine line width, pitch, sidewall angle, LWR, and others structural parameters. The capabilities of lab-scale and synchrotron-based CD-SAXS tools for LWR characterization were tested by measuring a set of identical patterns with designed roughness amplitude and frequency. These test patterns were fabricated using EUV lithography with sub-50 nm linewidths. To compensate for the limited photon flux from the lab-based X-ray source, the incident beam of the lab system was collimated to a less extent than the synchrotron beam-based tool. Consequently, additional desmearing is needed to extract information from data obtained from lab-based equipment. We report the weighted nonlinear least-squares algorithm developed for this purpose, in addiiton to a comparison between the results obtained from our lab system and the synchrotron beam-based tool.

It has been recently postulated that sub-22 nm photolithography with polymeric photoresists has reached a materials design barrier due to its large molecular mass and distribution. In this argument, the "pixel" size, which is related to the smallest molecular unit, determines the feature fidelity and resolution of the lithographic process. This hypothesis remains unproven, but molecular glass photoresists can provide a test because they can share similar chemical functionality to polymer resists, but with low molecular mass and a monodisperse molecular mass distribution. The low molecular mass leads to the smaller pixel size compared to the radius of gyration of the polymer photoresist. In this work, we compare the deprotection reaction-diffusion kinetics of a common photoacid generator in a polymer and molecular glass resist with similar resist chemistry to elucidate effects of molecular architecture on photoresist performance. We determine the mechanism of reaction, photoacid trapping behavior, and diffusivity by measuring and comparing the reaction kinetics parameters as a function of temperature and exposure dose. These results permit an analysis of the latent image formation which is a crucial factor in resolution and line-edge roughness. Further, knowledge of the reaction-diffusion parameters of each type of resist provides a quantitative approach to predict line-space features, crucial for design for resolution-enhancement features.

Current extreme ultraviolet (EUV) photoresist materials do not yet meet requirements on exposure-dose sensitivity, line-width roughness (LWR), and resolution. Fundamental studies are required to quantify the trade-offs in materials properties and processing steps for EUV photoresist specific problems such as high photoacid generator (PAG) loadings and the use of very thin films. Furthermore, new processing strategies such as changes in the developer strength and composition may enable increased resolution. In this work, model photoresists are used to investigate the influence of photoacid generator loading and developer strength on EUV lithographically printed images. Measurements of line width roughness and developed line-space patterns were performed and highlight a combined PAG loading and developer strength dependence that reduce LWR in a non-optimized photoresist.

The need to characterize line edge and line width roughness in patterns with sub-50 nm critical dimension challenges existing platforms based on electron microscopy and optical scatterometry. The development of x-ray based metrology platforms provides a potential route to characterize a variety of parameters related to line edge roughness by analyzing the diffracted intensity from a periodic array of test patterns. In this study, data from a series of photoresist line/space patterns featuring programmed line width roughness measured by critical dimension small angle x-ray scattering (CDSAXS) is presented. For samples with periodic roughness, CD-SAXS provides the wavelength and amplitude of the periodic roughness through satellite diffraction peaks. In addition, the rate of decay of intensity, termed an effective "Debye-Waller" factor, as a function of scattering vector provides a measure of the fluctuation in line volume. CDSAXS data are compared to analogous values obtained from critical dimension scanning electron microscopy (CDSEM). Correlations between the techniques exist, however significant differences are observed for the current samples. Calibrated atomic force microscopy (C-AFM) data reveal large fluctuations in both line height and line width, providing a potential explanation for the observed disparity between CD-SEM and CD-SAXS.

