Low-K介质与Cu互连技术在新型布线系统中的应用前景

集成电路(IC)的快速发展对ULSI布线系统提出了更高的要求。本文通过对ULSI互连布线系统的分析,在介绍了ULSI新型布线系统的同时,尝试预测互连技术的趋势走向,同时展望Low-K介质与Cu互连技术在新型布线系统中的应用前景。

low-k给我们带来了什么？

前文谈到随着芯片集成度的提高，阻容迟滞引起的信号传播延迟、线问干扰以及功耗等成为不可回避的问题而low-k似乎可以改善这些情况。那么，因被应用于ATI的图形芯片和Intel的Prescott核心P4而被炒得火热的low-k，是否真是一剂可解决上述问题的灵丹妙药呢？

多孔Low-k材料各向异性特性声表面波测量模型

声表面波技术可无损测量纳米多孔介电薄膜材料的机械特性参数.采用横观各向同性模型表征二维周期性多孔薄膜的结构特性,推导了表面波在周期性纳米多孔薄膜/硅基底结构中的传播模型.通过编程计算数值算例,得到了薄膜各向异性结构特性及弹性模量对表面波色散曲线的影响.结果表明,纳米通孔方向与传播方向间的角度差会对色散曲线产生明显影响,在垂直于通孔的传播方向不能测出弹性模量E′.最后给出了有助于改善测量精度的措施.此模型可用于纳米多孔低介电常数材料各向异性特性测试实验.

Influence of roughness on the detection of mechanical characteristics of low-k film by the surface acoustic waves

The surface acoustic wave （SAW） technique is a precise and nondestructive method to detect the mechanical charac- teristics of the thin low dielectric constant （low-k） film by matching the theoretical dispersion curve with the experimental dispersion curve. In this paper, the influence of sample roughness on the precision of SAW mechanical detection is inves- tigated in detail. Random roughness values at the surface of low-k film and at the interface between this low-k film and the substrate are obtained by the Monte Carlo method. The dispersive characteristic of SAW on the layered structure with rough surface and rough interface is modeled by numerical simulation of finite element method. The Young＇s moduli of the Black DiamondTM samples with different roughness values are determined by SAWs in the experiment. The results show that the influence of sample roughness is very small when the root-mean-square （RMS） of roughness is smaller than 50 nm and correlation length is smaller than 20 μm. This study indicates that the SAW technique is reliable and precise in the nondestructive mechanical detection for low-k films.

Effect of F doping on capacitance-voltage characteristics of SiCOH low-k films metal-insulator-semiconductor

This paper investigates the capacitance-voltage （C-V） characteristics of F doping SiCOH low dielectric constant films metal-insulator-semiconductor structure. The F doping SiCOH films are deposited by decamethylcyclopentasilox-ane [DMCPS） and trifluromethane （CHF3） electron cyclotron resonance plasmas. With the CHF3/DMCPS flow rate ratio from 0 to 0.52, the positive excursion of C-V curves and the increase of fiat-band voltage VFB from -6.1 V to 32.2V are obtained. The excursion of C-V curves and the shift of VFB are related to the change of defects density and type at the Si/SiCOH interface due to the decrease of Si and O concentrations, and the increase of F concentration. At the CHF3/DMCPS flow rate ratio is 0.12, the compensation of F-bonding dangling bond to Si dangling bond leads to a small VFB of 2.0V.

C_2F_6 /O_2 /Ar Plasma Chemistry of 60 MHz/2 MHz Dual-Frequency Discharge and Its Effect on Etching of SiCOH Low-k Film

This work investigated C2F6/O2/Ar plasma chemistry and its effect on the etching characteristics of SiCOH low-k dielectrics in 60 MHz/2 MHz dual-frequency capacitively coupled discharge. For the C2F6/Ar plasma, the increase in the low-frequency （LF） power led to an increased ion impact, prompting the dissociation of C2F6 with higher reaction energy. As a result, fluorocarbon radicals with a high F/C ratio decreased. The increase in the discharge pressure led to a decrease in the electron temperature, resulting in the decrease of C2F6 dissociation. For the C2F6/O2/Ar plasma, the increase in the LF power prompted the reaction between 02 and C2F6, resulting in the elimination of CF3 and CF2 radicals, and the production of an F-rich plasma environment. The F-rich plasma improved the etching characteristics of SiCOH low-k films, leading to a high etching rate and a smooth etched surface.

