Laser-induced site-selective silver seeding on polyimide for electroless copper plating

Ag particles were generated on Ag⁺-doped polyimide film by laser direct writing, followed by selective copper deposition using the metallic silver particles as seeds. Laser irradiation caused in situ reduction and agglomeration of silver on the polyimide film. The copper lines were less uniform and compact with higher scanning velocity and the width of the deposited copper line could reach 25 μm. Equations of the relationship between scanning velocity and connectivity of the deposited copper patterns have been derived. The process was characterised by AFM, XPS, SEM, and semiconductor characterisation system.     

Properties of Cu film and Ti/Cu film on polyimide prepared by ion beam techniques

Cu film and Ti/Cu film on polyimide substrate were prepared by ion implantation and ion beam assisted deposition (IBAD) techniques. Three-dimension white-light interfering profilometer was used to measure thickness of each film. The thickness of the Cu film and Ti/Cu film ranged between 490 nm and 640 nm. The depth profile, surface morphology, roughness, adhesion, nanohardness, and modulus of the Cu and Ti/Cu films were measured by scanning Auger nanoprobe (SAN), atomic force microscopy (AFM), and nanoindenter, respectively. The polyimide substrates irradiated with argon ions were analyzed by scanning electron microscopy (SEM) and AFM. The results suggested that both the Cu film and Ti/Cu film were of good adhesion with polyimide substrate, and ion beam techniques were suitable to prepare thin metal film on polyimide.     

Effect of temperature on pulsed laser deposition of ZnO films

ZnO thin films have been deposited on Si(1 1 1) substrates at different substrate temperature by pulsed laser deposition (PLD) of ZnO target in oxygen atmosphere. An Nd:YAG pulsed laser with a wavelength of 1064 nm was used as laser source. The influences of the deposition temperature on the thickness, crystallinity, surface morphology and optical properties of ZnO films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), photoluminescence (PL) spectrum and infrared spectrum. The results show that in our experimental conditions, the ZnO thin films deposited at 400 °C have the best surface morphology and crystalline quality. And the PL spectrum with the strongest ultraviolet (UV) peak and blue peak is observed in this condition.     

Deposition characteristics of copper particles on roughened substrates through kinetic spraying

In this paper, a systematic study of copper particle deposition behavior on polished and roughened surfaces (aluminum and copper) in kinetic spray process has been performed. The particle deformation behavior was simulated through finite element analysis (FEA) software ABAQUS explicit 6.7-2. The particle-substrate contact time, contact temperature and contact area upon impact have been estimated for smooth and three different roughened substrate cases. Copper powders were deposited on smooth and grit-blasted copper and aluminium substrates and characterized through scanning electron microscopy and Romulus bond strength analyzer. The results indicate that the deformation and the resultant bonding were higher for the roughened substrates than that of smooth. The characteristic factors for bonding are reported and discussed. Thus the substrate roughness appears to be beneficial for the initial deposition efficiency of the kinetic spray process.     

In situ functionalized self-assembled monolayer surfaces for selective chemical vapor deposition of copper

Recent studies show that the self-assembled monolayer (SAM) is well suited to control the selectivity of chemical vapor deposition (CVD). Here, we reported the selective CVD for copper on the functionalized SAM surfaces (with -SH, -SS-, and -SO₃H terminal groups). The -SS- and -SO₃H terminal group surfaces were obtained through in situ chemical transformation of -SH terminal group surface of a 3-mercaptopropyltrimethoxysilane-SAM (MPTMS-SAM). As a result, the -SS- terminal group surface reduces copper deposition and the -SO₃H terminal group surface enhances copper deposition comparing to the -SH terminal group surface. In addition, the MPTMS-SAM was irradiated by UV-light through a photo mask to prepare SH-group and OH-group regions. Then, copper films were deposited only on the SH-group region of the substrate in chemical vapor deposition. Finally, patterns of copper films were formed in the way of UV-light irradiation. These results are expected for use of selective deposition of copper metallization patterns in IC manufacturing processes.     