The need to characterize line edge and line width roughness in patterns with sub‐50 nm critical dimensions challenges existing platforms based on electron microscopy and optical scatterometry. The development of x‐ray based metrology platforms provides a potential route to characterize a variety of parameters related to line edge roughness by analyzing the diffracted intensity from a periodic array of test patterns. In this study, data from a series of photoresist line/space patterns featuring programmed line width roughness are measured by critical dimension small angle x‐ray scattering (CD‐SAXS). For samples with designed periodic roughness, CD‐SAXS provides the wavelength and amplitude of the periodic roughness through satellite diffraction peaks. For real world applications, the rate of decay of intensity, termed an effective “Debye‐Waller” factor in CD‐SAXS, provides an overall measure of the defects of the patterns. CD‐SAXS data are compared to values obtained from critical dimension scanning electron microscopy (CD‐SEM). Correlations between the techniques exist, however significant differences are observed for the current samples. A tapered cross sectional profile provides a likely explanation for the observed differences between CD‐SEM and CD‐SAXS measurements.

Chemical force microscopy, a variant of atomic force microscopy, is being developed to image the spatial distributions of chemical species at different stages of the lithography process. By imaging the chemical changes that occur in the resist during the lithographic process we gain insight into the fundamental physical and chemical processes that determine the fidelity of pattern replication in the resist. We have examined several stages of the lithography process including the homogeneity of resist after spin casting, latent image formation, and segregation during development to look for possible contributions to line width roughness in lithographic patterns. We have obtained good chemical contrast in a variety of systems that provide insight into the underlying fundamentals. We also discuss work to develop the metro logical underpinnings of chemical force microscopy.

More demanding requirements are being made of photoresist materials for fabrication of nanostructures as the feature critical dimensions (CD) decrease. For extreme ultraviolet (EUV) resists, control of line width roughness (LWR) and high resist sensitivity are key requirements for their success. The observed LWR and CD values result from many factors in interdependent processing steps. One of these factors is the deprotection interface formed during the post-exposure bake (PEB) step. We use model EUV photoresist polymers to systematically address the influence of exposure-dose on the spatial evolution of the deprotection reaction at a model line edge for fixed PEB time using neutron reflectivity. The bilayer consists of an acid feeder layer containing photoacid generator (PAG) and a model photoresist polymer, poly(hydroxystyrene-co-tert-butylacrylate) with perdeuterated t-butyl protecting group. The deuterium labeling allows the protection profile to be measured with nanometer resolution. The evolution of two length scales that contribute to the compositional profile is discussed.

We are developing a transmission X-ray scattering platform capable of measuring the average cross section and line edge roughness in patterns ranging from 10 nm to 500 nm in width with sub-nm precision. Critical Dimension Small Angle X-ray Scattering (CD-SAXS) measures the diffraction of a collimated X-ray beam with sub-Angstrom wavelength from a repeating pattern, such as those in light scatterometry targets, to determine the pattern periodicity, line width, line height, and sidewall angle. Here, we present results from CD-SAXS with an emphasis on line edge roughness characterization. Line edge roughness measurements from CD-SAXS are compared with top-down scanning electron microscopy values and comparative definitions are discussed.

A combination of specular and off-specular neutron reflectometries was used to measure the buried lateral roughness of the reaction-diffusion front in a model extreme ultraviolet lithography photoresist. Compositional heterogeneities at the latent reaction-diffusion front has been proposed as a major cause of line edge roughness in photolithographic features. This work describes the experimental observation of the longitudinal and lateral compositional heterogeneities of a latent image, revealing the buried lateral length scale as well as the amplitude of inhomogeneity at the reaction-diffusion front. These measurements aid in determining the origins of line edge roughness formation, while exploring the material limits of the current chemically amplified photoresists.

The effect of exposure dose on the latent image deprotection profile in a model extreme ultraviolet (EUV) photoresist polymer, poly(hydroxystyrene-co-d9-tert-butyl acrylate), is measured with neutron reflectometry. As the photoacid concentration is increased by exposure dose, the spatial extent of propagation increases but eventually becomes self-limited by the products of the reaction. A long-range deprotection path occurs with diffusion length between 10 and 100A, while an additional subnanometer short-range deprotection length scale proceeds monotonically with dose. These measurements show that the photoacid diffusion length into unexposed regions of a photoresist is limited even in the absence of base quencher additives. These fundamental data can be used to highlight materials effects on photoresist processing and to improve quantitative models for EUV photoresists needed at the sub-32‐nm half pitch lithography.