基于ATM的网络互连方式

ＡＴＭ技术能否在数据通信网中广泛采用取决于其是否能高效地支持现有业务，其中主要为非连接业务。本文介绍了几种基于ＡＴＭ 的非连接业务支持方式和协议体系结构，对其进行了评述并对ＩＰ分组到ＡＴＭ信元的封装效率进行了分析。     

Novel positive‐working aqueous‐base developable photosensitive polyimide precursors based on diazonaphthoquinone‐capped polyamic esters

Novel positive‐working aqueous‐base developable photosensitive polyimide (PSPI) precursors based on partially diazonaphthoquinone (DNQ)‐capped polyamic esters bearing phenolic hydroxyl groups and a DNQ photosensitive compound (PIC‐3) were developed. The partially DNQ capped polyamic esters were prepared from an esterification reaction of 1,2‐naphthoquinone diazide‐5‐sulfonyl chloride with the polyamic esters. The partially DNQ capped polyamic esters decreased the dark film loss effectively in the aqueous‐base developer and were able to make thicker film resists compared to the uncapped polyamic esters. The 25 mol % DNQ‐capped BisAPAF–PMDA polyamic ester and BisAPAF–ODPA polyamic ester containing 25 wt % PIC‐3 photosensitive compound showed a sensitivity of 176 and 185 mJ/cm², and a contrast of 1.68 and 1.02, respectively, in a 3‐μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 5 μm was obtained from both PSPI precursor compositions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2293–2300, 2003     

Synthesis and characterization of a positive‐working,aqueous‐base‐developable photosensitive polyimide precursor

A positive‐working, aqueous‐base‐developable photosensitive polyimide precursor based on poly(amic ester)‐bearing phenolic hydroxyl groups and a diazonaphthoquinone photosensitive compound was developed. The poly(amic ester) was prepared from a direct polymerization of 2,2′‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and bis(n‐butyl)ester of pyromellitic acid in the presence of phenylphosphonic dichloride as an activator. Subsequently, the thermal imidization of the poly(amic ester) precursor at 300°C produced the corresponding polyimide. The inherent viscosity of the precursor polymer was 0.23 dL/g. The cyclized polyimide showed a glass‐transition temperature at 356°C and a 5% weight loss at 474°C in nitrogen. The structures of the precursor polymer and the fully cyclized polymer were characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. The photosensitive polyimide precursor containing 25 wt % diazonaphthoquinone photoactive compound showed a sensitivity of 150 mJ/cm² and a contrast of 1.65 in a 3 μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 10 μm was obtained from this composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 352–358, 2002     

铝镁防锈铝合金塑变组织显示方法研究

采用电解抛光和阳极复膜的方法显示铝镁防锈铝合金塑变前后的晶粒（界）组织，实践表明该方法简单，方便，在正交偏振光下观察，效果良好，晶粒（界）显示清晰。     

Cascade of genetic algorithm and decision tree for cancer classification on gene expression data

Abstract: Cancer classification, through gene expression data analysis, has produced remarkable results, and has indicated that gene expression assays could significantly aid in the development of efficient cancer diagnosis and classification platforms. However, cancer classification, based on DNA array data, remains a difficult problem. The main challenge is the overwhelming number of genes relative to the number of training samples, which implies that there are a large number of irrelevant genes to be dealt with. Another challenge is from the presence of noise inherent in the data set. It makes accurate classification of data more difficult when the sample size is small. We apply genetic algorithms (GAs) with an initial solution provided by t statistics, called t‐GA, for selecting a group of relevant genes from cancer microarray data. The decision‐tree‐based cancer classifier is built on the basis of these selected genes. The performance of this approach is evaluated by comparing it to other gene selection methods using publicly available gene expression data sets. Experimental results indicate that t‐GA has the best performance among the different gene selection methods. The Z‐score figure also shows that some genes are consistently preferentially chosen by t‐GA in each data set.     

Comparison of multiple linear regression and artificial neural network in developing the objective functions of the orthopaedic screws

Optimizing the orthopaedic screws can greatly improve their biomechanical performances. However, a methodical design optimization approach requires a long time to search the best design. Thus, the surrogate objective functions of the orthopaedic screws should be accurately developed. To our knowledge, there is no study to evaluate the strengths and limitations of the surrogate methods in developing the objective functions of the orthopaedic screws. Three-dimensional finite element models for both the tibial locking screws and the spinal pedicle screws were constructed and analyzed. Then, the learning data were prepared according to the arrangement of the Taguchi orthogonal array, and the verification data were selected with use of a randomized selection. Finally, the surrogate objective functions were developed by using either the multiple linear regression or the artificial neural network. The applicability and accuracy of those surrogate methods were evaluated and discussed. The multiple linear regression method could successfully construct the objective function of the tibial locking screws, but it failed to develop the objective function of the spinal pedicle screws. The artificial neural network method showed a greater capacity of prediction in developing the objective functions for the tibial locking screws and the spinal pedicle screws than the multiple linear regression method. The artificial neural network method may be a useful option for developing the objective functions of the orthopaedic screws with a greater structural complexity. The surrogate objective functions of the orthopaedic screws could effectively decrease the time and effort required for the design optimization process.     

