Ion bombardment-induced high orientation of Al/Ti films for surface acoustic wave device applications

Al/Ti films were deposited on 128° Y-X LiNbO₃ substrates by electron-beam (e-beam) deposition. Low-energy Ar ion beam bombardment was employed during the Ti underlayer deposition. Influence of low-energy beam bombardment on the texture of Al/Ti films was investigated by x-ray diffraction (XRD) analysis. It was found that Al films deposited on Ar-ion bombarded Ti underlayers possessed excellent (111) texture. With the textured Al/Ti films, a 2.3-GHz range image-impedance connection surface acoustic wave (SAW) filter was successfully fabricated.     

Growth of Single‐Walled Carbon Nanotubes from Microcontact‐Printed Catalyst Patterns on Thin Si3N4 Membranes

Single‐walled carbon nanotubes have been grown by chemical vapor deposition from methane and hydrogen on catalyst patterns prepared by microcontact printing on 20 nm thick silicon nitride substrates. A higher yield of single‐walled carbon nanotubes was obtained by the simple expedient of introducing hydrogen during deposition. Based on atomic force microscopy and transmission electron microscopy measurements, we found that high‐quality single‐walled carbon nanotubes with a broad diameter distribution were obtained.     

Structural and interfacial properties of large area n-a-Si:H/i-a-Si:H/p-c-Si heterojunction solar cells

Growth of hydrogenated amorphous silicon in a doping inversed silicon heterojunction solar cell (n-a-Si:H/i-a-Si:H/p-c-Si) interface was investigated by High Resolution Transmission Electron Microscopy (HR-TEM), Spectroscopic Ellipsometry (SE), Fourier Transform Infrared Attenuated Total Reflection spectroscopy (FTIR-ATR) and current–voltage (I–V) measurements. Effective Medium Approximation (EMA) to the SE was used to describe breakage of epi-Si and evolution of mixture of microcrystalline and amorphous phases. Fabricated silicon heterojunction solar cells were characterized by dark and light I–V measurements at Standard Test Conditions. By improving the cleaning and deposition conditions, solar cells with 9.2% efficiency over 72 cm² total active area were obtained on p-type c-Si wafers.     

Structural and photoelectrical characteristics of Si/6H-SiC heterojunctions prepared by hot-wall chemical vapor deposition

Based on a potential application for the Si/SiC heterojunction to realize light control of SiC devices, structures and electrical properties of boron-doped silicon layer deposited on the n-type 6H-SiC substrate by hot-wall chemical vapor deposition were investigated in this paper.X-ray diffraction analysis and scanning electronic microscopy were used to characterize the crystal structure and morphology of the deposited silicon layer. Results of I–V and C–V measurements indicated that the heterojunction was abrupt manifesting obvious p–n junction properties. During the I–V measurement, the Si/SiC heterojunction developed a remarkable photovoltaic effect under illumination condition.     

One-pot synthesis of ZnO/reduced graphene oxide nanocomposite for supercapacitor applications

ZnO/reduced graphene oxide (RGO) nanocomposite films were prepared by the sol–gel deposition method using a combination of zinc acetate and graphite. The solution derived composite films were extensively characterized using high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–visible spectroscopy, photoluminescence emission measurements, and four probe measurements. It was found that a highly transparent film with low resistivity could be obtained with the addition of a small amount of RGO into the deposition precursor. The results also showed that the sintering temperature reduces the resistivity and transparency of the films. XRD measurements revealed that films sintered >500 °C exhibit additional peaks, and suggest nucleation of different phases of the films. As a demonstration, the ZnO/RGO composite was integrated into a supercapacitor, and the resulting energy storage performance was tested.     

