Optical studies of TiO2–lead phthalocyanine nanocomposite thin films prepared by electron beam evaporation

The nanocomposite thin films of titanium dioxide (TiO₂)–lead phthalocyanine (PbPc) have been prepared on glass substrates by the electron beam evaporation technique. The optical properties of TiO₂/PbPc nanocomposite thin films have been investigated using a spectrophotometric measurement of the absorbance and transmittance at normal incident of light in the wavelength region 300–800 nm. Surface morphology of thin films has been characterized using field emission scanning electron microscopy (FESEM). The UV–vis analysis has been performed to determine the type of electronic transition and the optical energy band gap. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals that the absorption mechanism is due to direct transition. Moreover, by studying the absorption coefficient spectra just below the fundamental absorption edge, the width of band tails of localized states (Urbach energy), steepness parameter and width of the defect states have been evaluated. The obtained results of this novel nanocomposite (TiO₂/PbPc) support the desirable features for the optoelectronic devices.     

The effects of titanium films on secondary electron emission phenomena in resonant cavities and at dielectric surfaces

The phenomenon of electron bombardment heating of insulators in vacuum under the influence of RF fields by several types of multipactor processes is reviewed. Evidence is given to show that a practical way of limiting the electron bombardment of insulators is to provide surfaces which have a maximum secondary electron emission yield of less than one on both the insulator and on the related metal surfaces. Thin films of titanium metal are shown to have a very good effect on suppressing the secondary electron multiplication processes at both the metal and dielectric. The discontinuous nature of very thin metal films makes it possible to coat dielectrics with titanium with thicknesses sufficient to reduce the secondary emission yield without adding significantly to the loss factor or to the dc conductivity.     

PECVD法制备硅化钛膜的工艺研究

硅化钛薄膜由于电阻率低和其它一些良好特性,在VLSI的栅电极和互连线中显示出它潜在的优势。本文研究了用PECVD法制备硅化钛膜的卫艺。结果表明:所形成硅化钛膜的性质强烈地依赖于淀积工艺条件。还确定了典型工艺条件,并用俄歇电子能谱分析了硅化钛膜的组分。     

PET复合衬底上梯度介质薄膜厚度的椭偏表征

为了监控3维玻璃上聚对苯二甲酸乙二醇酯(PET)复合衬底介质膜膜厚, 采用将PET复合衬底等效为单层基底材料的建模分析方法, 通过椭偏测量技术实现了复杂衬底上TiO₂梯度折射率材料薄膜厚度的检测。结果表明, 采用该方法测量的PET复合衬底上TiO₂梯度折射率薄膜厚度为212.48nm, 扫描电子显微镜的测量结果为211nm, 结果非常准确。以TiO₂为例验证了等效衬底方法, 该方法也同样适用于其它介质膜。等效衬底法可实现PET复合衬底上的TiO₂薄膜厚度的高精度测量表征, 对镀膜工艺过程监控具有重要意义。     

Effect of rapid thermally nitrided titanium films contacting silicided and nonsilicided junctions

The effect of rapid thermally nitrided titanium films contacting silicided (titanium disilicided) and nonsilicided junctions has been studied in the temperature range of 800 to 900°C. The rapid thermal nitridation of titanium films used as diffusion barriers between aluminum and silicon, has a major impact on shallow junction complementary metal oxide semiconductor technologies. During the process of rapid thermal nitridation, the dopants in the junctions undergo a redistribution and affect the electrical properties of shallow junction structures. This work focuses on using novel contact resistance structures to measure the variation in electrical parameters for rapid thermally nitrided titanium films annealed at different temperatures. The self-aligned silicide (salicide) junctions in this study were formed using rapid thermally annealed titanium films. Electrical contact resistance testers were used to measure the interface contact resistance between the salicide and silicon, as well as between the metal and the salicide. The results show that the interface contact resistance to the p⁻ diffused salicided junctions increases with rapid thermal nitridation of the additional titanium film, whereas the interface contact resistance to the n⁻ diffused salicided junction shows a decrease. Further, as a function of the rapid thermal annealing temperature (for fixed titanium thickness), the nonsalicided diffusions show an increase in the interface contact resistance. The boron profiles at the TiSi₂/Si interface obtained using secondary ion mass spectroscopy show an excellent qualitative agreement with the electrical results for each of the conditions discussed. The films were also characterized using Rutherford back-scattering spectrometry and transmission electron microscopy and the results show good agreement with the measured variation in electrical parameters. These results also show that as the anneal temperature is increased, the TiN thickness increases, further the change in the silicide/silicon interface position with the nitridation of the additional titanium layer was verified. This work was carried out when the author was working at AT&T Bell Labs     

