Silylation and dry procession

The issues of dry development and self-developing resists are addressed in this paper by way of an introduction to the main topic of surface imaging, in which diffusion-enhanced vapour plhase silylation chemistries and their mechanisms are developed with specific reference to resists that function through the DESIRE process. More recent liquid phase silylation processes are also considered.     

Novel approach to simulation of the silylation bake in the DESIRE process

This contribution presents a simple quantitative model — the reaction dominated propagation model — for the simulation of the silylation bake in the DESIRE process. This allows to do very effectively simulation of three dimensional silylated resist patterns. The model is discussed and resist calibration is demonstrated for the i-line resist PLASMASK 206-I from JSR-Electronics     

Sensitivity-enhanced dry development process for VUV and EUV lithography using graft-polymerization

The proposed dry development process uses the graft-polymerization of Si-containing monomers to silylate the resist surface, thus enhancing oxygen plasma etching durability. Single-layer and negative-tone resist patterns can thus be delineated with very high sensitivity. Grafting sensitivity higher than that of wet-developed chemical-amplification resist is obtained by using a Si-containing monomer having acrylic acid ester. This is confirmed through experiments using PMMA as the resist, 3-acryloxypropylmethyldimethoxysilane (APMS) as the monomer, and a laser-plasma X-ray source for exposure. The dry-etching durability of PMMA grafted using APMS is about four times that of ungrafted PMMA. FT-IR measurements show that this is due to the resist-surface silylation caused by the grafting. These results indicate the applicability of this process to VUV and EUV lithographies.     

Repair of plasma-damaged p-SiOCH dielectric films in supercritical CO2

The silylation of plasma-damaged p-SiOCH low-k dielectric films was investigated with trimethychlorosilane (TMCS), hexamethyldisilazane (HMDS) and dimethyldichlorosilane (DMDCS) dissolved in supercritical CO₂ (scCO₂) and the effect of thermal pre-treatment on the repair performance was also studied. The surface hydrophobicity was rapidly recovered by silylation and the order of recovery efficiency was HMDS (85.4°) > DMDCS (83.4°) > TMCS (75.0°). The FTIR analyses revealed that the restoration to the original state was not achieved over various reaction conditions (up to 31 MPa, 85 °C, and 3 h reaction time). After pre-treatment in a vacuum cell at 250 °C, the Si-O-Si peak intensity increased slightly, and the surface hydrophobicity was partially recovered to 54.4° due to the removal of physically adsorbed H₂O molecules as well as some extent of dehydration of neighboring surface silanol groups. The hydrophobicity increased to 84.4° after subsequent treatment with HMDS in scCO₂. From DSIMS, the carbon concentration did not increase in bulk region after silylation of thermally pre-treated low-k films.     

A case study of statistical process control on the prime process using PLASMASK 302U

In this paper, Statistical Process Control (SPC) and statistically designed experiments will be used to optimise a recently developed resist schemes i.e., PRIME (Positive Resist Image by dry Etching). Orthogonal experiments are designed and conducted in order to produce 0.2 μm lines repeatably in PLASMASK 302U resist. Design rules of 0.1 μm are used due to proximity effects. The data is then explored and analysed using surface plots, boxplots, analysis of variance (ANOVA) and linear regression. It was deduced that e-beam dose and 2nd step etch time were the most significant parameters in the process. Linewidth of 0.2 gm and below were achieved with low values of e-beam dose (250–350μC/cm²) and high values of silylation temperature (205–215°C). The optimum range for NUV flood dose was easily found.     

Broad-band extreme ultraviolet lithography with a wet-silylated and dry-developed resist

Broad-band extreme ultraviolet (1340nm) lithography (EUVL) has been examined. Exposure intensity at the broad-band of 1340nm was 20 times larger than at the conventional narrow-band of 13nm. Moreover, broad-band EUVL with a wet-silylated and dry-developed resist process has been investigated in order to obtain a high resolution of 0.1μm with high-aspect-ratio. Imaging experiments were performed using 32:1 reduction Schwarzschild optics illuminated with a synchrotron radiation light source from SORTEC ring. The exposure was done through a 0.1μm-thick SiN vacuum window, Mo/Si multilayer coated optics and without a Be filter. Silylation characterization and determination of optimum composition of the silylation solution have been performed using Fourier transform infrared spectroscopy (FTIR). Using broad band EUVL with the optimal wet-silylated and dry-developed resist, 0.1μm lines and spaces of 0.55μm-thick resist (aspect RATIO = 5.5) can be successfully delineated.     

