Deposition of AlN films by reactive sputtering: Effect of radiofrequency substrate bias

Piezoelectric AlN thin films were deposited on Silicon substrates by triode reactive sputtering. The variation of residual stress versus bias voltage on the substrate was investigated. A compressive stress was always observed with a maximum value for a negative substrate bias of 50 V. For higher negative bias voltage values, the compressive stress decreases. X-ray diffraction measurements showed two kinds of growth orientation. First, without bias voltage, films are well crystallized and (002) oriented. Second, with bias voltage, the (002) orientation disappears and a small peak appears (situated in the 2θ = 32°-33° range) which can be attributed to (100) orientation. Finally, the influence of compressive stress and ion bombardment on the change of orientation is discussed.     

Bias effect on microstructure and mechanical properties of magnetron sputtered nanocrystalline titanium carbide thin films

Nanocrystalline titanium carbide (TiC) thin films were prepared by magnetron sputtering deposition at 473 K. The effect of substrate bias on microstructure and mechanical properties was studied in details using X-ray photoelectron spectroscopy, X-ray diffraction, field emission scanning electron microscopy, indentation and scanning microscratch. The TiC films exhibit a (111) preferential orientation. Substrate bias decreases grain size and deposition rate of the TiC films. The TiC films have columnar structure which becomes finer at high substrate bias. Nanoindentation hardness, Young's modulus, and toughness of the films are increased as the substrate bias goes up. However, the adhesion peaks at substrate bias of − 100 V and drops when bias is increased further.     

Influence of substrate bias voltage on the microstructure and residual stress of CrN films deposited by medium frequency magnetron sputtering

In this study, CrN films were deposited on stainless steel and Si (1 1 1) substrates via medium frequency magnetron sputtering under a systematic variation of the substrate bias voltage. The influence of the substrate bias voltage on the structural and the mechanical properties of the films were investigated. It is observed that there are two clear regions: (1) below −300 V, and (2) above −300 V. For the former region, the (1 1 1) texture is dominated as the substrate bias voltage is increased to −200 V. The lattice parameter is smaller than that of CrN reported in the ICSD standard (4.140 Å) and the as-deposited films exhibit tensile stress. Meanwhile, the surface roughness decreases and the N concentration show a slow increase. For the latter region, the (2 0 0)-oriented structure is formed. However, the lattice parameter is larger as compared with the value reported in the ICSD standard, and the surface roughness increases and the N concentration decreases obviously. In this case, the compressive stress is obtained.     

Effect of process parameter changes on the composition of magnetron sputtered and evaporated TiN and AlN films measured by UHV in-situ techniques

TiN and AlN films are deposited on HSS steel substrates in an ultrahigh vacuum magnetron system equipped with in-situ Auger electron spectroscopy (AES) and mass spectrometric sensors for plasma diagnostics. The composition of TiN_x coatings is measured by AES as a function of the N₂ pressure, the bias voltage, and the d.c. power. The flux of ionic particles impinging on the substrate surface and their energies are determined by a quadruple mass analyzer mounted behind a hole in the substrate. In addition, the reactivity of neutral nitrogen molecules in a reactive evaporation process is measured by a quartz crystal microbalance.     

Effect of substrate bias voltage on the physical properties of dc reactive magnetron sputtered NiO thin films

Nickel oxide (NiO) thin films were prepared on glass substrates at various bias voltages using dc reactive magnetron sputtering technique. The influence of substrate bias voltage on structural, optical and electrical properties was systematically investigated using X-ray diffraction (XRD), SEM, EDS, spectrophotometer and Hall effect studies. The NiO films are crystalline with preferential growth along (2 0 0) plane. The NiO films exhibit optical transmittance of 55% and direct band gap of 3.78 eV at the substrate bias voltage of −75 V. The electrical resistivity decreases as substrate bias voltage increases from 0 to −75 V thereafter it was slightly increased.     

Morphological study of magnetron sputtered Ti thin films on silicon substrate

Titanium films on Si(1 0 0) substrate were deposited by DC-magnetron sputtering. The effect of substrate temperature on the microstructural morphologies of the films was characterized by using field emission-based scanning electron microscopy/electron back scattered difffraction (FE-SEM/EBSD) and atomic force microscopy (AFM). X-ray diffraction was used to characterize the phases and crystallite size of the Ti films and it was observed that according to the first figure of this article: (0 0 2) orientation increases from 200 °C and it changes into (1 0 1) orientation from 300 °C. The SEM analysis of the Ti films, deposited in Ar atmosphere, showed two- and three-dimensional hexagonal structure of the grains at the substrate temperature of 200 °C and >200 °C, respectively. The increase in grain size of Ti films with the substrate temperature was confirmed by EBSD and AFM characterization. The average surface roughness of the Ti films has increased with increase in substrate temperature as evident from the AFM study.     

