测控技术与仪器外文翻译@中英文翻译@外文文献翻译

中北大学 2005 届本科毕业设计说明书 第 1 页共 13 页 过滤阴极真空电弧镀膜技术所制得氧化铝薄膜的结构和特性 摘要 ： 通过过滤阴极真空电弧镀膜技术制备氧化铝薄膜时，其内部结构、组成、形态、光学和机械性能被详尽的描述，这些都与制备时氧气的流量有关。薄膜结构、组成、形态和性能都是很重要的，随着氧气流量的 增加，薄膜的结构也由非晶体经过一系列变化到单晶体，随着 O/Zr原子比率的增加和 Z 离子由低氧化作用的状态转化为 Zr4+ 再一次形成非晶体。形成这样的结构是由于其内部结构的变化而引起的，并且影响其形态和机械性能，以致这种非晶体薄膜表面有一些小簇，其光滑程度就像低硬度的多 晶体薄膜。当反射指数和系数相对接近最大值时，在发射率和光学带宽随着O/Zr 比增加时，薄膜的组成来决其光学性能而非其密度。 1.说明 在大气压力下由于三种不同温度有多种不同靶形态结构，单晶体时低于 1170OC，四面体时为 1170-2370OC， 2370OC 为立方体，知道 2680OC 时形成金属。 Zr 有很高的反射指数，大光学带宽间距，和很低的光损失及在 0.3-8范围内高透明度 ,所以被广泛的应用于光学领域。 此外， Zr 具有很高的电介质，低泄露量等特点，最有可能代替做电解质的晶体管。进而，由于 Zr 很低的传热性，它成为 了装置中隔热层的首选。 Z其他的特性如：高硬度、高抗氧性也使其成为机械材料中的热门。至今为止，已经有很多制备 Z 的方法，例如反应磁控溅射，离子辅助反应溅射，化学气相沉积等。薄膜特性的优劣取决于制备过程及其参数。 过滤阴极真空电子弧镀膜技术，在低电压和高电流状态下工作。通过磁性机械过滤器来防止微粒从阴极发射。它提供了一种具有很高能量的沉积离子源，远大于相应的热蒸发和磁控溅射。能有效去处宏观无用微粒，很明显能提高薄膜质量并拓展其应用。固有的高能量提高薄膜的附着性和密度。由于能力是离子辅助沉积中最重要的参数，这种 制备的方法已经有了一些应用，已经应用于在高热平衡和高 SP3 状态下碳薄膜的制备，还合成了一些金属氧化物的薄膜。然而对我们最有利的是，很少有关过滤阴极真空电子弧镀膜技术制备 ZrO2薄膜的知识。 我们现在的工作是系统研究在不同 O2流量与 ZrO2 薄膜的结构、组成、表面形态和性质之间的关系。我们的结论表明薄膜的结构、组成特性都与 O2流量有关系。 过滤阴极真空电子弧镀膜技术所制的薄膜特性与其他方法相比，更说明了该方法的优中北大学 2005 届本科毕业设计说明书 第 2 页共 13 页 越性。 2.实验 图 1 为制备设备。该图已经详细反应了这个系统，各个部分都表现了出来。该系统 有一个双倍滤光器，可以使弧自身发射出微粒。阴极 Zr 原子在 120A 电流下，阴、阳极瞬间接触点燃喷出的浆体，该浆体是从一个 400mT 的磁场放射出来并压缩的。一个旋转泵和一个冷凝泵可使这个系统的压力达到 4 10-6T。 O2通过一个有很多小孔的铜管进入 Zr 靶附近区域。这种发射 O2 的方式可使 O2电离到最大程度，因此增加了与浆体的接触使得 Zr 与 O2之间发生充分的反应。 O2流量可选择 10-98sccm,在制备过程中，随着 O2流量的增加，靶的氧化更加充分。 O2 增加使得靶材充分氧化，并且损失了冷凝粒子，使得制备的速率 75nm/s 降至 35nm/s。 在室温下薄膜生长在 n-si 和石英表面。基片被放在制备室之中，按顺序被丙酮、酒精和未电离的水清洗。所制得的薄膜厚度大约在 200 nm。 通过由 CUK做源的 XRD 法可得出薄膜所处阶段和晶体结构。光谱计记录下反射率等参数，光学特性也被软件检测。主要特征和组成分析被 XPS 通过 ALK 辐射测得到。不可使用没有清洗过的样品溅射，以免所溅射得到的薄膜化学组成发生变化。 图 1 3.结果 3.1 结构 中北大学 2005 届本科毕业设计说明书 第 3 页共 13 页 图 2 表明在不同 O2流量 ZrO2薄膜由 XRD 测得的结构，在 10sccm时，在曲线中对应着边缘处，而系统峰值在 32.4oC附近，为标准的结构。这个高峰来自于没有完全氧化的 ZrO 固体。由于类似现象可看出峰值点又是不对称的和急剧变化处。当 O2流量增加至 20sccm，一个最高峰是当晶体阶段，相对弱的高峰是多晶体阶段。氧气流量决定峰值。我们可以检测出它是怎么影响薄膜结构的。在 35sccm 时，出现了更多的弱高峰，在 m(200)处峰值变得很弱，在 m（ -202m）变得很强。然而当氧气的流量增加至 65sccm时，薄膜由多晶体变为无定形，在弯曲处出现更宽的高峰。结构的不同反应出 02流量在薄膜 结构形成中扮演了很重要的角色。正在一 定流量范围内（ 20-50sccm）薄膜保持在多晶体状态，而在纯单晶体阶段在不同的 范围内。 3.2 化学组成和化学状态 通过典型的 XPS 光谱测量可以得到由光电离子及 Zr 和 O 转变达到高峰，在与空气接触后的抽样中经过观察 C1S 是主要表面组成部分。在 Zr3d 和 O1S 处出现两个高峰。图 4中可看到常态的元素和由 XPS 测得的局部光谱。频谱非常接近标准单晶体的 ZrO2。两个高峰， Zr3d5/2和 Zr3d3/2时的能量分别为 181.8ev 和 184.2ev，非常接近在中标准ZrO2， 并且是对称的，在氧化状态的薄膜中只有它。他们的强度比率和导致旋转轨道在1.5ev 和 2.4ev 的能量间隔和其他研究是一致的。一个不对称的高峰能分解为的529.6evLBE 能量和 531ev 的 HBE，与报告中的那些类似。 相比之下，薄膜沉积速率很低时，例如 35sccm， Zr3d 光谱是以某种方式不同的而 O1S中北大学 2005 届本科毕业设计说明书 第 4 页共 13 页 频率是十分类似的。出现较低能量接近其边缘，有形式为 Zr,Zrn+,(n=1,2,3)氧化物存在。可得出随着 O2流量的不同可转变为使得和发生充分的反应。氧化程度的不同也被表明，薄膜中 O和 Zr 的原子比率可由它们在峰 值区域的灵敏度算出。 O1S 的 HBE 是一个小片段所以高峰不能被确定。正如预料， O/Zr 比增加可导致更多氧化。可看到在薄膜沉积速率为时， O/Zr 比为 1.98： 1 接近原子比为 2： 1，在 65sccm 及起以上，薄膜 3.3 表面形态 五表现了在 65sccm 时典型的薄膜。在薄膜表面，小簇由相同的冷凝的原子成。 这表面相当干净和光滑， RMS 粗燥率小于 0.1nm 在 1um 1um 区域内。上面提到的高能量轰击微粒使得形成干净、光滑的表面 ，这些微粒运动时损失粒子，或者促进原子和提供足够能量运动到生长表面相结合，再一次建议 流 量的边界值不影响原子的运动，与 XRD 测量结果一致。 有趣的是，薄膜的形态似乎也被 O2流动速率 XRD 分析出的薄膜结构的改变有关。在 10sccm 时，薄膜表面的簇会很大。这种簇的变化可以反映出薄膜表面粗糙。 XRD 分析出的薄膜结构的改变说明薄膜表面结构与 O2的流量有关。 换句话说，与无定型薄膜相比较，这种多晶体薄膜在 20-50sccm 速率下在表面形成巨大的簇并且看起来很粗糙。 中北大学 2005 届本科毕业设计说明书 第 5 页共 13 页 3.4 机械性能 薄膜的硬度是测量抵制塑性变形和确定载荷符合凹行区域的峰值。实际上，硬度通过卸载数据所构成能量方程来表现。薄膜的 机械性能作为流量方程显示在图 9，其值平均至少出现了 3次，微硬度和是依赖于氧气流量。当流量由 10sccm 增加到 20sccm，硬度几乎维持为 13.6GP,再增加流量会导致硬度急速提高。在 35。 50，硬度仍然在增加，超出 50sccm 后，薄膜开始变软，并且在 65sccm 会降至 13.4GPA。显然，硬度的改变非常接近在 XRD 式样中观察的。这表明硬度是由薄膜 的结构确定而非特性确定其硬度，这与 KAO 的报告结果不一致。 中北大学 2005 届本科毕业设计说明书 第 6 页共 13 页 4.