Hierarchically Porous Bio-Based Sustainable Conjugate Sponge for Highly Selective Oil/Organic Solvent Absorption

This paper describes a novel conjugate biodegradable sponge based on the tree gum kondagogu with excellent selective oil/organic solvent absorption ability. The conjugate sponge is made hydrophobic (water contact angle 133°) by post-process vapor phase silylation, has porosity of ≈94% with very low density (18.4 mg cm⁻³). The sponge can absorb selectively up to 19–43 times its weight of oils and organic solvents. Meanwhile, good reusability is also observed in up to at least 10 cycles. The biodegradation behavior is studied from BOD (biological oxygen demand) analysis, where the non-silylated and silylated sponges degraded over 28 days by 92% and 76%, respectively, in waste-water sludge. The novel conjugate bio-based and biodegradable sponge used in this study is a promising sustainable material for clearing oil spills and for water treatment.     

常压制备SiO2气凝胶薄膜

采用溶胶-凝胶工艺在常压下制备了SiO2气凝胶薄膜,并用傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)、椭偏光谱仪等表征了薄膜的结构和性能.研究结果表明,气凝胶薄膜的折射率低达1.067,对应孔洞率为87.7%,密度为0.269×103kg·m-3,热导率为0.020W·m-1·K-1(300K)时,介电常数为1.52.这些优异性能的获得,主要归因于酸/碱两步催化、溶剂替换以及胶粒表面硅烷化等三个过程.     

激光诱导热解碳表面微结构及抗凝血性研究

为了研究材料表面微结构对其抗凝血性能的影响,利用纳秒激光在人工心脏瓣膜材料热解碳的表面进行微加工的方法,产生了具有周期性的微坑、微光栅阵列结构。通过扫描电镜、X射线衍射仪和接触角测量仪对样品结构、表面成分、表面能进行表征,并测试了改性后热解碳表面的抗凝血性。结果表明,激光加工后的微结构表面和光滑表面化学成分相同,且微结构表面具有超疏水性,表面能很小;与光滑表面相比,微结构表面粘附较少的血小板,而且较少团簇及变形,表现出较好的抗凝血性能。这一结果对人工心脏瓣膜进行表面改性以提高其抗血栓性能具有很大的帮助。     

Pure‐Silica‐Zeolite MFI and MEL Low‐Dielectric‐Constant Films with Fluoro‐Organic Functionalization

The synthesis of organic‐functionalized pure‐silica‐zeolites (PSZs) with MFI‐ and MEL‐type structures for low‐k applications prepared through a direct‐synthesis method by adding a fluorinated silane to the synthesis solution is reported. The added fluorine functionality increases the hydrophobicity of the zeolites, which are characterized by scanning electron microscopy, X‐ray diffraction, ²⁹Si and ¹⁹F solid‐state NMR spectroscopy, nitrogen adsorption, and thermogravimetric analysis. The functionalized zeolite powders have low water content and calcined spin‐on films prepared from the functionalized nanoparticle suspensions exhibit higher water contact angles and lower k values (2.1 and 1.8 for the functionalized MFI‐ and MEL‐type zeolites, respectively) than PSZ films. The use of a direct‐synthesis method to decrease the moisture adsorption in the films eliminates the extra post‐spin‐on silylation steps that are traditionally used to render the zeolite films hydrophobic.     

Polysiloxane Cross-Linked Mechanically Stable MXene-Based Lithium Host for Ultrastable Lithium Metal Anodes with Ultrahigh Current Densities and Capacities

The applications of lithium metal anode are limited by uncontrollable lithium dendrite growth and infinite volume changes during cycling. These fundamental issues are exacerbated at high cycling current densities and capacities. Herein, a mechanically stable and resilient lithium metal host is fabricated by covalently cross-linking a highly-conductive and lithiophilic MXene/silver nanowire scaffold through a silylation reaction between MXene nanosheets and polysiloxane. Compared with the control sample (an MXene scaffold assembled by weak van der Waals forces), the covalently cross-linked MXene scaffold displays excellent mechanical strength and resilience, which is conducive to buffer the large internal stress fluctuations generated during rapid and deep lithium plating-stripping and guaranteed that the integrated framework structure is maintained during long-term charging-discharging cycles. When used in a symmetric cell, the lithium composite anode based on the covalently cross-linked MXene host affords an unprecedented cyclic lithium plating-stripping stability of a record-high 3000 h lifespan at an ultrahigh current density (20 mA cm⁻²) and areal capacity (10 mAh cm⁻²). When this composite anode is coupled with a LiNi_0.5Co_0.2Mn_0.3O₂ cathode, the full cell delivers an ultrahigh rate of 10 C for up to 1000 cycles, with an average capacity decay of 0.043% per cycle and a stable Coulombic efficiency of 98.7%.     