Nanoscale structural characteristics and electron field emission properties of transition metal–fullerene compound TiC60 films

Transition-metal compound TiC₆₀ thin films were grown by co-deposition from two separated sources of fullerene C₆₀ powder and titanium. Study of structural properties of the films, by Raman spectroscopy, atomic force microscopy, and scanning tunneling spectroscopy reveals that the films have a deformed C₆₀ structure with certain amount of sp³ bonds and a rough surface with a large number of nanoclusters. z–V tunnelling spectroscopic measurements suggest that several charge transport mechanisms are involved in as the tip penetrates into the thin film. Conventional field electron emission (FEE) measurements show a high emission current density of 10 mA/cm² and a low turn-on field less than 8 V/μm, with the field enhancement factors being 659 and 1947 for low-field region and high-field region, respectively. By exploiting STM tunneling spectroscopy, local FEE on nanometer scale has also been characterized in comparison with the conventional FEE. The respective field enhancement factors are estimated to be 99–355 for a gap varying from 36 to 6 nm. The enhanced FEE of TiC₆₀ thin films can be ascribed to structural variation of C₆₀ in the films and the electrical conducting paths formed by titanium nanocrystallites embedded in C₆₀ matrix.     

Pulsed laser deposition of titanium nitride and diamond-like carbon films on polymers

We have investigated the deposition of titanium nitride (TiN) and diamond-like carbon (DLC ) films on polymethylmethacrylate (PMMA) substrates using pulsed laser deposition (PLD) technique. The TiN and diamond-like films were deposited by laser ablation (KrF excimer laser λ = 248 nm, pulse duration τ～25 × 10^?9 s, energy density ～2?15J/cm²) of TiN and graphite targets, respectively, at room temperature. These films were characterized by transmission electron microscopy, scanning electron microscopy, x-ray diffraction, Auger electron spectroscopy, UV-visible absorption spectroscopy, and Raman spectroscopy. The TiN films were smooth and found to be polycrystalline with average grain size of 120Å. The diamond-like carbon films were amorphous with a characteristic Raman peak at 1550 cm^?1. The TiN films are highly adherent to the polymer substrates as compare to DLC films. The adhesion strength of DLC films on polymers was increased by interposing thin TiN layer (200Å) on polymers byin-situ pulsed laser deposition. The DLC films were found to be amorphous with good adhesion to TiN/PMMA substrates.     

气体流量比对PECVD硅化钛薄膜性质的影响

本文报道了以四氯化钛(TiCl_4)和硅烷(SiH_4)为源物质,采用等离子增强化学气相淀积工艺(PECVD)制备硅化钛薄膜的方法;着重研究了气体流量比变化对薄膜电阻率、淀积速率以及化学组成的影响,通过实验获得了制备优良硅化钛薄膜的最佳气流比条件。     

聚甲基丙烯酸甲酯LB膜用作高分辨率电子束抗蚀层的研究

应用LB技术制备了厚度为20100nm的聚甲基丙烯酸甲酯(PMMA)超薄高分辨率电子束抗蚀层。应用改装的日立S-450扫描电子显微镜(SEM),研究了PMMALB膜的曝光特性和刻蚀条件。结果得到线宽0.15m的铝掩模光栅图形,表明此种超薄膜具有良好的分辨率和足够的抗蚀性。     