Effects of outgassing on the reactive sputtering of piezoelectric AlN thin films

A series of study of the effects of outgassing on pulsed-DC reactive sputtering of highly (0002)-textured AlN thin film was conducted with systematically adjusted sputtering parameters like working pressure, atmosphere, and temperature. The film quality was evaluated by its rocking curve width and residual stress, both utilizing X-ray diffraction methods, as well as by SEM and XPS analyses. It is found that with lower outgassing all the above-mentioned sputtering parameters become less effective on both rocking curve width and residual stress. The rocking curve FWHM (Full Width at Half Maximum) measurements even exhibit apparently insensitive regions to the sputtering parameters, and accompanied threshold behaviors as well. XPS analysis reveals higher oxygen content while SEM observation shows thinner and slanter columnar structure in the AlN film when outgassing is higher upon sputtering.     

Deposition of c-axis orientation aluminum nitride films on flexible polymer substrates by reactive direct-current magnetron sputtering

Aluminum nitride (AlN) piezoelectric thin films with c-axis crystal orientation on polymer substrates can potentially be used for development of flexible electronics and lab-on-chip systems. In this study, we investigated the effects of deposition parameters on the crystal structure of AlN thin films on polymer substrates deposited by reactive direct-current magnetron sputtering. The results show that low sputtering pressure as well as optimized N₂/Ar flow ratio and sputtering power is beneficial for AlN (002) orientation and can produce a highly (002) oriented columnar structure on polymer substrates. High sputtering power and low N₂/Ar flow ratio increase the deposition rate. In addition, the thickness of Al underlayer also has a strong influence on the film crystallography. The optimal deposition parameters in our experiments are: deposition pressure 0.38 Pa, N₂/Ar flow ratio 2:3, sputtering power 414 W, and thickness of Al underlayer less than 100 nm.     

Effects of pulse parameters on the pulsed-DC reactive sputtering of AlN thin films

A series of studies on the pulsed-DC reactive sputtering of highly (002)-textured aluminum nitride (AlN) thin films was conducted with systematically adjusted pulse parameters including reverse voltage, pulse frequency, and pulse duration. The film quality was evaluated by the full width at half maximum (FWHM) of the (002) rocking curve as well as the (002) peak intensity. In the asymmetric bipolar mode, the FWHM increases while the peak intensity decreases with reverse voltage, implying a detrimental effect of reverse voltage on the quality of AlN film. Whereas in the unipolar mode, the film quality improves with pulse frequency as evidenced by the decreasing FWHM and increasing peak intensity. It is also found that there is a critical pulse duration of about 500 μs, beyond which the FWHM starts to increase while the peak intensity starts to decrease due to target poisoning. Typical measurements on thus-optimized AlN film show a roughness of 1.7 nm and a (002) FWHM of less than 1.9°.     

Effect of deposition angle on the structure and properties of pulsed-DC magnetron sputtered TiAlN thin films

This article reports the comparison of structure and properties of titanium aluminum nitride (TiAlN) films deposited onto Si(100) substrates under normal and oblique angle depositions using pulsed-DC magnetron sputtering. The substrate temperature was set at room temperature, 400 °C and 650 °C, and the bias was kept at 0, − 25, − 50, and − 80 V for both deposition angles. The surface and cross-section of the films were observed by scanning electron microscopy. It was found that as the deposition temperature increases, films deposited under normal incidence exhibit distinct faceted crystallites, whereas oblique angle deposited (OAD) films develop a kind of “tiles of a roof” or “stepwise structure”, with no facetted crystallites. The OAD films showed an inclined columnar structure, with columns tilting in the direction of the incident flux. As the substrate temperature was increased, the tilting of columns nearly approached the substrate normal. Both hardness and Young's modulus decreases when the flux angle was changed from α = 0° to 45° as measured by nanoindentation. This was attributed to the voids formed due to the shadowing effect. The crystallographic properties of these coatings were studied by θ-2θ scan and pole figure X-ray diffraction. Films deposited at α = 0° showed a mixed (111) and (200) out-of-plane orientation with random in-plane alignment. On the other hand, films deposited at α = 45° revealed an inclined texture with (111) orientation moving towards the incident flux direction and the (200) orientation approaching the substrate normal, showing substantial in-plane alignment.     