结论 通过过滤阴极真空电弧镀膜技术制备薄膜，研究了在不同氧气流量时，薄膜的结构、组成、 形态、光学性能和机械性能，最终的流量达到了 98sccm。经研究发现 O2的流量是薄膜结构、组成、特性的重要参数。随着 O2 流量的增加，薄膜的结构由无定型到不同氧化率的单晶体再到无定型；随着 0/Zr 原子比的增加， Zr 原子由低氧化率到 Zr。这种与氧气流量有关的结构趋势会导致薄膜组成的改变并且决定表面形态和薄膜的机械性能。 中北大学 2005 届本科毕业设计说明书 第 7 页共 13 页 g.q. yu b.k. tay_ z.w. zhao Structure and properties of zirconium oxide thin films prepared by filtered cathodic vacuum arc School of Electrical and Electronic Engineering, Nanyang Technological University,Singapore, 639798, Singapo Received: 19 September 2003/Accepted: 17 January 2004 Published online: 1 April 2004 Springer-Verlag 2004 ABSTRACT Zirconium oxide (ZrO2) thin films deposited atroom temperature by the filtered cathodic vacuum arc (FCVA) technique are detailed in terms of the film structure, composition, morphology, and optical and mechanical properties, which are tailored by the oxygen (O2) flow rate during deposition. The relationships between the film structure, composition, morphology, and properties are emphasized. With an increasing flow rate, the film evolves in structure from amorphous, through a pure monoclinic phase with varying preferential orientation, to amorphous again, accompanied by an increase in the O/Zr atomic ratio and a conversion of Zr ions from low oxidation states into Zr4+. Such a structural trend arises from the change in composition, and influences the film morphology and mechanical properties so that the amorphous films exhibit small clusters on the surface and smoother morphology as well as lower hardness compared with the polycrystalline films. The film composition rather than the density dominates the optical properties, where the transmittance and the optical band gap increase with increasing O/Zr values, while the refractive index and extinction coefficients behave conversely with the lowest refractive index (2.16 at 550 nm) approaching the bulk value (2.2). PACS 68.55.Jk； 78.66.Nk； 68.37.Ps 1. Introduction Zirconium oxide (ZrO2) has three temperature dependent polymorphic structures at atmospheric pressure. A monoclinic phase is stable at temperature below 1170 C, a tetragonal between 1170 and 2370 C, and a cubic from 2370 C to the melting point at 2680 C. ZrO2 is widely used in optical fields 13, because of its high refractive index,large optical band gap, and low optical loss and high transparency in the 0.38 m range. In addition, ZrO2 is a promising candidate to replace silicon dioxide as the gate dielectric in transistors, due to its high dielectric constant ( 25), lowleakage current level, etc. 46. Furthermore, ZrO2 has potential as a thermal barrier coating in devices due to its low thermal conductivity 7, 8. Other properties such as high hardness, large resistance against oxidation, also make it interesting as a mechanical material 9. To date, many efforts to prepare ZrO2 have been made by various deposition techniques, for example, reactive magnetron sputtering 1013, ion-assisted reactive sputtering or evaporation deposition 8, 1425, solgelmethods 26, chemical vapor deposition 4, 中北大学 2005 届本科毕业设计说明书 第 8 页共 13 页 17, and so on. The film properties are generally strongly dependent on the deposition process and parameters. The filtered cathodic vacuum arc technique (FCVA) 2729, operated at low pressure, low voltage, and high current, effectively eliminates micro-sized (0.110 m) macroparticles from being emitting from cathode materials during arcing by means of mechanical, magnetic, or electrical filters, or