Effect of CHF_3 Plasma Treatment on the Characteristics of SiCOH Low-k Film

The characteristics of SiCOH low dielectric constant film treated by a trifluromethane （CHF3） electron cyclotron resonance （ECR） plasma was investigated. The flat-band voltage VFB and leakage current of the Cu/SiCOH/Si structure, and the hydrophobic property of the SiCOH film were obtained by the measurements of capacitance-voltage, current-voltage and water contact angle. The structures of the SiCOH film were also analyzed by Fourier transform infrared spectroscopy and atomic force microscopy. The CHF3 plasma treatment of the SiCOH film led to a reduction in both the fiat-band voltage VFB shift and leakage current of the Cu/SiCOH/Si structure, a decrease in surface roughness, and a deterioration of the hydrophobic property. The changes in the film＇s characteristics were related to the formation of Si-F bond, the increase in Si-OH bond, and the C：F deposition at the surface of the SiCOH film.

Effects of O_2 Plasma Treatment on the Chemical and Electric Properties of Low-k SiOF Films

With the progress of ULSI technology, materials with low dielectric constant are required to replace Si02 film as the interlayer to scale down the interconnection delay. Fluorinated Si oxide thin films (SiOF) are a promising material for the low dielectric constant and the process compatibility in existing technology. However, SiOF films are liable to absorb moisture when exposed to air. By treating the SiOF films with O2 plasma, it was found that the moisture resistibility of SiOF films was remarkably improved. The mechanism of the improvement in stability of dielectric constant was investigated. The results show that: 1) F atoms dissociated from the films and the bond angle of Si-O-Si decreased. 2) The plasma treatment enhanced the strength of Si-F bonds by removing unstable =SiF2 structures in the films. Resistibility of SiOF films in moisture was improved.

The Fabrication and Characterisation of Low-k Cordierite-Based Glas s-Ceramics by Tape Casting

Cordierite is a promising low-k material in mi cr oelectronic and packaging industries. When it is co-fired with the metal for re alising the multilayer circuits, temperature should be low enough to prevent the melting and/or oxidising of the metal. However, this temperature is usually too low to sinter cordierite. Low melting point glass, therefore, is added to the s toichiometric cordierite to lower the sintering temperature through a liquid-si ntering process. In this research work, cordierite-based glass ceramics tapes were prepared by t ape casting from suspensions containing different solids loading and different m ean particle sizes. The optimal experimental conditions for obtaining homogenous green tapes were determined by varying the type and concentration of dispersant s and binders, the solids loading as well as the particle sizes of both cordieri te and glass. Scanning electron microscopy (SEM) and Hg porosimetry were used to characterise the green tapes. The results showed that high values of solids vol ume fractions and of the size ratio between the mean particle sizes of glass and cordierite powders favour the obtaining of homogeneous and high dense substrate s. The dielectric constant of the sintered bodies at 1 100 ℃ was around 5 and t he dissipation factor was about 0.01 at 1 MHz.

日本油脂开发low-k印刷电路板

日本油脂开发成功了相对介电常数仅2．5的印刷电路板材料，据称还能实现曲面等立体形状的印刷电路板。2005年秋将以双面贴铜层压板的形式开始提供样品。在开发过程中，日本TDK在印刷电路板的性能测试中提供了协作。这次开发的是采用烯烃类热可塑树脂的底板材料。2GHz时的相对介电常数为2．5，

用于集成电路铜互连工艺的Low-K材料研究

随着集成电路的快速发展,集成电路互连成为限制芯片性能的主要因素,而降低介质层的介电常数是解决互连问题的重要途径。本文综述了用于集成电路铜互连工艺的低介电(Low-K)材料的制备方法及Low-K候选材料。等离子体增强化学气相沉积和旋涂沉积法可根据各自的优缺点适用于不同情况中,low-k候选材料有着各自优缺点,周期性介孔有机硅(PMO)材料是目前应用较为广泛的low-k材料。

半导体器件微缩化 铜导线与Low-K为关键所在

随着器件的关键尺寸(Critical Dimension)愈来愈小及导线层数的急剧增加,电阻/电容时间延迟(RC Time Delay)将严重影响整体电路的运行速度。为了改善随着金属联机线宽缩小所造成的时间延迟以及电子迁移可靠性问题,选择比铝合金更低的电阻率与更高的抗电子迁移破坏能力的铜导线材料,替换原来的铝合金金属是必要的。

IC芯片里的绝缘胶布：Low-K技术

在摩尔定律的催化下，半导体制程技术日新月异地发展，从当初的8080处理器到现在的Prescott，芯片中的晶体管集成数量以不可思议的速度增长着，在给我们带来高速高效的同时也不可避免地产生了很多问题，譬如发热量太、制造工艺要求高质选择更为挑剔。而在所有众多须要解决的问题当中有一个比较尖——这就是由于电器元件相互之间的干扰而造成的芯片性能下降。随着芯片的不断发展，科学家们也一直在寻找各种方法来解决这个矛盾，如使用二氧化硅隔离，使用氟化硅玻璃等，但是在芯片集成度数以亿计的今天，这些技术已经无法满足现代工艺的需要，人们急需一种新的工艺方法来代替传统的氟化硅玻璃等传统材料。IBM率先提出了针对0.13微米工艺的解决方案，也就是Low-K技术。

