亚微米级SiO_2微球对抗撞击材料剪切增稠液的影响

采用改进的溶胶-凝胶法制备出平均粒径为150,180,200和250 nm的SiO2微球,反应温度为20~50℃,正硅酸乙酯浓度为0.2~0.3 mol/L,反应后添加0.02%~0.04%(体积分数)的硅烷偶联剂KH-570,再通过球磨将亚微米级SiO2均匀分散到PEG(聚乙二醇)中,获得相应的抗撞击体系。利用TEM、XRD、Physica MCR301型流变仪分别对不同粒径的SiO2微球的粒度分布、结构以及流变性能进行测试,结果表明,粒径为200 nm的SiO2微球制备的抗撞击体系粒度分布均匀,为非晶结构,并且表现出很好的剪切增稠现象。     

Modeling of SiO2 CVD from TEOS/ozone in a separate-gas-injection reactor

A mathematical model has been developed to study the chemical vapor deposition of SiO₂ from TEOS and ozone in a cold-wall separate-gas-injection reactor related to the commercial Watkins-Johnson 7000. The model employs the kinetic scheme proposed previously by Kim and Gill. Control-volume-based finite difference methods are used to solve for the two-dimensional fluid velocity, temperature, and concentration distributions. The model successfully describes experimental data of film thickness profiles available. We systematically investigate the dependence of deposition rate on operating conditions including O₃/TEOS ratio, reactant flow rate, and injector-wafer spacing. The predicted results indicate that a high TEOS flow rate and an O₃/TEOS ratio of around 30 are preferable for obtaining high deposition rates and good film quality.     

The integration of alternative contact cleaning techniques for future DRAM technology nodes

Conventional DRAM contact to Si cleaning methods are using wet HF-based chemistry to remove the native SiO₂ from the contact bottom and reduce the contact resistance [M.R. Baklanov, et al., J. Electrochem. Soc. 145 (9) (1998) 3240-3246]. With further scaling of the contact dimensions the distance between the contacts to the bitline (CB) and the adjacent gate conductors (GC) is decreasing. This is leading to increased parasitic capacitance between the CB and the GC and increased total bitline capacitance. The high bitline capacitance results in large signal delays, poor transfer ratio and thus bad signal margin and worse retention. In addition it is a general limitation for the number of cells attached to this bitline. For future DRAMs the need for small chip size is driving the reduction of the bitline capacitance and keeping the distance between the CB and the GC becomes a critical challenge. Typically, the material separating the CB from the GC is LPCVD TEOS. Furthermore, the selectivity of the wet HF-based chemistry of the as-deposited LPCVD TEOS to thermal SiO₂ is in the order of 3:1. This is resulting in high removal amount of LPCVD TEOS for a given removal of native SiO₂.     

Scratch resistance and adherence of novel organic-inorganic hybrid coatings on metallic and non-metallic substrates

Organic-inorganic hybrid coating material with a very high level of inorganic loading was prepared by a sol-gel process in which the initial hydrolysis and condensation steps of the inorganic precursors are separated. The coating solution was deposited onto various metallic and non-metallic substrates by a simple flow coating method. The coatings were then cured using UV radiation. The adherence of this coating material was assessed by scratch testing and indentation testing, together with electron microscope observations of the coating-substrate interfaces. The coating was shown to adhere well to aluminium, nickel and glass substrates and to adhere particularly well to polyterephthlate, polycarbonate and polymethyl methacrylate substrates. By comparison, the quality of the adherence of the coating on brass and stainless steel substrates was less good.     

VLSI中CVD二氧化硅膜的淀积

介绍了大规模集成电路中两种ＣＶＤ二氧化硅膜的淀积，并对这两种二氧化硅膜的淀积方式及其性能进行了比较。指出ＴＥＯＳ淀积方式，是今后集成电路中ＳｉＯ２淀积的主流工艺。     

