高介电HfOxNy薄膜的微结构及界面特性的研究

本文采用射频反应磁控溅射氧化铪钯的方法,在硅衬底成功制备了高介电HfOxNy薄膜.利用XRD研究了氮的参入对薄膜微结构的影响,结果表明,氮的参入可以提高薄膜的晶化温度;傅立叶红外吸收光谱研究表明高温退火导致了HfOxNy薄膜与Si之间界面层的生长,并且随着退火温度的升高,界面层逐步增厚.     

氧气对磁控溅射HfO2薄膜电学性能的影响

采用射频磁控溅射法在无氧和有氧气氛下制备了HfO2薄膜.通过X射线衍射(XRD)、X射线光电子能谱(XPS)、高分辨透射电子显微镜(HRTEM)、傅立叶变换红外光谱(FTIR)、椭圆偏振光谱(SE)以及电容-电压(C-V)测试对薄膜的结构、成分、HfO2/Si界面和HfO2栅介质MOS结构的电学性能等进行了分析表证.结果表明,溅射过程中通入氧气后,薄膜出现了较明显的结晶化;薄膜的氧化程度得到提高,成分更接近理想化学计量比HfO2.在HfO2/Si界面处存在的SiO2界面层,有氧条件下界面层的厚度增大.氧气的通入改善了HfO2栅介质MOS结构的电学性能.     

高介电HfO_xN_y薄膜的制备及其光学性能研究

采用直流反应磁控溅射方法,在硅衬底制备了高介电HfOxNy薄膜。用椭偏仪研究了后期退火处理对薄膜光学性质的影响,结果表明,薄膜的折射率随退火温度的升高而增加,这主要是由于高温退火导致薄膜内部缺陷减少,使得薄膜松散的内部结构变得更加致密;薄膜的消光系数随退火温度的升高而降低,这是由于因为退火后薄膜内的缺陷减少。光学禁带宽度随退火温度的升高而增加,这是由于退火过程中薄膜中N含量的减少而导致。     

基于金属浮栅层有机薄膜非易失性存储器的制备与表征

以聚甲基丙烯酸甲酯(PMMA)为栅介质,以并五苯为有机薄膜制备了有机薄膜非易失性存储器,研究基于热蒸发金属金浮栅层的存储行为。在2 s脉冲的偏压下,浮栅层通过充放电过程可导致明显的阈值电压偏移。在1 V的脉冲电压下可实现电荷的写入/擦除操作,在6 V的脉冲电压下可获得30.0 V的存储窗口。实验结果表明,基于金属浮栅层并以并五苯作为有机薄膜来制备非易失性存储器具有一定的研究价值和应用前景。     

CVD反应器中成膜与成核竞争机制的实验研究

利用管式热化学气相淀积反应器,研究了化学气相淀积过程中成核与成膜的竞争机制。结果表明,增加反应器操作压力、提高反应温度和反应物浓度,有利于粒子的生成而不利于薄膜淀积。在反应器中,淀积薄膜的表面形态各不相同。     

高介电材料Y2O3 薄膜的微结构及界面特性的研究

采用射频反应磁控溅射金属钇耙的方法,在硅衬底成功制备了高介电Y2O3薄膜.并深入研究了Y2O3薄膜的微结构和Y2O3/Si 体系的界面结构在高温退火过程中的变化规律.研究结果表明:在400～500 ℃之间,Y2O3 薄膜有一个从单斜相向立方相的物相结构转变过程.在高温退火过程中,Y2O3/Si有界面层SiO2生成,并且随着退火温度增加,界面层SiO2 的厚度也在逐渐增加.     

二氧化铪（HfO2）薄膜制备的研究进展

随着集成电路的迅速发展。高K值栅介质材料将成为下一代MOS器件最具有希望的候选材料。HfO2具有宽带隙和高介电常数而备受关注。本文简述了HfO2薄膜的制备方法及研究进展。     

真空淀积法

真空淀积法是在真空中淀积金属薄膜的方法。事实上,用真空淀积方法淀积的薄膜,并不限于金属;就是金属与非金属的化合物,只要这些物质在蒸发温度时不分解,而其蒸气压也不过低的,都可以淀积而成薄膜。玻璃、塑料、陶瓷等电介质以及铁、锌等金属导体,都可以作为淀积金属的载体。     

银含量对射频磁控溅射法制备Ag-TiO_2薄膜能隙和相结构的影响

采取射频磁控溅射法在硅和石英衬底上淀积Ag-TiO_2纳米薄膜,利用X射线衍射仪和紫外可见分光计分析薄膜的相结构和光学性能,研究银含量对Ag-TiO_2薄膜相结构和能隙的影响.结果表明:银含量影响Ag-TiO_2薄膜的相结构,薄膜中的银为金属Ag(Ag~0),随着银含量(0~40%,体积分数)的增加,薄膜的能隙先减后增,但是仍然小于纯TiO_2薄膜的能隙,银的添加明显地改善了TiO_2薄膜对可见光的吸收.     