Influence of substrate bias voltage on properties of Pt thin films deposited by non-mass separated ion beam deposition method

Pt thin films were deposited on Si substrates by applying a negative substrate bias voltage using a non-mass separated ion beam deposition method. The effect of the substrate bias voltage on the properties of the deposited films was investigated. In the case of Pt thin films deposited without the substrate bias voltage, a columnar structure and small grains were observed. The electrical resistivity of the deposited Pt films was very high (49.3 ± 0.65 µΩ cm). By increasing the substrate bias voltage, no clear columnar structure was observed. At the substrate bias voltage of − 75 V, the resistivity of the Pt film showed a minimum value of 16.9 ± 0.2 µΩ cm closed to the value of bulk (10.6 µΩ cm).     

Influence of deposition parameters on preferred orientation of RF magnetron sputtered BST thin films

Ba_0.65Sr_0.35TiO₃ (BST) thin films have been deposited by radio frequency magnetron sputtering. The effects of the deposition parameters on the crystallization and microstructure of BST thin films were investigated by X-ray diffraction and field emission scanning electron microscopy, respectively. The crystallization behavior of these films was apparently affected by the substrate temperature, annealing temperature and sputtering pressure. The as-deposited thin films at room temperature were amorphous. However, the improved crystallization is observed for BST thin films deposited at higher temperature. As the annealing temperature increased, the dominant X-ray diffraction peaks became sharper and more intense. The dominant diffraction peaks increased with the sputtering pressures increasing as the films deposited at 0.37–1.2 Pa. With increasing the sputtering pressure up to 3.9 Pa, BST thin films had the (110) + (200) preferred orientation. Possible correlations of the crystallization with changes in the sputtering pressure were discussed. The SEM morphologies indicated the film was small grains, smooth, and the interface between the film and the substrate was sharp and clear.     

Effect of annealing on molybdenum doped indium oxide thin films RF sputtered at room temperature

Thin films of molybdenum doped indium oxide (IMO) were deposited on glass at room temperature using an in-built three-source RF magnetron sputtering. The films were studied as a function of oxygen volume percentage (O₂ vol. %; ranging from 0.0 to 17.5%) in the sputtering chamber. The as-deposited amorphous films were crystallized on post-annealing. The as-deposited films are low conducting and Hall coefficients were undetectable; whereas post-annealed films possess fairly high conductivity. The lowest transmittance (11.96% at 600 nm) observed from the films deposited without oxygen increased to a maximum of 88.01% (3.5 O₂ vol. %); whereas this transmittance was decreased with the increasing O₂ vol. % to as low as 81.04% (15.6 O₂ vol. %); a maximum of 89.80% was obtained from the films annealed at 500 °C in open air (3.5 O₂ vol. %). The optical band gap of 3.80 eV obtained from the films deposited without oxygen increased with increasing O₂ vol. % to as high as 3.91 eV (17.5 O₂ vol. %). A maximum of 3.92 eV was obtained from the films annealed at 300 °C in N₂:H₂ gas atmosphere (17.5 O₂ vol. %).     

Effect of substrate temperature on the adhesion properties of magnetron sputtered nano-composite Si-C-N hard thin films

The adhesion and film failure studies on nano-composite SiCN thin films on silicon, glass and steel have been carried out. It was observed that both coating as well as the substrate has an influence on the adhesion of film. The films on hard substrate Si failed adhesively whereas on softer substrate, steel, cohesive failure was observed. The measured critical load was around 18 N and 24 N for SiCN film on silicon and steel substrate respectively. A decrease in critical load and interface toughness with the increase of substrate temperature during deposition for glass and steel substrate was observed.     