基于稳定固溶体团簇模型的无扩散阻挡Cu合金薄膜的成分设计

随着超大规模集成电路的发展,器件特征尺寸不断缩小,必然会出现Cu互连扩散阻挡层厚度无法进一步减小等瓶颈问题。因此,开发新型无扩散阻挡层Cu合金薄膜(Cu种籽层)势在必行。该新型互连结构在长时间的中高温(400~500℃)后续工艺实施过程中,需同时具备高的稳定性(不发生互扩散反应)和低的电阻率。基于此,首先综述了目前无扩散阻挡层结构的研究现状及问题,然后对基于稳定固溶体团簇模型设计制备的无扩散阻挡Cu-Ni-M薄膜的研究工作进行了梳理,通过多系列薄膜微观结构、电阻率及稳定性的对比,深入探讨了第三组元M的选择原则及其对薄膜热稳定性的影响。为进一步验证稳定固溶体团簇模型的有效性,对第二组元的变化进行了相关讨论。结果证实,选取原子半径略大于Cu、难扩散且难溶的元素作为第三组元M,薄膜表现出良好的扩散阻挡能力;当M/Ni=1/12,即合金元素完全以团簇形式固溶于Cu基体时,薄膜综合性能达到最优,能够满足微电子行业的要求。所有研究表明,稳定固溶体团簇模型在无扩散阻挡层Cu合金薄膜的成分设计方面十分有效,该模型也有望在耐高温Cu合金及抗辐照材料成分设计方面推广使用。     

Thermal decomposition of fluoropolymers and firing characteristics of priming compositions with fluoropolymers

Many pyrotechnics contain binders, such as nitrocellulose, Viton, and other plastics and elastomers. Most pyrotechnics are prepared by the dispersion of fuel/oxidizer ingredients in a liquid solution, which are then mixed well to form pyrotechnics. The thermal decomposition behavior of a binder is very important to pyrotechnics in a polymer. In this work, the thermal decomposition behaviors of three fluoropolymers have been investigated with differential thermal analysis/thermogravimetry and differential scanning calorimetry. The parameters concerning decomposition have been evaluated with a nonisothermal technique, and a suitable binder is suggested for the Zr/KClO₄ priming mixture. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2054–2059, 2005     

Characterization of sputtered Ta-C-N film in the Cu/barrier/Si contact system

Characterization of sputtered tantalum carbon nitride (Ta-C-N) film in Cu/barrier/Si system was reported for the first time. With a 50∶50 wt.% TaC target and an optimum N₂/Ar flow rate (in sccm) ratio of 2/24, a 600 Å-thick sputtered Ta-C-N layer was shown metallurgically stable up to 650°C annealing for 30 min, which is about 100°C higher as compared to the case without nitrogen doping. Cu diffusion through the local defects or grain boundaries of the Ta-C-N barrier layer into Si substrate is the dominant factor responsible for the failure of the Ta-C-N barrier layer after high temperature annealing.     

Electrical characteristics of nMOSFETs fabricated on hybrid orientation substrate with amorphization/templated recrystallization method

The use of hybrid orientation technology (HOT) with direct silicon bond (DSB) wafers consisting of a (1 1 0) crystal orientation layer bonded to a bulk (1 0 0) handle wafer provides promising opportunities for easier migration of bulk CMOS designs to higher performance materials. However, the material quality of nMOSFETs regions, which has been undergone amorphization/templated recrystallization (ATR) process for transforming the Si surface into (1 0 0) orientation, is still a concern because the ATR-induced defects (i.e., dislocation loops or threads) at the recrystallization layer, could degrade gate oxide integrity. In this paper, we report an investigation of charge pumping and low-frequency (1/f) noise in HOT nMOSFETs. Devices with the increased anneal time brought out a significant reduction in the charge pumping current and 1/f noise, which indicates ATR-induced defects were suppressed and consequently the “low-trap-density” of the Si/SiO₂ interface. Finally, for the first time, the behavior of 1/f noise for HOT nMOSFETs was investigated, and could be described by a unified model, i.e. a combination of carrier-number fluctuations and mobility fluctuations.