Highly Fluorescent Mesostructured Films that consist of Oligo(phenylenevinylene)–Silica Hybrid Frameworks

Highly fluorescent and visible‐light‐responsive mesostructured organosilica films are successfully obtained by acidic sol–gel polycondensation of oligo(phenylenevinylene) (OPV)‐bridged organosilane and tetraethoxysilane precursors in the presence of a template surfactant. The OPV‐bridged organosilane precursors with different lateral alkoxy substituents, hexyloxy and 2‐ethylhexyloxy, and no substituent, are synthesized by Rh‐catalyzed silylation of corresponding aromatic iodides. From the organosilane precursors, three kinds of mesostructured OPV–silica hybrid films are prepared by spin‐casting using evaporation‐induced self‐assembly. UV‐vis absorption and fluorescence behavior of the OPV–silica hybrid films show that the optical properties and intermolecular interactions of the OPV moieties embedded within the organosilica frameworks strongly depend on the lateral alkoxy substituents in the precursors. The hexyloxy and 2‐ethylhexyloxy substituents prevent aggregation of the OPV units in the organosilica frameworks; this result leads to high fluorescence quantum yields of 0.48–0.61 and 0.63–0.66, respectively, while non‐substitution leads to lower fluorescence quantum yields of 0.25–0.34. Fluorescence decay profiles of the organosilica hybrid films also confirm a suppression of the aggregation of OPV moieties by the lateral substituents. These mesostructured organosilica films with significant optical properties in the visible‐light region are promising as a new class of phosphor materials.     

Single Step Preparation of Novel Hydrophobic Composite Films for Low‐k Applications

Composite films with low dielectric constants (k) containing micro‐ and mesopores are synthesized from precursor solutions for the preparation of mesoporous silica and ethanolic suspensions of silicalite‐1 nanoparticles. The material contains silicalite‐1 nanoparticles (include nanocrystals and nanoslabs/intermediates) embedded in a randomly oriented matrix of highly porous mesoporous silica. Micropores result from the incorporated silicalite‐1 nanoparticles, while decomposition of the porogen F127 leads to additional mesopores. The porosity of the composite films increases from 9 to 60% with the increase in porogen loading, while in parallel the elastic modulus and hardness decrease. The elastic moduli of the films are in the range of 13–20 GPa. Hydrophobic surfaces of the composite films are obtained by introducing methyl triethoxysilane during the preparation of both precursor solutions, leading to the incorporation of ? CH₃ groups in the final composite films. These methyl groups are stable up to at least 500 °C. A low k value of approximately 2 is observed for films cured at 400 °C in N₂ flow, which is ideal for removing templates without decomposing methyl groups. Due to the intrinsic hydrophobicity of the material, post‐silylation is not required rendering the composite films attractive candidates for future low k materials.     

Ordered Mesoporous Silica Derived from Layered Silicates

Here, the development of ordered mesoporous silica prepared by the reaction of layered silicates with organoammonium surfactants is reviewed. The specific features of mesoporous silica are discussed with relation to the probable formation mechanisms. The recent understanding of the unusual structural changes from the 2D structure to periodic 3D mesostructures is presented. The formation of mesophase silicates from layered silicates with single silicate sheets depends on combined factors including the reactivity of layered silicates, the presence of layered intermediates, the variation of the silicate sheets, and the assemblies of surfactant molecules in the interlayer spaces. FSM‐16‐type (p6mm) mesoporous silica is formed via layered intermediates composed of fragmented silicate sheets and alkyltrimethylammonium (C_nTMA) cations. KSW‐2‐type (c2mm) mesoporous silica can be prepared through the bending of the individual silicate sheets with intralayer and interlayer condensation. Although the structure of the silicate sheets changes during the reactions with C_nTMA cations in a complex manner, the structural units caused by kanemite in the frameworks are retained. Recent development of the structural design in the silicate framework is very important for obtaining KSW‐2‐based mesoporous silica with molecularly ordered frameworks. The structural units originating from layered silicates are chemically designed and structurally stabilized by direct silylation of as‐synthesized KSW‐2. Some proposed applications using these mesoporous silica are also summarized with some remarks on the uniqueness of the use of layered silicates by comparison with MCM‐type mesoporous silica.     