保护膜厚度对磁光记录薄膜磁特性的影响

本文利用射频磁控溅射方法制备出AIN／TbFeCo／基片磁光薄膜，在磁光记录薄膜上覆盖一层AIN介质薄膜不仅可以防止磁光记录薄膜的氧化而且可以增强磁光克尔效应。在实验中发现AIN薄膜厚度的变化也会影响磁光记录薄膜的磁特性。当AIN厚度从0开始增加时，薄膜的矫顽力随着AIN膜厚的增加而增加，在一定AIN厚度时达到最大值。然后随着AIN膜厚的增加，矫顽力逐渐减小。垂直各向异性常数随AIN膜厚的变化有着同样的规律。研究清楚这一现象对制备实用化磁光盘有着重要的意义，应用应力机制对此现象作出了圆满的解释     

Fabrication of a new type of organic-inorganic hybrid superlattice films combined with titanium oxide and polydiacetylene

We fabricated a new organic-inorganic hybrid superlattice film using molecular layer deposition [MLD] combined with atomic layer deposition [ALD]. In the molecular layer deposition process, polydiacetylene [PDA] layers were grown by repeated sequential adsorption of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet polymerization under a substrate temperature of 100°C. Titanium oxide [TiO₂] inorganic layers were deposited at the same temperatures with alternating surface-saturating reactions of titanium tetrachloride and water. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the nanohybrid films. The transmission electron microscopy analysis of the titanium oxide cross-linked polydiacetylene [TiOPDA]-TiO₂ thin films confirmed the MLD growth rate and showed that the films are amorphous superlattices. Composition and polymerization of the films were confirmed by infrared spectroscopy. The TiOPDA-TiO₂ nanohybrid superlattice films exhibited good thermal and mechanical stabilities.     

Interplay between adhesion and interfacial properties of diamond films deposited on WC-10%Co substrates using a CrN interlayer

In this study, the effect of deposition temperature on the adhesion of diamond films deposited on WC-10%Co substrates with a Cr-N interlayer is investigated. Diamond films were deposited at different temperatures (550, 650 and 750 °C), using a hot filament chemical vapor deposition reactor. It was found that the optimal adhesion is obtained for the film deposited at 650 °C. The interplay between carbon interfacial diffusion and the adhesion of diamond films deposited at different deposition temperatures were investigated. The combined use of different characterization techniques (Indentation tests, SIMS, XPS, XRD and SEM) shows that the adhesion strength depends on the thickness of Cr-C layer formed at the interface during diamond deposition, which is strongly influenced by the deposition temperature. It is suggested that at the optimum deposition temperature, thickness of the Cr-C layer is too low to introduce a large thermal stress at the interface and sufficiently thick enough to withstand the propagation of indentation induced cracks.     

Interfacial polymerization of polyaniline and its layer‐by‐layer assembly into polyelectrolytes multilayer thin‐films

The layer‐by‐layer (LbL) self assembly deposition technique was used to prepare multilayer thin films of anionic polyaniline‐blend‐poly(sodium 4‐styrenesulfonate) (PANI‐PSS) and cationic poly(diallydimethylammonium chloride) (PDADMAC). Anionic polyaniline was prepared by the interfacial polymerization of aniline monomer in the presence of PSS which acted as template to provide water solubility. The PSS to PANI concentration ratios used in the synthesis step was found to have a major effect on the final PANI‐PSS synthesis, its self assembly and the electrical properties of the prepared films. The optical and electrical properties of the films were measured by ultraviolet‐visible spectroscopy (UV‐Vis) and a 4‐point probe setup, respectively while the thickness of the films was measured by atomic force microscopy (AFM). Results showed that the optimum condition for the film growth and optimal conductivity were obtained with different synthesis conditions. These results suggest that the PSS concentration used for interfacial synthesis of PANI must be finely tuned depending on the type of application aimed by the user. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Low-temperature deposition of optically transparent diamond using a low-pressure flat flame

The radial uniformity and scaleable nature of flat flames make them an attractive technique for diamond deposition. Due to the high temperatures involved in combustion synthesis, typically molybdenum and silicon have been used as substrates. Here we report low-temperature diamond deposition on glass substrates. Diamond deposition was achieved on ordinary sodium silicate glass at substrate temperatures of 500°C; however, film delamination occurred during cooling after deposition. Vycor™ and Pyrex™ are two glasses that have thermal expansion coefficients that are similar to diamond. Continuous, optically transparent films were successfully deposited on both glasses. The diamond films have been characterized by scanning electron microscopy, Raman spectroscopy and secondary ion mass spectroscopy (SIMS). The dependence of hydrogen and sp²-bonded carbon incorporation in the films on reactant composition was quantified. These films were optically transparent and showed good adhesion as measured by a simple tape test.     