Structural characterization of sol-gel composites using TEOS/MEMO as precursors

An organic/inorganic hybrid SiO₂-matrix composite was prepared through sol-gel process using TEOS and MEMO as precursors. The structures and thermal stability of the composites were investigated by various complementary techniques. The results indicate that both TEOS and MEMO hydrolyze and polymerize in sols to gelatinize and form silica-matrix materials after being baked at 60 °C. Increase of the MEMO concentration in the sols results in reduction of low-molecular compounds (such as H₂O, CH₃OH, etc.) incorporated in baked gels, thus significantly decreasing the thermal weight-loss at temperature lower that 400 °C. On the other hand, the organic functional groups bonded with -Si-O in MEMO polymerize and gelatinize to change the atomic structures and chemical states of Si in the composites. The sol-gel composites induced by TEOS/MEMO gelatinization process become pure silica after thermal treatment over 500 °C, due to decomposition and evaporation of the incorporated organic groups. It is interesting to note that from the sol containing TEOS and MEMO precursors, hydrolyzed product from MEMO precursor preferably dip-deposits compared with that from TEOS. The detailed structure analysis and mechanisms of thermal stability are analyzed in the paper.     

单体流量对大气压等离子体枪沉积二氧化硅薄膜的影响

大气压非平衡等离子体枪是近年来发展的一种新型的薄膜沉积方法,由于其相较于传统的气相镀膜方法,具有常压、低温、沉积速率快、设备简单等优点,一直以来受到了人们的广泛关注。利用这种类型沉积设备,以四乙氧基硅烷(TEOS)为先驱体,研究常压下沉积的二氧化硅薄膜的性质和规律。实验中,以氮气和少量氧气组成的混合气体作为等离子体的发生气体,以氮气作为单体的载气,并调节载气流量在60~160mL/min之间。通过光学椭偏仪、红外光谱(FT-IR)、扫描电镜(SEM)对所沉积的薄膜进行表征。结果表明,在硅衬底表面沉积的薄膜为包含OH基团的二氧化硅薄膜,且在薄膜的表面嵌有球状颗粒。随着TEOS流量的增加,薄膜中OH基团含量、表面颗粒含量和尺寸都显著增长。分析认为,TEOS流量增加引起的薄膜组分和表面形貌的变化,是由沉积速率变大引起的。     

酵母细胞壁介导的SiO2纳米结构材料的合成

根据无机盐可以在生物细胞膜上沉积形成纳米结构材料的现象和生物矿化理论,在人工培养条件下,成功地以低等真核生物细胞-酵母菌为模板,以TEOS(正硅酸乙酯)作为硅源矿化合成了一种壳鞘状的S iO2纳米结构材料,厚度达150nm左右,并采用TEM、SEM、EDX、TGA等手段对实验结果进行了表征,获得的实验数据为利用生物细胞模板合成介观尺寸有序S iO2纳米材料的提供了技术基础。     

溶胶凝胶法制备多孔SiO_2薄膜的新方法

以氨水、醋酸为催化剂,用正硅酸已酯(TEOS)为Si源,甘油作为防裂剂,聚乙烯醇(PVA1750)作为致缓剂和发泡荆,制作多孔SiO2薄膜.碱催化使得硅.羟基化合物的溶解度增大,并抑制了Si02的聚合,弱酸的二步催化使硅-羟基化合物聚合成10～100 nm的胶粒.丙三醇和TEOS水解的中间体Si(OC2H5)4-x(OH)x硅羟基形成氢键,抑制了硅-羟基化合物的聚沉,PVA的存在减缓了溶胶的聚合,在快速退火炉热处理时产生多孔结构.多孔SiO2的厚度在3μm内可调.     

正硅酸乙酯溶胶-凝胶制备壳聚糖-SiO2杂化材料

用共混法和原位杂化法分别合成了壳聚糖-SiO2杂化材料,研究了投料比对壳聚糖-SiO2杂化材料的结构以及耐水性、力学性能、Cu2+吸附性的影响.结果表明:与纯壳聚糖相比,共混法和原位杂化法合成的杂化膜材料的吸水倍率最高时分别比纯壳聚糖提高了108.3%和11.1%;共混法合成的杂化膜材料拉伸断裂强度随mTEOS/m壳聚糖的增加先增大后减小,而原位杂化法的则是随mTEOS/m壳聚糖的增加一直增大,分别比纯壳聚糖膜提高了19.9%和20.3%.同时,随着mTEOS/m壳聚糖的增大,两种方法制备的杂化材料的断裂伸长率均下降;而随着mTEOS/m壳聚糖值的增大,共混法合成的杂化膜对Cu2+的吸附能力则是先增强后逐渐降低,而原位杂化法的则一直降低.TGA分析表明:SiO2的引入并未改变壳聚糖的降解机理.SEM分析表明:复合材料是以纳米尺度的SiO2增强的杂化膜材料.