碳纳米尖端形成的理论分析

用CH4,H2和NH3为反应气体,利用等离子体增强热丝化学气相沉积在沉积有碳膜的Si衬底上制备了碳纳米尖端.用原子力显微镜和微区Raman光谱仪对碳膜进行了表征,结果表明,碳膜是粗糙不平的非晶碳膜.用扫描电子显微镜研究了不同条件下生长的碳纳米尖端,结果表明,碳纳米尖端的形成与离子的轰击有关.根据实验结果,利用离子沉积和溅射等有关的理论建立了碳纳米尖端形成的三维理论模型,并利用该模型对实验结果进行了解释,它将对控制碳纳米尖端的生长和应用研究有很大的意义.     

用弹道电子发射显微术研究超薄金属硅化物/硅肖特基接触

采用弹道电子发射显微术 ( BEEM)技术对超薄 Pt Si/Si、Co Si2 /Si肖特基接触特性进行了研究 ,并与电流 -电压 ( I- V)及电容 -电压 ( C- V)测试结果进行了对比 .研究了 Ar离子轰击对超薄Pt Si/n- Si肖特基接触特性的影响 .BEEM、I- V/C- V技术对多种样品的研究结果表明 ,I- V/C- V测试会由于超薄硅化物层串联电阻的影响而使测试结果产生严重误差 ;BEEM测试则不受影响 .随着离子轰击能量增大 ,肖特基势垒高度降低 ,且其不均匀性也越大 .用 BEEM和变温 I- V对超薄 Co Si2 /n- Si肖特基二极管的研究结果表明 ,变温 I- V测试可在一定程度上获得肖特基势垒     

离子束增强沉积法制备二氧化铪薄膜

利用离子束增强沉积(IBED)技术在硅衬底上沉积得到50nm的二氧化铪薄膜.卢瑟福背散射(RBS)的结果指出样品表面有过量氧元素存在.X射线光电子能谱(XPS)显示退火前后薄膜内部化学键没有变化.透射电子显微镜(TEM)表明界面处有非晶铪氧硅化合物生成.电子衍射(ED)显示所制备的二氧化铪薄膜呈现长程无序、区域有序的多晶态.实验为HfO2作为高k电介质在集成电路制造中的应用提供了一种简单有效的方法.     

Deposition,opto-electronic and structural characterization of polymorphous silicon thin films to be applied in a solar cell structure

In this study we analyze the optoelectronic properties and structural characterization of hydrogenated polymorphous silicon thin films as a function of the deposition parameters. The films were grown by plasma enhanced chemical vapor deposition (PECVD) using a gas mixture of argon (Ar), hydrogen (H₂) and dichlorosilane (SiH₂Cl₂). High-resolution transmission electron microscopy images and Raman measurements confirmed the existence of very different internal structures (crystalline fractions from 12% to 54%) depending on the growth parameters. Variations of as much as one order of magnitude were observed in both the photoconductivity and effective absorption coefficient between the samples deposited with different dichlorosilane/hydrogen flow rate ratios. The optical and transport properties of these films depend strongly on their structural characteristics, in particular the average size and densities of silicon nanocrystals embedded in the amorphous silicon matrix. From these results we propose an intrinsic polymorphous silicon bandgap grading thin film to be applied in a p–i–n junction solar cell structure. The different parts of the solar cell structure were proposed based on the experimental optoelectronic properties of the pm-Si:H thin films studied in this work.     

AlN薄膜室温直接键合技术

采用离子束增强沉积技术在 10 0 mm硅片上制备大面积均匀 Al N薄膜 ,原子力显微镜 (AFM)显示其表面平整光滑 ,均方根粗糙度 (RMS)为 0 .13nm ,满足直接键合的需要 .同时 ,采用智能剥离技术成功实现了室温下 Al N与注氢硅片的直接键合 ,形成了以 Al N薄膜为埋层的 SOI结构 ,即 Al N上的硅结构 (SOAN) .用扩展电阻、卢瑟福背散射 -沟道、剖面透射电镜等技术分析了所形成的 SOAN结构.     