沉积温度对电子束蒸发沉积ZrO2薄膜性质的影响

摘要ZrO2薄膜样品在不同的沉积温度下用电子束蒸发的方法沉积而成。利用X射线衍射(XRD)仪和原子力显微镜(AFM)检测了ZrO2薄膜的晶体结构和表面形貌，发现室温下沉积ZrO2薄膜样品为非晶结构，随着沉积温度升高．ZrO2薄膜出现明显的结晶现象，在薄膜中同时存在四方相及单斜相。薄膜表现为自由取向生长，晶粒尺寸随沉积温度升高而增大。同时发现薄膜中的残余应力随沉积温度的升高，由张应力状态变为压应力状态，这一变化主要是薄膜结构变化引起的内应力的作用结果。同时讨论了不同沉积温度对ZrO2薄膜光学性质的影响。     

Photovoltaic properties of interfaces of organic films of substituted perylene with TiO<Subscript>2</Subscript> and SnO<Subscript>2</Subscript> surfaces

The photovoltaic effect has been detected and studied in structures based on ultrathin vacuum-deposited organic films of perylene-3,4,9,10-tetracarboxylic acid dianhydride on the titanium and tin dioxide surfaces. The interfacial potential barrier shape in these structures is studied by low-energy electron total current spectroscopy. Changes in the surface potential upon exposure to visible light are recorded in situ using an electron-beam probe with energies from 0 to 25 eV. The photovoltage is detected at incident photon energies of 1.5–2.5 eV, which corresponds to the organic film absorption range and simultaneously to the transmission band of titanium and tin dioxides. An analysis of the spectral distributions and transient responses shows that two components of the observed photovoltage can be distinguished. The relation of one of the components to the excitation of interband transitions in the organic film and another component to electronic transitions involving interfacial energy states are discussed.     

Specific features of the morphology of titanium oxide films prepared by pulling silicon substrates from a solution

The formation of thin titanium oxide films by pulling substrates from an alcohol solution of titanium tetraisopropoxide has been investigated. It is shown that the deposited titanium oxide layer consists of a continuous film and titanium oxide globules on its surface. It is found that the density and height of the globules depend on the pulling rate from the solution and the relative humidity in the working chamber, while the thickness of the continuous titanium oxide film is relatively constant.     

Layered and Homogeneous Films of Aluminum and Aluminum/Silicon with Titanium and Tungsten for Multilevel Interconnects

Layered structures and homogeneous alloy films synthesized by sputter deposition were investigated for use in a VLSI multilevel interconnect technology. Major areas studied include hillock formation, resistivity before and after annealing, film composition and structure, reproducibility, interlevel shorts, and dry etching. It has been demonstrated in this work that aluminum alloyed with silicon and titanium and layered with titanium offers advantages over current technological materials for interconnections in integrated circuits. Measurements of surface roughness and electrical shorts between two levels of metal showed that the hillock densities in the films are significantly reduced when small amounts (one to three atomic percent) of titanium and silicon are present. The resistivity of such homogeneous films, however, is 4.5 to 5.5 /spl mu//spl Omega//spl dot/cm, which is higher than standard metallization alloys. When Al/Si was layered with Ti, no hillocks were observed and the resistivity of the composite films was comparable to standard metallization alloys.     

Layered and homogeneous films of aluminum and aluminum/silicon with titanium and tungsten for multilevel interconnects

Layered structures and homogeneous alloy films synthesized by sputter deposition were investigated for use in a VLSI multilevel interconnect technology. Major areas studied include hillock formation, resistivity before and after annealing, film composition and structure, reproducibility, interlevel shorts, and dry etching. It has been demonstrated in this work that aluminum alloyed with silicon and titanium and layered with titanium offers advantages over current technological materials for interconnections in integrated circuits. Measurements of surface roughness and electrical shorts between two levels of metal showed that the hillock densities in the films are significantly reduced when small amounts (one to three atomic percent) of titanium and silicon are present. The resistivity of such homogeneous films, however, is 4.5 to 5.5 µΩ.cm, which is higher than standard metallization alloys. When Al/Si was layered with Ti, no hillocks were observed and the resistivity of the composite films was comparable to standard metallization alloys.     