Synthesis and Optoelectronic Properties of Nonpolar Polyrotaxane Insulated Molecular Wires with High Solubility in Organic Solvents

Hydrophilic polyanionic conjugated polyrotaxanes are readily synthesized in water by Suzuki coupling, but their high polarity and ionic nature limit the potential applications of these materials. Here, we demonstrate three methods for transforming these polar polyelectrolytes into nonpolar lipophilic insulated molecular wires. A water‐soluble polyfluorene‐alt‐biphenylene β‐cyclodextrin (CD) polyrotaxane was converted into nonpolar derivatives by methylation of the carboxylic acid groups with diazomethane and conversion of the hydroxyl groups of the CDs to benzyl ethers, trihexylsilyl ethers, benzoyl esters, and butanoate esters to yield polyrotaxanes that are soluble in organic solvents such as chloroform and cyclohexane. Elemental analysis, NMR spectroscopy, and gel permeation chromatography (GPC) data support the proposed structures of the organic‐soluble polyrotaxanes. The extents of reaction of the polyrotaxane CD hydroxyl groups were 55% for trihexylsilyl chloride/imidazole; 81% for benzyl chloride/sodium hydride; 72% for benzoyl chloride/pyridine/4‐dimethylaminopyridine; and 98% butanoic anhydride/pyridine/4‐dimethylaminopyridine. Alkylation, silylation, and esterification increase the bulk of the encapsulating sheath, preventing interstrand aggregation, increasing the photoluminescence efficiency in the solid state and simplifying the time‐resolved fluorescence decay. The organic‐soluble polyrotaxanes were processed into polymer light‐emitting diodes (PLEDs) from solution in nonpolar organic solvents, thereby excluding ionic impurities from the active layer.     

Run by run process control: combining SPC and feedback control

The run by run controller provides a framework for controlling a process which is subject to disturbances such as shifts and drifts as a normal part of its operation. The run by run controller combines the advantages of both statistical process control (SPC) and feedback control. It has three components: rapid mode, gradual mode, and generalized SPC. Rapid mode adapts to sudden shifts in the process such as those caused by maintenance operations. Gradual mode adapts to gradual drifts in the process such as those caused by build-up of deposition inside a reactor. The choice between the two modes is determined by the outcome from generalized SPC which allows SPC to be applied to a process while it is being tuned. The run by run controller has been applied to the control of a silicon epitaxy process in a barrel reactor. Rapid mode recovered the process within 3 runs after a disturbance. Gradual mode reduced the variation of the process by a factor of 2.7 as compared to historical data     

砷化镓0.5 μm PHEMT开关标准工艺研究

采用PCM技术对砷化镓0.5μmPHEMT开关工艺关键工艺步骤进行定量严格监控,并对关键工艺节点进行工序能力评价(Cpk),运用统计过程控制(SPC)技术对采集的工艺数据进行分析,实现了开关工艺的稳定受控,工艺水平不断提高,砷化镓单片开关的成品率逐步提升;同时采用REM技术对该工艺制作的PHEMT开关器件、无源元件进行可靠性的预先估计,实现了对该标准工艺的可靠性评估。研究数据表明,砷化镓0.5μmPHEMT开关标准工艺PCM成品率达到90%,开发的单片开关和衰减器成品率不低于80%;砷化镓单片开关在最高工作温度85°C、置信度90%下失效率λ小于400Fit,完全满足产品的使用要求。     

Joint quantisation and error diffusion of colour images usingcompetitive learning

A competitive learning scheme for colour image quantisation is elaborated, in which the dithering process to eliminate contouring effects is embedded in the quantisation process instead of performed a posteriori. Quantisation is performed by clustering in colour space. The dithering process is a simple error diffusion, in which the quantisation error made by one pixel is diffused to its local neighbourhood. An objective function which takes the dithering process into account is optimised by use of a competitive learning approach. In this way, the colour quantisation process is optimally adapted to the dithered image, and the dithering process is optimally adapted to the colour palette. For small colour palettes, this is demonstrated to improve the visual quality of quantised images     

基于半马尔科夫过程的变压器故障率预测及研究

设备的故障率曲线是制定维修策略的重要指标之一。为了合理估计变压器的故障率,本文提出了基于半马尔科夫过程的预测模型。模型中考虑了变压器的热老化过程和随机故障过程。热老化过程根据绝缘纸平均聚合度的取值范围划分为4个状态,状态间的转移时间假设服从威布尔分布,威布尔分布的尺度参数由经验公式获得;随机故障过程考虑了由雷击和短路冲击引起的2个随机故障状态,老化状态和随机故障状态之间的转移时间假设服从指数分布,转移率由故障统计数据获得。对模型中威布尔分布的形状参数进行适当取值后,可获得符合实际统计结果的变压器故障率曲线。     

An EM Algorithm for Markov Modulated Markov Processes

An expectation–maximization (EM) algorithm for estimating the parameter of a Markov modulated Markov process in the maximum likelihood sense is developed. This is a doubly stochastic random process with an underlying continuous-time finite-state homogeneous Markov chain. Conditioned on that chain, the observable process is a continuous-time finite-state nonhomogeneous Markov chain. The generator of the observable process at any given time is determined by the state of the underlying Markov chain at that time. The parameter of the process comprises the set of generators for the underlying and conditional Markov chains. The proposed approach generalizes an earlier approach by RydÉn for estimating the parameter of a Markov modulated Poisson process.