溅射深度剖析的定量分析及其应用

本文对溅射深度剖析定量分析中广泛应用的MRI模型及其应用作了一个综述.MRI模型考虑了在深度剖析实验中,引起真实元素成分深度分布失真的三个主要因素:溅射导致的原子间混合(M),样品表面/界面的粗糙度(R),测量技术的信息深度(Ⅰ).通过考虑在溅射过程中发生的择优溅射效应,这一模型得以进一步完善.利用这一模型,可以定量分析深度剖析实验的深度分辨率,以及定量确定纳米薄膜中的互扩散系数.     

择优溅射对深度剖析谱和深度分辨率的影响

择优溅射是深度剖析实验中导致所测量元素的成分分布偏离实际的一个重要因素.本文首先在广泛应用于溅射深度剖析定量分析的MRI模型基础上,引入了一个描述择优溅射效应的参数,推导出了这个参数对所测量的深度剖面引起改变的一个解析式,并定量地模拟了择优溅射效应在深度剖析中对深度剖面形状和深度分辨率的影响.最后,应用拓展的MRI模型,定量分析了Ar+和N2+溅射Ni/Cr多层膜所得到的AES深度剖析数据,比较了相应的择优溅射比率和深度分辨率.     

三种溅射深度剖析定量分析模型解析表达式的比较

本文系统地讨论了三种广泛应用于溅射深度剖析定量分析的原子混合-粗糙度-信息深度（MRI）模型、上下坡（UDS）模型与粗糙度-级联混合-反冲注入（RMR）模型的解析表达式。先从定义、公式推导、仿真结果分析三方面逐一分析了这三种模型对应的剖面特征,再通过其对应的深度分辨率子函数、深度分辨率函数、分析膜层厚度的解析表达式以及实验数据的拟合,将三种模型进行了细致的比较。最后解释了上下坡模型存在的不足,纠正了粗糙度-级联混合-反冲注入模型存在的错误描述,实测/模拟深度剖面的动态特性验证了原子混合-粗糙度-信息深度模型的可靠性和优越性。     

硅中硼的SIMS定量分析

硅中硼的定量分析是二次离子质谱学中的一个典型基础研究课题。９０年代中，国际标准化组织选定它作为ＳＩＭＳ领域要建立的第一项国际标准。参照近十余年来清华大学与国内外有关实验室合作开展的ＳＩＭＳ定量研究情况，本文介绍并评述了硅中硼ＳＩＭＳ定量分析的进展，讨论了相对灵敏度因子法、硅中硼参考物质、影响定量分析的因素、巡回测试结果及参考物质在标定ＳＩＭＳ仪器检测限的应用。在第一次国际标准化组织巡回测试中，世界     

GaAs/GaAlAs光阴极的XPS深度剖析

GaAs光阴极是一种高性能光阴极,它由GaAs/GaAlAs外延片和玻璃基底粘接而成.为了了解外延片的元素深度分布和各层的均匀性,利用X射线光电子能谱和Ar离子刻蚀来进行深度剖析.结果表明,由于送样过程中曾短暂暴露大气,因而GaAs光阴极表面吸附有少量C、O污染,并且GaAs表层被氧化;GaAs层中的Ga、As元素含量非常均匀,约为3∶2,富Ga;而G aAlAs层中的Ga、Al和As含量比约为1∶1∶2,Ga略少于Al,但稍大于Ga0.42Al0.58As的比例.Ar离子枪采用3kV、1μA模式,刻蚀面积1 mm×1 mm,结合C-V测试得到的各层厚度数据,可以计算出该模式下各层的刻蚀速率,GaAs层的刻蚀速率约为1.091 nm/s,而GaAlAs层约为0.790 nm/s,并且推算出GaAs的溅射产额为4.00,GaAlAs的溅射产额为2.90.     

XPS结合氩离子溅射剖析Si/C多层膜的化学状态

采用X射线光电子能谱结合氩离子溅射对用作锂离子电池负极的Si/C多层膜进行了表面测试及深度剖析,获得了Si/C多层膜结构中不同深度位置的成分及化学状态.分析结果表明,Si/C多层膜中各层Si、C薄膜之间存在界面元素相互扩散,扩散至相邻层薄膜中的Si、C元素主要以化合物SiC形式存在,且处于不同位置的SiC的化学键能受周...     

