Impact of the Cu-based substrates and catalyst deposition techniques on carbon nanotube growth at low temperature by PECVD

This article reports on carbon nanotubes (CNT) grown on TiN/Cu stacks by plasma enhanced chemical vapor deposition (PECVD) at 450 °C. Ni catalyst was deposited by two techniques - physical vapor deposition (PVD) and electrochemical deposition (ECD). First, the influence of the catalyst thickness and the catalyst deposition technique on grown CNTs is investigated. Second, the enhancement of the CNTs growth by use of electrodeposited catalysts is emphasized.     

IC表面钝化PECVD工艺的计算机模拟

本文介绍了一种新的工艺研究途径－神经网络反向传播算法（ＢＰ算法），并对其网络学习收敛速度的加快进行了讨论，取得了较好的效果；利用改进的神经网络ＢＰ算法，我们通过建立ＩＣ表面钝化工艺的神经网络模型，对ＩＣ表面钝化工艺进行了计算机模拟，精确地预报了实验结果并得到了相关工艺条件与钝化介质膜特性的关系曲线，所编写的神经网络应用程序已用Ｃ语言在计算机上得到了实现。     

ZnO Thin Film, Device, and Circuit Fabrication using Low-Temperature PECVD Processes

We report undoped ZnO films deposited at low temperature (200°C) using plasma-enhanced chemical vapor deposition (PECVD). ZnO thin-film transistors (TFTs) fabricated using ZnO and Al₂O₃ deposited in situ by PECVD with moderate gate leakage show a field-effect mobility of 10 cm²/V s, threshold voltage of 7.5 V, subthreshold slope <1 V/dec, and current on/off ratios >10⁴. Inverter circuits fabricated using these ZnO TFTs show peak gain magnitude (dV _out/dV _in) ~5. These devices appear to be strongly limited by interface states and reducing the gate leakage results in TFTs with lower mobility. For example, ZnO TFTs fabricated with low-leakage Al₂O₃ have mobility near 0.05 cm²/V s, and five-stage ring-oscillator integrated circuits fabricated using these TFTs have a 1.2 kHz oscillation frequency at 60 V, likely limited by interface states.     

低应力PECVD SiC晶圆级薄膜封装新技术

为了解决MEMS封装过程中易对微致动件造成损伤的问题,提出了一种低成本、与CMOS工艺兼容的晶圆级薄膜封装技术,用等离子体增强化学气相淀积(PECVD)法制备的低应力SiC作为封装和密封材料。此材料的杨氏模量为460 GPa,残余应力为65 MPa,可使MEMS器件悬浮时封装部位不变形。与GaAs,Si半导体材料相比,SiC具有较佳的物理稳定性,较高的杨氏模量等性能优势。将PECVD薄膜封装技术用于表面微结构和绝缘膜上Si(SOI)微结构部件(如射频开关、微加速度计等)封装中,不仅减小了封装尺寸,降低了芯片厚度,简化了封装工艺,而且封装芯片还与CMOS工艺兼容。较之晶圆键合封装方式,此晶圆级薄膜封装成本可降低5%左右。     

PECVD沉积双层SiNx对太阳电池性能的影响

提出了一种简单有效的制备双层SiNx薄膜的方法,其薄膜具有良好的减反射钝化特性。采用等离子体增强化学气相沉积(PECVD)的方法,通过控制SiH4和NH3气体流量比,在p型多晶硅衬底上生长单层及双层SiNx膜。随后使用薄膜测试分析仪测量了薄膜的厚度、折射率及反射率,并用Semilab WT-2000测量少数载流子寿命,通过测量量子效率,对单、双层膜电池进行了比较。实验结果表明:相比单层减反射钝化膜,采用双层SiNx膜,少数载流子寿命可以得到更好的改善,开路电压可提高约2 mV,短路电流可提高约40 mA,电池效率能提高0.15%。     