Pulsed laser deposition of hydroxyapatite film on laser gas nitriding NiTi substrate

A hydroxyapatite (HA) film was deposited on laser gas nitriding (LGN) NiTi alloy substrate using pulsed laser deposition technique. TiN dendrite prepared by LGN provided a higher number of nucleation sites for HA film deposition, which resulted in that a lot number of HA particles were deposited on TiN dendrites. Moreover, the rough LGN surface could make the interface adhesive strength between HA film and substrate increase as compared with that on bare NiTi substrate.     

Field emissions of graphene films deposited on different substrates by CVD system

<正>Graphene films are deposited on copper(Cu) and aluminum(Al) substrates,respectively,by using a microwave plasma chemical vapour deposition technique.Furthermore,these graphene films are characterized by a field emission type scanning electron microscope(FE-SEM),Raman spectra,and field emission(FE) I-V measurements.It is found that the surface morphologies of the films deposited on Cu and Al substrates are different:the field emission property of graphene film deposited on the Cu substrate is better than that on the Al substrate,and the lowest turn-on field of 2.4 V/μm is obtained for graphene film deposited on the Cu substrate.The macroscopic areas of the graphene samples are all above 400 mm~2.     

Solid freeform fabrication of alumina using laser-assisted ESAVD

Electrostatic spray assisted vapour deposition (ESAVD) has been used successfully to produce films and coatings. A combination of laser-assisted (LA) deposition and ESAVD has been developed for the direct fabrication of alumina ceramics. This novel laser-assisted ESAVD technique involves spraying a liquid precursor onto a substrate whilst a laser beam is simultaneously used to heat the precursor and cause the decomposition and chemical reactions of the precursor in order to produce a solid deposit. A desired three-dimensional (3-D) object can be formed through layer-by-layer deposition using a computer-controlled platform. Dense or porous alumina ceramics can be deposited on the substrate by optimizing the processing parameters. This paper reports the fabrication of alumina parts by the laser-assisted ESAVD method. The effect of processing parameters including laser scanning speed, laser beam size and laser power on the microstructure will be presented. Scanning electron microscope (SEM) and X-ray diffraction (XRD) have been used to characterise the phase and structure of the deposited alumina parts.     

Low thermal emissive surface properties of ZnO/polyimide composites prepared by pulsed laser deposition

We report the low thermal-emissive surface properties of composites of ZnO-polyimide. The composites were synthesized by depositing ZnO on polyimide surface by pulsed laser deposition technique. ZnO target was ablated at different incident energy densities and the substrate (polyimide) was held at elevated temperature. This facilitated the c-axis oriented growth of ZnO, which was inferred from the X-ray diffraction analysis. The composites consisted of multilayers having different electrical resistivities. The values of which are also estimated from Hagen-Rubens relation. The reduced infrared emissivities of the composite films, as compared to polyimide, were correlated to the increased carrier concentration and reduced surface resistivity estimated from the Hall measurements.     

Diamond coating deposition by synergy of thermal and laser methods—A problem revisited

Diamond coatings were deposited by synergy of the hot filament CVD method and the pulse TEA CO₂ laser, in spectroactive and spectroinactive diamond precursor atmospheres. Resulting diamond coatings are interpreted relying on evidence of scanning electron microscopy as well as microRaman spectroscopy. Thermal synergy component (hot filament) possesses an activating agent for diamond deposition, and contributes significantly to quality and extent of diamond deposition. Laser synergy component comprises a solid surface modification as well as the spectroactive gaseous atmosphere modification. Surface modification consists in changes of the diamond coating being deposited and, at the same time, in changes of the substrate surface structure. Laser modification of the spectroactive diamond precursor atmosphere means specific consumption of the precursor, which enables to skip the deposition on a defined substrate location. The resulting process of diamond coating elimination from certain, desired locations using the CO₂ laser might contribute to tailoring diamond coatings for particular applications. Additionally, the substrate laser modification could be optimized by choice of a proper spectroactive precursor concentration, or by a laser radiation multiple pass through an absorbing medium.     