Thermal stability of tantalum nitride diffusion barriers for Cu metallization formed using plasma immersion ion implantation

Plasma immersion ion implantation (PIII) technique was employed to form Tantalum nitride diffusion barrier films for copper metallization on silicon. Tantalum coated silicon wafers were implanted with nitrogen at two different doses. A copper layer was deposited on the samples to produce Cu/Ta(N)/Si structure. Samples were heated at various temperatures in nitrogen ambient. Effect of nitrogen dose on the properties of the barrier metal was investigated by sheet resistance, X-ray diffraction and scanning electron microscopy measurements. High dose nitrogen implanted tantalum layer was found to inhibit the diffusion of copper up to 700 °C.     

Evaluating nanotribological behavior of annealing Si0.8Ge0.2/Si films

In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load.Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration.     

背面多孔硅对SIMOX中铜杂质的吸除作用

在SIMOX材料的背面成功地制备了多孔硅层,再在正面故意注入1×1015cm-2剂量的铜杂质。经900℃退火,二次离子质谱（SIMS）测试表明钢杂质能穿过理层SiO2并在背面多孔硅处富集。用剖面投射电子显微镜（XTEM）分析了埋层SiO2和背面多孔硅层的微观结构,背面多孔硅层及其多孔硅层同硅衬底之间“树技状”的过渡区被认为是铜杂质有效的吸除中心。     

Light emission from Si/SiO2 superlattices fabricated by RPECVD

Si/SiO₂ superlattices that exhibit intense luminescence properties were fabricated by remote plasma enhanced chemical vapor deposition. (RPECVD) and subsequent rapid thermal annealing for silicon crystallization. The effects of charge carrier confinement like blue shifting of the PL spectra and intensity increase with decreasing Silicon quantum well thickness are observed in low temperature photoluminescence experiments. The Si/SiO₂ interface quality is calculated from capacitance voltage (CV) measurements on metal oxide semiconductor teststructures showing excellent layer and Si/SiO₂ interface properties. The Si crystallization process is investigated and analyzed by Raman and transmission electron microscopy. Decreasing the Si quantum well thickness to 2 nm leads to light emission at room temperature.     

HF溶液中铜离子在硅片表面沉积的研究

研究了溶液中的铜离子在硅片表面的沉积情况,尝试采用几种螯合剂来减少铜在硅片表面的沉积.GFAAS的测试结果表明,HF稀溶液中加入少量螯合剂,均可以使硅片表面的金属Cu的沉积量显著减少,但不同的螯合剂效果不同,而且与溶液中螯合剂与铜形成的络合物稳定性质并不完全一致.加入螯合剂后,铜离子与螯合剂不仅在溶液中反应,而且在硅片表面形成竞争吸附,对铜离子在硅片表面的沉积量影响较大.     

High quality silicon nitride deposited by Ar/N2/H2/SiH4 high-density and low energy plasma at low temperature

The high-quality PECVD silicon nitride has been deposited by high-density and low-ion-energy plasma at 400 °C and the effect of the process parameters, such as silane and nitrogen flow rate, pressure, on its structure and electrical properties has been investigated. The experimental results show that silane flow rate is the most sensitive parameter for determining deposition rate and N/Si atomic ratio of silicon nitride in the range of process parameters employed. The change of nitrogen flow rate leaded to slightly change in deposition rate, however, it effects significantly on the refractive index or densification of silicon nitride. With the addition of hydrogen gas in plasma, the hysteresis of C-V characteristics of MIS structure decreases from 0.4 to 0.1 V. The moderate increment of ion energy makes further reduction in the hysteresis of C-V characteristics of MIS from 0.1 V to below 0.05 V. The interface trap density of 6.2×10¹⁰ (ev⁻¹ cm^-2), deduced from the high frequency and quasistatic C-V characteristics of the MIS structure, is about the same as that of LPECVD silicon nitride deposited at the range of 750-850 °C. The stoichiometric silicon nitride of excellence electric and structural properties is obtained by Ar/N₂/H₂/SiH₄ high-density and low ion energy plasma.     