PECVD法制备纳米晶硅薄膜的研究进展

简要介绍了纳米晶硅薄膜的微结构表征方法,重点讨论了PECVD制备方法中工艺参数对薄膜结构的影响,并探讨了氢在薄膜形成和生长中的作用。通过优化氢稀释率、衬底温度、反应气压、激励功率和激发频率等工艺参数可提高纳米晶硅薄膜的晶化率并改善薄膜质量。结合喇曼光谱、X射线衍射谱、傅里叶红外光谱和高分辨透射电镜等表征方法可深入研究薄膜形成机理,对进一步探索薄膜光电特性有重要意义。分析了等离子体化学气相沉积(PECVD)制备方法中各工艺参数对薄膜质量和沉积速率的影响,指出其存在的问题,并探寻了今后的研究方向。     

Analysis of the infrared transmission data of hydrogenated amorphous silicon film fabricated by high rate PECVD

The optical properties of hydrogenated amorphous silicon thin films prepared by a new thermocatalytic plasma enhanced chemical vapor deposition (PECVD) method are here reported for the first time. The transmission spectrum of the film, deposited at a rate of 1.5 nm/s, was measured between 500 and 1100 nm. The envelopes of the transmission spectrum interference maxima and minima were analyzed to reveal the absorption coefficient α(λ@#@), the refractive indexn(λ), the average thickness of the film (791 nm) and the variation of the thickness (11.4 nm), using an analysis which takes into account film inhomogeneity. The modified Newton's method of numerical analysis was used to obtain the optical parameters. The optical band gap ε₀} was determined to be 1.69 eV from the absorption coefficient spectrum, commensurate with values quoted for lower deposition rate PECVD films. The value for ε₀}, the small variation of the film thickness, and a value for the defect density of 3.7 x 10¹⁵}cm^-3} determined for similar material in other work indicate that the thermocatalytic PECVD method can produce acceptable quality films at a high deposition rate.     

淀积参数对PECVD氮化硅薄膜力学特性的影响

等离子增强化学气相淀积(PECVD)法制备的氮化硅薄膜具有沉积温度低、生长速率高和残余应力可调节等特点,研究其力学特性对研制MEMS器件和系统具有重要意义。采用HQ-2型PECVD淀积台,在沉积温度为350℃,NH3流量为30cm3/min的条件下,通过改变氩气稀释至5%的SiH4流量和射频功率大小,制备了具有压应力、微应力和张应力的多种氮化硅薄膜样品。采用纳米压痕仪Nanoidenter-G200对淀积薄膜的杨氏模量和硬度进行测试,结果表明,在较小的SiH4流量和较高的射频功率条件下,淀积的氮化硅薄膜具有更高的杨氏模量和硬度。     

Low temperature plasma enhanced chemical vapor deposition of silicon oxide films using disilane and nitrous oxide

Silicon oxide films have been deposited between room temperature and 300°C using disilane and nitrous oxide by plasma enhanced chemical vapor deposition. Film deposition was investigated as a function of the gas flow ratio of nitrous oxide to disilane, the substrate temperature, the total gas flow rate, the radio frequency discharge power, and the process pressure. The stoichiometric SiO₂ films were obtained when the gas ratio of nitrous oxide to disilane was in the range of 50-150. The deposition was found to be nearly temperature independent indicating the mass transport limited regime.     

Characteristics of PECVD grown tungsten nitride films as diffusion barrier layers for ULSI DRAM applications

We have developed tungsten nitride (W-Nitride) films grown by plasma enhanced chemical vapor deposition (PECVD) for barrier material applications in ultra large scale integration DRAM devices. As-deposited W-Nitride films show an amorphous structure, which transforms into crystalline, β-W₂N and α-W phases upon annealing at 800°C. The resistivity of the as-deposited films grown at the NH₃/WF₆ gas flow ratio of 1 is about 160 μω-cm, which decreases to 50 μω-cm after an rapid thermal annealing treatment at 800°C. In the contact holes with the size of 0.35 μm and aspect ratio of 3.5, the bottom step coverage of the tungsten nitride films is about 60%, which is about three times higher than that of collimated-TiN films. We obtained contact resistance and leakage current with the tungsten nitride barrier layer comparable to those with conventional collimated TiN films. The contact resistance and leakage current are stable upon thermal stressing at 450°C up to 48 h.     