a combination of these. It also provides an intense source of fully ionized deposition specieswith energies (50150 eV) greater than counterparts produced in thermal evaporation or magnetron sputtering 30, 31. The removal of detrimental macro-particles undoubtedly improves the resulting film quality and extends the application of the deposition technique. The inherent high-energy could increase the film adhesion and the packing density. The full ionization of the deposition species allows tailoring of the film properties with substrate bias, since kinetic energy is one of the most important parameters as in ion beam assisted deposition (IBAD) 8. This technique has been demonstrated in the preparation of a diamond-like carbon film with high thermal stability and a high sp3 32, to fill trenches 33, 34, as well as the synthesisof certain metal oxide films 35, 36. However, to the best of our knowledge, little work has been reported on ZrO2 synthesis by the (FCVA) technique.In the present work, we systematically investigate the structural, chemical composition, optical, and mechanical properties of ZrO2 films deposited at different oxygen (O2) flow rates by FCVA. The emphasis is placed on the relationships between structure, composition, surface morphology, and properties of the films. Our results disclose that the structural and compositional properties of the films are considerably influenced by the O2 flow rate. The variation in composition induces structural transformation from amorphous through a pure monoclinic phase to amorphous again, and determines the optical properties,whereas the change in structure controls the mechanical properties and affects the surface morphology. The properties of the films are also crosscompared with those of films prepared by other methods to highlight the FCVA features. 2 Experimental A schematic diagram of the FCVA deposition system is shown in Fig. 1. The details regarding the main principles of the system have been described elsewhere 37. Briefly, the system incorporates an off-plane double bendfilter, which effectively removesmacro-particles originating from the arc itself. A Zr cathode (99.98% pure) operated at 120 A dc current is ignited through instant contact between cathode and anode to obtain the plasma, which is steered out by a toroidal magnetic field fixed at 40 mT to condense on a substrate. The base pressure of the system, evacuated by a rotary pump and a cryo-pump, can reach 4 106 Torr. O2 gas (99.99% pure) is led into the region near the Zr target through a copper tube on which many tiny holes are distributed. This way of introducing O2 is expected to maximize O2 ionization due to its relatively increased collision with the plasma, possibly promoting a chemical reaction between O2 and Zr. The O2 flow rate chosen here is varied from 10 to 98 sccm corresponding to 1 104 to 4.6 104 Torr. During deposition, the deposition rate decreases from 75 to 35 nm/min with an increasing O2 flow rate as a result of increased .oxidization of the target, and collision-induced loss of condensing particles. The films are grown on n-Si (100) and quartz substrates at room temperature. 