Time-resolved dynamics analysis of nanoparticles applying dual femtosecond laser pulses

The evolution of a fs laser generated plume on copper was studied by dual laser pulses. The plume generated by the first pulse (620 nm) was excited by the second, delayed pulse (310 nm). The actual state of the plume was monitored by detecting the intensities of the emitted light and the reflected delayed pulse from the interaction range, i.e. 0–150 μm above the surface. Four peaks were observed in the 0–1400 ps time range and assigned to appearance of electrons, ions, atomic species and nanoparticles. Accordingly, the timing of the creation and ejection of these species was determined. By integrating the intensity of the nanoparticle peak, the production yield of the nanoparticles and its dependence on the ablating laser fluence was calculated. The ablation products were deposited on a Si substrate, too, and analyzed by atomic force microscopy and scanning electron microscopy. The results of the deposition and the dual-pulse experiments are in good agreement with the theory. PACS 52.38.Mf; 79.20.Ds; 61.80.Ba     

Preparation of Sn films deposited on carbon nanotubes

In this work carbon nanotubes were first grown on copper substrate by chemical vapor deposition method. The Sn deposits were then deposited on the surface of as-grown carbon nanotubes by three different methods: electroplating, electroless plating and displacing methods. The Sn deposits on CNTs surface were characterized by both scanning electron microscope and field emission scanning electron microscope. The compositions of Sn deposits were analyzed by energy dispersive X-ray spectroscope. The results showed that both electroless plating and displacing deposits can but the electroplating deposits cannot cover on the surface of CNTs. Besides C, Sn, Ni and Pd, the electroless deposits also contain element of oxygen and the displacing deposits also contain elements of copper and oxygen.     

Electrodeposition of cobalt with tunable morphology from reverse micellar solution

Electrodeposition of cobalt on a copper electrode was successfully performed from aqueous and reverse micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), using constant potential electrolysis method. The potential to be applied for electrodeposition was judged from the cyclic voltammetric behavior of cobalt(II) in aqueous and reverse micellar solutions of CTAB at different compositions. The morphology, dimension, and crystallinity of cobalt deposited onto a copper substrate were evaluated from scanning electron microscopy (SEM) images and X-ray diffraction technique. The cobalt deposited on copper from aqueous solution does not show any definite shape and size, while the deposition from reverse micellar solutions occurred with definite shapes such as star-, flower-, and nanorod-like structures depending on the composition. The slow kinetics governed by the reverse micelles associated with the deposition brings about oriented growth of cobalt onto the copper substrate and offers the potential to electrochemically tune cobalt deposit with desirable morphology.     

Nature of group Ib metal films deposited on polymer surfaces photooxidized with far-ultraviolet (185 nm) radiation

Solid samples of three polymers (polymethyl methacrylate, polycarbonate, and polyimide), whose surfaces were photooxidized with far-ultraviolet (185 nm) radiation in air, were used as substrates for the deposition of gold, silver, and copper films in vacuo. The electrical conductivities of the films were studied in situ as a function of the film thickness (0–15 nm). At a thickness of 10 nm, silver films showed 10⁴ greater conductivities when deposited on the treated surfaces of all three polymers. Gold films showed no detectable differences between treated and untreated surfaces. Copper behaved similar to gold on PMMA but showed somewhat greater sensitivity (< 20 at 5.4 nm thickness) on photooxidized polyimide. Transmission electron microphotographs of silver films on treated and untreated surfaces showed that photooxidation of the polymer caused the metal to be deposited with better coverage of the surface, i.e., with fewer voids. A partial explanation for the observations would be that photooxidation increases the number of nucleating sites for the metal on the polymer surface. In some way, this must be specific to silver because the effect does not extend to either a more reactive element such as copper or a less reactive element such as gold.     

聚酰亚胺薄膜表面粗糙度的影响因素

 采用热蒸发气相沉积聚合方法（VDP）制备了聚酰亚胺(PI)薄膜,研究了设备、衬底温度、升温过程和单体配比因素对PI薄膜表面形貌的影响。利用干涉显微镜和扫描电镜对薄膜表面形貌进行了分析;利用原子力显微镜测定了薄膜表面粗糙度。结果表明：设定蒸发源-衬底距离为74 cm时可成连续膜;蒸发源采用一段升温和多段升温时,膜表面均方根粗糙度分别为291.23 nm和61.99 nm;采用细筛网可防止原料的喷溅;均苯四甲酸二酐和4,4′-二氨基二苯醚（PMDA和ODA）单体沉积速率比值为0.9∶1时,膜表面均方根粗糙度值可减小至3.30 nm;沉积衬底温度保持30 ℃左右时,膜表面均方根粗糙度为4.01 nm, 随温度的上升,膜表面质量会逐渐变差。     