A novel partial silicon on insulator high voltage LDMOS with low-k dielectric buried layer

A novel partial silicon-on-insulator （PSOI） high voltage device with a low-k （relative permittivity） dielectric buried layer （LK PSOI） and its breakdown mechanism are presented and investigated by MEDICI. At a low k value the electric field strength in the dielectric buried layer （EI） is enhanced and a Si window makes the substrate share the vertical drop, resulting in a high vertical breakdown voltage; in the lateral direction, a high electric field peak is introduced at the Si window, which modulates the electric field distribution in the SOI layer; consequently, a high breakdown voltage （BV） is obtained. The values of EI and BV of LK PSOI with ki = 2 on a 2μm thick SOI layer over 1μm thick buried layer are enhanced by 74% and 19%, respectively, compared with those of the conventional PSOI. Furthermore, the Si window also alleviates the self-heating effect.

A Facile Strategy for Non-fluorinated Intrinsic Low-k and Low-loss Dielectric Polymers: Valid Exploitation of Secondary Relaxation Behaviors

High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming FifthGeneration Mobile Communications Technology(5 G Technology).Herein,a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains.A new amorphous non-fluorinated polymer(TmBPPA)with a k value of 2.23 and a loss tangent lower than 3.94×10^-3 at 104 Hz has been designed and synthesized,which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature.Meanwhile,TmBPPA exhibits excellent overall properties,such as excellent thermostability,good mechanical properties,low moisture absorption,and high bonding strength.As high-performance flexible circuit materials,all these characteristics are highly expected to meet the present and future demands for high density,high speed,and high frequency electronic circuit used in 5 G wireless networks.

Young's modulus determination of low-k porous films by wide-band DCC/LD LSAW

Low-k interconnection is one of the key concepts in the development of high-speed ultra-large-scale integrated（ULSI） circuits.To determine the Young＇s modulus of ultra thin,low hardness and fragile low-k porous films more accurately,a wideband differential confocal configured laser detected and laser-generated surface acoustic wave（DCC/LD LSAW） detection system is developed.Based on the light deflection sensitivity detection principle, with a novel differential confocal configuration,this DCC/LD LSAW system extends the traditional laser generated surface acoustic wave（LSAW） detection system＇s working frequency band,making the detected SAW signals less affected by the hard substrate and providing more information about the thin porous low-k film under test.Thus it has the ability to obtain more accurate measurement results.Its detecting principle is explained and a sample of porous silica film on Si（100） is tested.A procedure of fitting an experimental SAW dispersion curve with theoretical dispersion curves was carried out in the high frequency band newly achieved by the DCC/LD LSAW system.A comparison of the measurement results of the DCC/LD LSAW with those from the traditional LSAW shows that this newly developed DCC/LD LSAW can dramatically improve the Young＇s modulus measuring accuracy of such porous low-k films.

Analysis of OFF-state and ON-state performance in a silicon-on-insulator power MOSFET with a low-k dielectric trench

A novel silicon-on-insulator（SOI） MOSFET with a variable low-k dielectric trench（LDT MOSFET） is proposed and its performance and characteristics are investigated.The trench in the drift region between drain and source is filled with low-k dielectric to extend the effective drift region.At OFF state,the low-k dielectric trench（LDT） can sustain high voltage and enhance the dielectric field due to the accumulation of ionized charges. At the same time,the vertical dielectric field in the buried oxide can also be enhanced by these ionized charges. Additionally,ON-state analysis of LDT MOSFET demonstrates excellent forward characteristics,such as low gateto -drain charge density（〈 0.6 nC/mm^2） and a robust safe operating area（0-84 V）.

Mn/TiO_(2)低温SCR催化剂钾中毒机理研究

Mn/TiO_(2)具有良好的低温NH3选择性催化还原NOx(SCR)的活性。烟气中存在的碱金属会从物理和化学上毒害催化剂导致Mn/TiO_(2)催化剂中毒失活。论文以暴露{101}面TiO_(2)为载体制备Mn/TiO_(2)催化剂,采用浸渍法制备K中毒催化剂,研究了Mn/TiO_(2)低温SCR催化剂钾中毒机理。实验发现,Mn/TiO_(2)催化剂脱硝效率随K中毒浓度增加而减少;新鲜Mn/TiO_(2)催化剂表面NH3-SCR反应由E-R和L-H机理共同控制;K吸附会导致催化剂比表面积降低,催化剂表面Mn4+、化学吸附氧比例降低,表面酸性位点数量减少,导致脱硝活性降低;同时K更易吸附在Mn顶位以及桥接O位附近,导致NO的吸附活化受到严重遏制,同时削弱NH3的吸附,使得L-H机理受到阻断,只能以E-R机理控制为主。