中北大学 2005 届本科毕业设计说明书 第 9 页共 13 页 All the substratesare sequentially cleaned in acetone, alcohol, and de-ionizedwater prior to being loaded into the deposition chamber. All the films being investigated are generally around 200 nm thick. The film phase and crystal structure are identified by Xray diffraction (XRD) with a Cu K source at 1.54 . Transmittance and reflectance are recorded from 200 to 1100 nm with a spectrometer. Optical constants are obtained by fitting optical spectra with Scout software 38. Core level spectra and compositional analysis are and compositional analysis are carried out by X-ray photoelectron spectroscopy (XPS) with monochromatic Al K radiation (1486.6 eV). No sputter cleaning of the samples is performed to avoid changes in chemical compositions induced by preferential sputtering. The spectrum obtained is corrected by an adventitious C1s peak at 284.6 eV. Surface morphology is measured by atomic force microscopy (AFM) in tapping mode (Dimension 3000 scanning probe microscope from Digital Instruments). The mechanical properties on a nano-scale are obtained by a nanoindentation technique apparatus (Hysitron Inc.) attached to the above AFM equipment. Nanoindentations were made using a Berkovich diamond indenter and the maximum loads applied were 500 N. The indenter was loaded at 100 N/s, held at peak load for 5 s and then finally unloaded at 100 N/s. 3 Results 3.1 Structure Figure 2 shows theXRDpatterns for ZrO2 films deposited at differentO2 flowrates.At 10 sccm, a broad but symmetric peak centered at around 32.4 is observed in curve (a), indicative of an amorphous structure. The peak is believed to come from an oxygen-deficient Zr-O solid 中北大学 2005 届本科毕业设计说明书 第 10 页共 13页 solution 40. Wong et al. 13 also reported a similar phenomenon, where, however, the peak was unsymmetric and sharp. As the O2 flow rate increases to 20 sccm (Fig. 2b) ), one peak at 33.7 assigned to (200) planes of monoclinic phase (denoted as m(200) is predominant, accompanied by the appearance of other weak peaks also from the monoclinic phase. This rapid occurring of diffraction peaks shows that so much oxygen is incorporated that sufficient ZrO2 crystallite forms which can be detected. The easy combination between Zr and O is possibly related to charged and therefore active emitted species, as well as further stimulated by energetic Zr particles bombarding the surface as in IBAD. At 35 sccm, in addition to more weak peaks, them(200) peak becomes weaker while the m(-202) peak gets stronger. When the O2 flow rate goes up to 50 sccm, the dominant peak is changed to m(-111) while many more monoclinic peaks are produced. 3.2 Chemical compositions and chemical states It was concluded from a typical XPS survey spectrum (not shown) that besides the peaks contributed by photoelectrons and Auger transitions of Zr and O, C1s is observed as well, which is mainly from surface contamination after exposure of the sample to air. The two strong peaks at 185.9 and 533.2 eV are identified as Zr 3d and O1s, respectively. Fig. 4 presents the normalized Zr 3d (a) and O1s (b) XPS local spectra for the film prepared at 50 sccm. The spectra closely resemble those observed in standard monoclinic ZrO2 42. Two peaks, Zr 3d5/2 and Zr 3d3/2 observed at binding energies of 181.8 and 184.2 eV, very near to the values of Zr4+ in ZrO2 42, are symmetrical, denoting that only one oxidation state of Zr exists in the film. Their intensity ratio (I3d5/2/I3d3/2) and energy interval (3d5/23d3/2) resulting from spin-orbit splitting are 1.5 and 2.4 eV, in agreement with other studies 20, 42. An asymmetric O1s peak can be decomposed into two components peaked at a low