RF-PECVD法研究碳纳米管的生长特性

采用射频等离子体增强化学气相沉积(RF-PECVD),以Fe作为催化剂,在Si基片上生长了碳纳米管(CNT),采用扫描电子显微镜(SEM),高分辨透射电子显微镜(HR TEM)以及显微Raman光谱等对制备的CNT的形貌及结构进行了表征.结果表明:700℃和800℃温度下生长的CNT均取向无序、弯曲缠结,由整齐排列的圆...     

Deposition of highly efficient microcrystalline silicon solar cells under conditions of low H2 dilution: the role of the transient depletion induced incubation layer

This paper addresses the plasma deposition of highly efficient microcrystalline silicon (μc‐Si:H) p‐i‐n solar cells under conditions of high SiH₄ utilization and low H₂ dilution. It was established that the transient depletion of the initially present SiH₄ source gas induces the formation of an amorphous incubation layer that prevents successful crystallite nucleation in the i‐layer and leads to poor solar cell performance. The effect of this transient depletion induced incubation layer on solar cells was made visible through dedicated solar cell deposition series and selected area electron diffraction measurements. Applying a gas flow procedure at plasma ignition it was succeeded to prepare state‐of‐the‐art μc‐Si:H material and solar cells under low hydrogen dilution conditions, highlighted by μc‐Si:H solar cells of up to 9·5% efficiency prepared using an undiluted source gas flow consisting solely of SiH₄. Copyright © 2007 John Wiley & Sons, Ltd.     

Preparation of PbTiO3 thin films by plasma enhanced MOCVD and the effect of rapid thermal annealing

Dielectric PbTiO₃-thin films were prepared on p-Si(100) substrate by plasma enhanced metalorganic chemical vapor deposition using high purity Ti(O-i-C₃H₇)₄, Pb(tmhd)₂, and oxygen. As-deposited films were post-treated by rapid thermal annealing method, and the effect of annealing was examined under various conditions. The deposition process was controlled by mixed-control scheme at temperatures lower than 350°C, but controlled by heterogeneous surface reaction at temperatures greater than 350°C. The as-deposited films showed PbO structure at 350∼400°C, but (100) and (101) PbTiO₃ orientations started to appear at 450°C. The deposition rate was increased with rf power due to the enhanced dissociation of Ti and Pb precursors. It was found that the concentration of oxygen plays an important role in crystallization of PbTiO₃ during the rapid thermal annealing. A linear relationship was obtained between the dielectric constant of PbTiO₃ films and the annealing temperature. However, the surface roughness and leakage current density increased mainly due to the defects caused by volatilization of lead and the interface layer formed during the high temperature annealing.     

Growth and characterization of heavily carbon doped InGaAs lattice matched to InP by LP-MOCVD using liquid CCI4

The growth of heavily carbon dopedp-InGaAs (~6.5xl0¹⁹cm^-3) lattice-matched to InP is reported. Growth is achieved by low pressure metalorganic chemical vapor deposition (LP-MOCVD) using all methyl metalorganic sources and liquid CC1₄. The impact of growth temperature and CC1₄ flow rates on growth rate reduction and alloy compositional change was investigated. Post-growth isothermal and isochronal annealing experiments were performed on the carbon doped InGaAs layers and a quantitative analysis of carrier activation is presented using Hall and secondary ion mass spectroscopy measurements. Reduced self-compensation by carbon displacement from indium to arsenic site, as well as, reduced hydrogen passivation are suggested as possible mechanisms responsible for carrier activation upon thermal annealing.