DC isolation and RF dissipation loss of coplanar waveguide on GaAs multi conductive Layers bombarded by H/sup +/ and Fe/sup +/ ions

This letter explores the dc isolation and radio frequency (RF) dissipation loss of coplanar waveguide (CPW) lines of H/sup +/ and Fe/sup +/ ion bombarded GaAs multi conductive epitaxial layers. It is demonstrated that although a sheet resistivity as high as 10/sup 8/ /spl Omega/sq has been achieved by ion bombardment, showing excellent dc isolation, the RF dissipation loss of gold metallized CPW lines on the bombarded multi conductive epitaxial layers are higher than that on a semi-insulating GaAs substrate, especially at higher frequencies (0.5 dB/cm higher at 50 GHz). This is probably caused by deep level trappings due to the ion bombardment.     

Fabrication of submicron junctions-proximity rapid thermaldiffusion of phosphorus, boron, and arsenic

Various techniques used in fabrication of deep submicron junctions are reviewed with respect to their advantages and disadvantages in silicon very large scale integration (VLSI) circuits technology. Proximity rapid thermal diffusion is then presented as an alternative process which results in very shallow junctions with high dopant concentrations at the surface. The feasibility of Si doping with B, P, and As for both planar and 3-D structures such as trench capacitors used in high density DRAM memories is shown based on sheet resistance measurements, secondary ion mass spectroscopy and scanning electron micrographs. Retardation effect of arsenic diffusion similar to the well known inhibition of silicon or SiO₂ deposition in chemical vapor deposition (CVD) processes is identified and discussed     

Boron-doped silicon film as a recombination layer in the tunnel junction of a tandem solar cell

Boron-doped hydrogenated silicon films with different gaseous doping ratios (B2H6/SiH4) were deposited in a plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure of the films was investigated by atomic force microscopy (AFM) and Raman scattering spectroscopy. The electrical properties of the films were characterized by their room temperature electrical conductivity (σ) and the activation energy (Ea). The results show that with an increasing gaseous doping ratio, the silicon films transfer from a microcrystalline to an amorphous phase, and corresponding changes in the electrical properties were observed. The thin boron-doped silicon layers were fabricated as recombination layers in tunnel junctions. The measurements of the Ⅰ-Ⅴ characteristics and the transparency spectra of the junctions indicate that the best gaseous doping ratio of the recombination layer is 0.04, and the film deposited under that condition is amorphous silicon with a small amount of crystallites embedded in it. The junction with such a recombination layer has a small resistance, a nearly ohmic contact, and a negligible optical absorption.     

Electroless Cu deposition process on TiN for ULSI interconnect fabrication via Pd/Sn colloid activation

In this study, (100)-orientation silicon wafer coated with TiN barrier is catalyzed by a Pd/Sn colloid, which serves as an activator for electroless copper deposition. After activation, electroless deposition of Cu occurs on the catalytic surface. The coverage of the Cu deposit reaches 100% and the adsorptive amount of Pd is greatly increased by the conditioning process. The correlation between deposition rate, resistivity, morphology, crystal structure, and composition of the deposit when varying the temperature of the plating bath is discussed. The deposition rate of Cu is monitored by both the electrochemical method and the profilometer (α-step), while the other properties of the deposit are measured by four-point probe, scanning electron microscopy (SEM), x-ray diffraction (XRD), and Auger electron microscopy (AES). Deposition at 70°C is favorable due to the higher deposition rate, lower resistivity, less impurities, and more preferred orientation in the crystal structure than that at lower temperature. Problems regarding adhesion and high resistivity can be greatly mitigated via 400°C thermal annealing. The resistivity of Cu can be reduced to 2.2 μΩcm. Moreover, trenches of 1 μm and 0.25 μm on patterned wafer have been successfully filled by electroless deposition of Cu with the aid of surfactant C12.