Deposition of Au/TiO2 film by pulsed laser

Au nanoparticles, which were photoreduced by a Nd:YAG laser in HAuCl₄ solution containing TiO₂ colloid and accompanied by the TiO₂ particles, were deposited on the substrate surface. The film consisting of Au/TiO₂ particles was characterized by the absorption spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The adhesion between the film and substrate was evaluated by using adhesive tape test. It was found that the presence of TiO₂ dramatically enhanced the adhesion strength between the film and the substrate, as well as the deposition rate of film. The mechanism for the deposition of Au/TiO₂ film was also discussed.     

Synthesis of TiN thin films by a new combined laser/sol-gel processing technique

In this work a novel method for synthesising TiN coatings is reported. A high-power diode laser at different powers and traverse speeds was applied to a mild steel substrate, coated with a slurry of titania sol-gel, urea and graphite. The reaction chemical thermodynamics was investigated to estimate the compositions, temperature range, and the required reaction enthalpy for producing TiN. A one-dimensional heat transfer model was used to optimise the processing parameters. Surface morphology and microstructure of the deposited coatings and substrate surface layers were examined using optical microscopy, scanning electron microscope, and field emission gun scanning electron microscope which reveals deposition of very thin layer about 0.3 μm of pure TiN and the presence of sub-micron crystalline structure of TiN forming a metal matrix composite inter-layer with the substrate below the film which suggest a good metallurgically bonding with the substrate. Chemical composition was determined by energy dispersive X-ray analysis. The phases were identified by X-ray diffraction which confirms the synthesis of TiN film for all the samples. Results of nano-hardness measurements revealed a hardness value of the order of 22-27 GPa.     

高脉冲功率能量PLD法制备MgZnO薄膜中的沉积机理

用PLD法成功制备了一系列高质量的MgZnO薄膜。实验中发现高脉冲能量沉积薄膜的结构和发光特性随基片温度的变化规律与低脉冲能量下的结果不一样:基片在室温时高脉冲能量制备薄膜的XRD峰的半峰全宽比高基片温度时的结果相对更小;AFM显示其颗粒变大,柱状生长突出;PL谱紫峰与绿峰强度比最大,结晶质量反而提高。另一方面,与低脉冲能量时相反,增大氧气压强后高脉冲能量沉积的薄膜XRD半峰全宽变窄。结合实验现象和表征,合理解释了高脉冲能量沉积的机理。室温制备高质量MgZnO薄膜的PLD沉积机理对于以后在柔性衬底上沉积薄膜的研究有重要的参考价值。     

基体对应力诱导的纳米晶W膜开裂行为的影响

采用磁控溅射方法同时在Si(100)和聚酰亚胺(PI)基体上沉积W膜,对比研究不同基体约束对纳米晶W膜微观结构及应力诱导的开裂行为的影响.结果发现,在两种基体上W膜的裂纹形态明显不同.在Si基体上W膜的裂纹呈楔形,而在PI基体上W膜的裂纹呈半圆柱形凸起于薄膜表面.这种裂纹形态的差异源于两种基体上W膜的变形机理不同.在刚性Si基体上,W膜的裂纹扩展是通过晶粒平面内的转动实现的,而在柔性PI基体上W膜裂纹扩展是通过排列晶粒在平面内、外的转动协调完成的.分析表明,两种截然不同的开裂行为与不同基体上薄膜内应力的变 关键词： W膜 残余应力 裂纹 晶粒     

A facile method for preparing highly conductive and reflective surface-silvered polyimide films

A novel method was developed for the preparation of reflective and electrically conductive surface-silvered polyimide (PI) films. The polyimide films were functionalized with poly(dopamine), simply by dipping the PI films into aqueous dopamine solution and mildly stirring at room temperature. Electroless plating of silver was readily carried out on the poly(dopamine) deposited PI (PI-DOPA) surface. The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results show that the PI-DOPA surfaces were successfully deposited with ploy(dopamine) and were ready for electroless deposition of silver. The poly(dopamine) layer was used not only as the chemi-sorption sites for silver particles during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The as-prepared silvered PI films show high conductivity and reflectivity, with a surface resistance of 1.5 Ω and a reflectivity of 95%, respectively.