A study on the conduction path in undoped polycrystalline diamond films

The conduction path in as-grown undoped diamond films deposited by chemical vapor deposition has been investigated by employing impedance spectroscopy, electroplating and electroetching. The thickness- and direction-dependencies of electrical resistivity did not agree with the previously known surface conduction model. The Cu electroplating and Ag electroetching results showed that the current path followed the grain boundaries within the diamond films. The Cu electroplating of diamond film with an insulating surface layer also showed that the grain boundaries within the films were the main conduction path in undoped polycrystalline films.     

Multilayered graphene films prepared at moderate temperatures using energetic physical vapour deposition

Carbon films were energetically deposited onto copper and nickel foil using a filtered cathodic vacuum arc deposition system. Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–visible spectroscopy showed that graphene films of uniform thickness with up to 10 layers can be deposited onto copper foil at moderate temperatures of 750 °C. The resulting films, which can be prepared at high deposition rates, were comparable to graphene films grown at 1050 °C using chemical vapour deposition (CVD). This difference in growth temperature is attributed to dynamic annealing which occurs as the film grows from the energetic carbon flux. In the case of nickel substrates, it was found that graphene films can also be prepared at moderate substrate temperatures. However much higher carbon doses were required, indicating that the growth mode differs between substrates as observed in CVD grown graphene. The films deposited onto nickel were also highly non uniform in thickness, indicating that the grain structure of the nickel substrate influenced the growth of graphene layers.     

Removal of sp2-boron nitride transition layer in the growth of cubic boron nitride films

Practical application of cubic boron nitride (cBN) films is known to be hindered by its bad adhesion to substrates. One reason is that an sp²-bonded boron nitride (sp²-BN) transition layer is formed on the substrate surface at the early stage of deposition prior to the nucleation of cBN, which weakens the link between the cBN-rich layer and the substrate. In this study, we demonstrated the feasibility of removing this sp²-BN layer, by replacing it with a zirconium- (Zr-) rich composite layer. The method is to deposit a multilayer of Zr layer/sp²-BN layer/cBN-rich layer at 680 °C on a tungsten carbide substrate, followed by annealing the structure at 850 °C for 1 h. X-ray photoelectron spectroscopy, transmission electron microscopy and electron energy loss spectroscopy analyses showed that the Zr metal layer and sp²-BN layer reacted completely, to produce a composite interfacial layer consisting of metal Zr, Zr nitride, boride and oxide. The depth profiles of the elemental distributions and chemical states were investigated and discussed to reveal the diffusion of the elements associated with this deposition process.     

The role of ion-induced substrate damage in thin film adhesion strength

Variable-energy positrons are combined with Auger electron spectroscopy, scanning electron microscopy, and scratch test critical load measurements to study interfacial properties in thin film adhesion. This work complements an earlier investigation of the adhesion strength enhancement produced by ion bombardment of the substrate surface before deposition. In this study, we have investigated SiO₂ films deposited by radio-frequency (RF) sputtering onto stainless steel substrates. Extended ion bombardment etching leads to three related effects: the scratch test critical load is increased significantly, Auger electron spectroscopy shows a greater penetration of the film material into the substrate; and the interfacial positron annihilation signal is dominated by large, open-volume defects. These results are interpreted as confirmation that ion bombardment leads to the formation of microvoids in the interface layer and, consequently, to an increased adhesion strength by allowing mechanical interlocking between the coating and the substrate.     

Two-step growth of ZnO films on silicon by atomic layer deposition

Two-step growth of ZnO by atomic layer deposition at low temperatures was performed to grow quality ZnO films on silicon substrates: first, the growth of a buffer layer at 130 ?C and second, the growth of the main layer at 210 ?C. Structural and optical properties of the ZnO films deposited on ZnO-buffer/Si(111) were investigated as a function of buffer layer thickness. The films showed a strong UV emission at 380 nm and a weak green emission at 520–570 nm. The ZnO films deposited on a 327 å buffer layer showed overall the best surface morphology and structural and optical properties.