binding energy (LBE) of 529.6 eV and high binding energy (HBE) of 531.6 eV, quite comparable with reported ones 14, 43. It has been accepted that the LBE peak is assigned to the oxygen in zirconia 14, 20, 43 while the HBE is attributed to oxygen present in the hydroxide and/or 中北大学 2005 届本科毕业设计说明书 第 11 页共 13页 adsorbed oxygen or carbonates or higher-valent oxides 14, 42, 44, 45.Matsuoka et al. 20 ascribed it to oxygen possibly bound to Zr. In contrast, for the film deposited at the low flow rate, i.e., 35 sccm, the Zr 3d spectrum is somehow different whereas the O1s spectrum is very similar. A shoulder of the Zr 3d5/2 clearly appears at the lower binding energy side (Fig. 4c), indicating that other oxidation states of Zr (Zrn+, n = 1, 2, 3) occur. This shoulder is attributed to Zr suboxides 14, 20. It can be concluded from this discrepancy that with increasing flow rate, Zrn+ (n 3) will convert into Zr4+ due to a full reaction between Oand Zr in the films. This consistent variation in the oxidation state of Zr ions with the film composition was also reported in 20. The atomic ratio of Oto Zr (O/Zr) in the films can be calculated with their respective peak areas cali- brated by their sensitivity factors (0.66, 2.1, 0.66 for O1s and Zr 3d). For the calculation, theO1s HBE peak is not included due to its small fraction. As expected, theO/Zr ratio increases with more addition of oxygen (not shown). Note that for the film deposited at 50 sccm, the O/Zr ratio obtained is approximately 1.98 : 1, near to the ideal stoichiometric ratio of 2 : 1. At 65 sccm and above, the films are over-stoichiometric ( 2.2 : 1). 3.3 Surface morphology Figure 5a presents a typical top-view AFM image of the film at 65 sccm. On the film surface, the clusters composed of many condensing adatoms are uniformly distributed. The surface is quite clear and smooth, with its rootmean-square (RMS) roughness less than 0.1 nmover the area of 1 m 1 m. This clearness and smoothness is associated with the above-mentioned high energy of bombarding particles, which possibly removes loose particles (so-called “self-sputtering”) or promotes bonding between adatoms and offers the adatoms enough lateral mobility on the growing surface 39, 46, again suggesting that the flow rate range selected does not greatly affect the adatoms mobility, in accordance with the XRD results. Interestingly, the film morphology seems to be affected by the O2 flow rate as well. At 10 sccm, the clusters distributed on the film surface are similar in size to that for the film at 65 sccm. However, in the range of 20 to 50 sccm, larger clusters are present on the surface. This change in cluster size is also reflected in the curve of roughness versus the O2 flow 中北大学 2005 届本科毕业设计说明书 第 12 页共 13页 rate (Fig. 5b) the O2 flow rate (Fig. 5b), where the roughness is larger for a 2050 sccm flow rate range. The flow rate-dependent surface morphology could be correlated with the film structural change as drawn from XRD analysis. In other words, compared with the amorphous films, the polycrystalline films formed in a 2050 sccm flowexhibit larger clusters on the surface and look relatively rougher. 3.4Mechanical properties The film hardness is a measure of resistance to plastic deformation and defined as the peak load divided by the corresponding indentation area. Practically, the hardness is obtained by fitting the unloading data with a power law equation