钛酸钡膜的制备、结构及结合强度

采用微弧氧化在钛合金表面制备BaTiO3膜。讨论电解液组分、反应时间及电压对BaTiO3膜形态和相组成的影响,并评价BaTiO3膜的结合强度。结果表明,BaTiO3的生成量随电解液浓度和氧化时间的增大而增加;其表面形貌也受电解液浓度、电压和氧化时间的影响;电压降低,膜层的结合强度有增大的趋势。电压为80 V时,结合强度可达36.4 MPa,优于一般等离子喷涂技术获得的膜层结合强度。     

Reduced oxide charge trapping and improved hot-electron reliabilityin submicrometer MOS devices fabricated by titanium salicideprocess

The effects of the titanium salicide (self-aligned silicide) process on the reliability of very-thin-gate-oxide MOSFETs have been studied. It is shown that the titanium salicide process, as compared to the conventional poly-Si gate process, has reduced electron and hole trapping in the oxide and improved hot-electron reliability. It is shown that these phenomena are related to the reduced hydrogen content in the oxide as revealed by a secondary ion mass spectrometry (SIMS) analysis     

用于动态红外景物模拟器的超薄氮化钛薄膜

针对动态红外景物模拟器的应用要求,用磁过滤电弧离子镀方法制备了超薄氮化钛薄膜。制备的薄膜厚度介于7. 5nm 至75nm。重点研究了薄膜的微观结构、电阻温度系数、电阻温度稳定性、薄膜的微加工等性质。实验结果表明,氮化钛薄膜是一种良好的辐射电阻材料。     

Praseodymium based high-k dielectrics grown on Si and SiC substrates

High-k polycrystalline Pr₂O₃ thin films have been deposited by metal organic chemical vapor deposition (MOCVD) technique on Si(0 0 1) and 4H–SiC(0 0 0 1) substrates. MOCVD processes have been carried out from the Pr(tmhd)₃ (H-tmhd= 2,2,6,6-tetramethyl-3,5-heptandione) precursor. Complete structural and morphological characterization of films has been carried out using several techniques (X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM)). Polycrystalline Pr₂O₃ films have been obtained and at the interface a praseodymium silicate amorphous layer has been observed on both substrates. The electrical properties of the dielectric praseodymium films have been evaluated.     

POLYMETHYLMETHACRYLATE LANGMUIR-BLODGETT FILMS FOR HIGH RESOLUTION ELECTRON BEAM RESIST

Ultra-thin (20-100nm) polymethylmethacrylate(PMMA) films prepared by Langmuir-Blodgett techniques have been explored as high resolution electron beam resists. A Hitachi S-450 Scanning Electron Microscope (SEM) has been refitted for a high resolution electron beam exposure system. The lithographic properties and exposure conditions of LB PMMA films were investigated. 0.15μm lines-and-spaces patterns were achieved by using the SEM as the exposure tool. The results demonstrate that the etch resistance of such films is sufficiently good to allow patterning of a 20 nm aluminum film suitable for mask fabrication.     

热丝化学气相沉积法低温制备纳米晶态碳化硅薄膜

采用热丝化学气相沉积(HFCVD)技术以甲烷(CH4)和硅烷(SiH4)作为源反应气体在Si(111)衬底上合成了纳米晶态SiC薄膜。通过X射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)以及光致发光(PL)检测技术对薄膜的晶体结构、表面形貌和PL特性进行了分析和表征。结果表明，在较低的衬底温度下所沉积的薄膜是由镶嵌于非晶SiC网络中的晶态纳米SiC构成。纳米晶粒平均尺寸约为6nm。室温下用HeCr激光激发样品，观到薄膜发出波长位于400～550nm范围内可见光辐射。