高分辨率钼/硅纳米多层膜TOF-SIMS和Pulsed-RF-GDOES深度谱的定量分析

飞行时间二次离子质谱（TOF-SIMS）和脉冲射频辉光放电发射光谱（Pulsed-RF-GDOES）是两种重要的深度剖析技术,前者广泛应用于半导体工业的质量控制,后者主要应用于工业涂层及表面氧（氮）化层的分析。Mo/Si纳米多层膜由于其出色的反射特性被广泛应用于纳米光刻、极紫外显微镜等领域。本文利用原子混合-粗糙度-信息深度（MRI）模型分辨率函数,通过卷积及反卷积方法分别对Mo(3.5nm)/Si(3.5nm)多层膜的TOF-SIMS和Pulsed-RF-GDOES深度谱数据进行了定量分析,获得了相应的膜层结构、膜层间界面粗糙度及深度分辨率等信息。结果表明：GDOES深度剖析产生了较大的溅射诱导粗糙度,SIMS的深度分辨率优于GDOES。     

The influence of primary oxygen ions on SIMS depth profiling in materials implanted with cesium

The influence of implantation of oxygen as primary ions and cesium on SIMS in-depth profiles in an oxide glass was examined. For comparison samples of silicon and diamond film were used. Various behaviours of particular profiles were generally explained in terms of the chemical affinity of analysed reactants and an electric field created by implanted ions.     

SIMS depth profiling of implanted helium in Al-Mn alloy using CsHe+ molecular ion detection

The use of Cs⁺ primary ions in conjunction with the detection of CsHe⁺ molecular ions is proposed for the analysis of helium in metals by secondary ion mass spectrometry (SIMS). Concentration depth profiles of helium implanted at 100keV in Al₆₀Mn₄₀ alloy have been measured. Helium concentrations down to about 100 ppm were measured at moderately low sputtering rate of 0·5nm/sec. The experimentally determined implantation profile of helium is compared with the theoretical profile obtained using the Monte Carlo Code TRIM.     

二次离子质谱的深度分辨本领

深度剖析是二次离子质谱在半导体以及各种其它薄膜材料分析中最重要的应用，深度分辨本领是表征其分析能力的重要参数，国际标准化组织（ＩＳＯ）最近 在研究和制定这方面的国际标准。本文在概述了ＳＬＭＳ深度分辨本领影响因素的基础上，推导了δ掺杂层深度分辨函数的解析表达式，讨论了其物理意义，特别是分辨参数的定义。在ＣＡＭＥＣＡ ＩＭＳ ４ｆ仪器上用５．５ｋｅＶ的氧束对Ｓｉ中ＧａＡｓδ掺杂多层膜样品进行了深度剖析，讨论了所得分辨参数及影响因素。结合国外实验室ＩＳＯ巡回测试的结果，对深度分辨参数的定义和评估方法进行了简要评述。     

SIMS studies of low-K materials

We report progress in conducting quantitative SIMS analyses of low-K materials. Electron-beam (e-beam) pre-irradiation of SIMS measurement sites was used to study the e-beam-induced effects on SIMS depth profiling of a porous organosilicate low-K material. Pre-irradiation of the sample surface using the e-beam causes a reduction in the thickness of the low-K film. SIMS profiling was used to sputter to identifiable marker positions within the pre-irradiated film. Physical measurement of the thickness of the remaining film was used to show that the e-beam-induced reduction in thickness occurs uniformly throughout the pre-irradiated film. Exposure of the film to the e-beam prior to SIMS analysis also resulted in minor changes in the composition of the film. However, pre-irradiation of the film is not part of the normal SIMS measurement procedure. We conclude that when the e-beam irradiation is used only for charge compensation during SIMS depth profiling, the SIMS analysis of the low-K material will not be significantly affected.     

Determination of relative sputtering yield of Cr/Si

To understand the various effects induced by the ion bombardment one needs to know the sputtering yields for the sputtering conditions applied. Experimental data are rare however, and the reliability of the calculated values should be checked. Thus the measurement of sputtering yield is important. Recently, we have published a work where we have applied AES depth profiling to determine the relative sputtering yield [Barna A, Menyhard M, Kotis L, Kovacs GyJ, Radnoczi G, Zalar A, et al. J Appl Phys 2005; 98:024901-6]. In this communication, we will describe the method in a more detailed way discussing the reliability as well. It will be applied for Si/Cr multilayer structure (similar to those used in devices of integrated electronics) consisting three Si and three Cr layers sputter deposited onto smooth silicon substrates. The ion energy and projectile were 1 keV and Ar⁺, respectively. The angle of incidence varied in the range 22°-87°. The reliability of the derived relative sputtering yields will be discussed and will be compared with those provided by the available simulation.     

SIMS and GDMS depth profile analysis of hard coatings

Rapid development in hard coating technology calls for simple construction depth profile analysers. Here we present results of depth profile analysis of a set of Ar arc plasma deposited TiN, CrN layers. The results are obtained with the use of recently constructed simple glow discharge mass spectrometer (GDMS) and compared with secondary ion mass spectrometer (SIMS). In SIMS (SAJW-05 model) we apply 5 keV Ar⁺ ion beam of about 100 μm in diameter. Digitally controlled spiral scanning of primary ion beam is performed over 1.6 mm² area. Secondary ions are extracted from the central part due to an “electronic gate” and analysed by quadrupole mass spectrometer QMA-410 Balzers (16 mm rods).GDMS analyses are performed on SMWJ-01 glow discharge prototype spectrometer. To supply discharge in 1 hPa argon we use 1.5 kV DC voltage. The analysed sample works as a cathode in a discharge cell. Area of the analysis is ∼4 mm² due to the use of secondary cathode—high purity tantalum diaphragm. Sputtered atoms are ionised, next extracted into the analytical chamber and finally analysed by the quadrupole mass analyser SRS-200 (6 mm rods).The results show that the use of simple construction GDMS analyser allows obtaining similar or even slightly better depth resolution than it can be obtained in the SIMS spectrometer. Application of glow discharge analysis opens new possibilities in direct quantitative depth profile analysis of hard coatings.     

Compositional depth profile investigation of plasma nitriding by multiple analyses techniques

Compositional depth profile in plasma nitriding is investigated by several experimental techniques including EDS, GDOES and SIMS as well as a calculated method. Plasma nitriding was carried out on high purity iron substrate at a temperature of 550 °C in an atmosphere of 75 vol.% H₂-25 vol.% N₂ for time periods of 1, 2, 5 and 10 h. SEM and XRD methods were used for microstructural evaluation and phase identification. According to EDS, GDOES and calculated data, composition of the compound layer reached nearly to Fe-8 wt% N and Fe-6 wt% N indicating ε-Fe_2-3N and γ′-Fe₄N nitrides were formed, respectively. Although nitrogen concentration was decreased to nearly zero close to the nitrided surface, calculated data and SIMS profiles show very smooth gradient in diffusion zone down to several hundreds of micrometers. The results of compositional depth profiling by EDS, GDOES and SIMS indicated good agreement between experimental findings and, thus, the techniques completed one another. It was found that EDS and GDOES are appropriate for analysis of Fe and N in the compound layer, but both have limitations for profiling of nitrogen in the diffusion zone. SIMS, on the other hand, was distinguished as a professional technique for accurate measurement of nitrogen within the diffusion zone. The experimental depth profiles indicated good consistency with calculated diffusion profiles for all treatment cycles.     

Evaluation of the depth resolutions of Auger electron spectroscopic, X-ray photoelectron spectroscopic and time-of-flight secondary-ion mass spectrometric sputter depth profiling techniques

Concentration-depth profiles of sputter-deposited Si/Al multilayered specimens were determined by model fitting to measured data obtained by depth profiling, using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). The model used for calculation of the concentration-depth profile accounts for the broadening (“smearing”) upon experimental depth profiling owing to the effects of atomic mixing, preferential sputtering, surface roughness and information depth of either the Auger electrons (for AES depth profiling) or the photoelectrons (for XPS depth profiling) or the secondary ions (for SIMS depth profiling). The depth resolution for each technique was derived directly from the values determined for the fitting parameters in the model.     

Accurate measurement and evaluation of the nitrogen depth profile in plasma nitrided iron

Nitrogen depth profile of plasma nitrided pure iron was measured and evaluated by accurate experimental techniques. Plasma nitriding cycles were carried out on high purity iron substrate in an atmosphere of 75% H₂-25% N₂. Nitrogen concentration depth profiles in the compound layer and the diffusion zone were characterized by glow discharge optical emission spectroscopy (GDOES) and secondary ion mass spectroscopy (SIMS), respectively. Nitrogen diffusion depths were measured accurately by optical and scanning electron microscopy as well as SIMS technique at different nitriding times. Experimental results indicated good agreement between SIMS data and microscopic evaluations for various nitriding cycles. The results of SIMS showed the nitrogen diffusion depth of about 2000 μm in the diffusion zone for 10 h plasma nitriding at 550 °C. Such high depth had not been detected in previous investigations in which the conventional methods such as EDS, GDS, XPS, EPMA or ion probe techniques were used.