沉积条件对RF反应溅射多晶ZnO薄膜结构的影响

采用ＲＦ反应溅射法在Ｓｉ（１１１）、玻璃衬底上制备了具有良好Ｃ轴承向的多晶ＺｎＯ薄膜。用ＸＲＤ分析了沉积条件（衬底温度、工作气体中的氧与氩气压比和衬底种类）对样品结构的影响,发现（１）薄膜的取向性随着衬底温或高而增强,超过４００℃后薄膜质量开始变差;（２）工作气体中氧与氩气压比（Ｐｏ２／ＰＡｒ）为２：３时,薄膜取向性最好;（３）薄膜晶粒尺寸１１－３４ｎｍ,相同沉积条件下,单晶硅衬底样品（００２）衍     

Influence of substrate temperature and bias voltage on the optical transmittance of TiN films

Titanium nitride (TiN) thin films were prepared by means of reactive DC sputtering on quartz and sapphire substrates. Structural, electrical and optical effects of deposition parameters such as thickness, substrate temperature, substrate bias voltage were studied. The effect of substrate temperature variations in the 100-300°C range and substrate bias voltage variations in the 0-200 V DC range for 45-180 nm thick TiN films were investigated. Temperature-dependent electrical resistivity in the 100-350 K range and optical transmission in the 300-1500 nm range were measured for the samples. In addition, structural and morphological properties were studied by means of XRD and STM techniques.The smoothest surface and the lowest electrical resistivity was recorded for the optimal samples that were biased at about V_s=−120 V DC. Unbiased films exhibited a narrow optical transmission window between 300 and 600 nm. However, the transmission became much greater with increasing bias voltage for the same substrate temperature. Furthermore, it was found that lower substrate temperatures produced optically more transparent films.Application of single layers of MgF₂ antireflecting coating on optimally prepared TiN films helped increase the optical transmission in the visible region to more than 40% for 45 nm thick samples.     

偏压对反应磁控溅射TiN薄膜结构以及性能的影响

本文采用直流反应磁控溅射技术,以Ar和N2为反应前驱气体制备了TiN功能装饰薄膜.重点研究了衬底负偏压对沉积TiN薄膜的色泽、性能及微结构的影响.采用台阶轮廓仪、X射线衍射仪、EDS能谱仪、纳米压痕仪等分析了薄膜的粗糙度、晶相、组分、纳米硬度以及弹性模量.结果表明,采用适宜的衬底负偏压调控轰击离子能量,能够有效阻止薄膜结构中空位以及缺陷的产生,从而有效避免薄膜表面的紫黑色氧化钛的生成,有利于表面光滑的金黄色TiN薄膜制备,同时使薄膜具备更优异的力学性能.实验结果还表明基体偏压可显著影响TiN薄膜的择优生长取向:随偏压增加,薄膜由(111)晶相择优生长转变为(200)晶相的择优生长,(200)晶相的薄膜比(111)晶相薄膜具有更佳的力学性能.     

Properties of RF magnetron sputtered indium tin oxide thin films on externally unheated glass substrate

Indium tin oxide (ITO) thin films were deposited by radio frequency (RF) magnetron sputtering onto glass substrates. The transparent and conducting ITO thin films were obtained on externally unheated glass substrate, without any post-heat treatment, and by varying the deposition process parameters such as the working pressure and the RF Power. The effect of the variation of the above deposition parameters on the structural, surface morphology, electrical, and optical properties of the thin films have been studied. A minimum resistivity of 2.36 × 10⁻⁴ Ω cm and 80% transmittance with a figure of merit 37.2 × 10⁻³ Ω⁻¹ is achieved for the thin films grown on externally unheated substrate with 75 W RF power and 0.5 mTorr working pressure.     

衬底温度对磁控溅射制备外延ZnO薄膜结构特性的影响

在不同的衬底温度下,采用磁控溅射方法在蓝宝石(0001)衬底上制备了外延生长的ZnO薄膜.采用原子力显微镜(AFM)、X射线衍射仪(XRD)、可见-紫外分光光度计系统研究了衬底温度对ZnO薄膜微观结构和光学特性的影响.AFM结果表明在不同村底温度制备的ZnO薄膜具有较为均匀的ZnO晶粒,且晶粒的尺寸随衬底温度的增加逐渐增大.XRD结果显示不同温度生长的ZnO薄膜均为外延生长,400℃生长的薄膜具有最好的结晶质量;光学透射谱显示在370nm附近均出现一个较陡的吸收边,表明制备的ZnO薄膜具有较高的质量,其光学能带隙随着衬底温度的增加而减小.     

磁控溅射CrNx薄膜的制备与力学性能

采用反应磁控溅射法在不同的氮分压下制备了一系列CrNx薄膜，并利用EDS和XRD表征了薄膜的成分和相组成，采用力学探针测量了薄膜的硬度和弹性模量。研究了氮分压对薄膜成分，相组成和力学性能的影响。结果表明，随氮分压的升高，薄膜的沉积速率明显降低，薄膜中的氮含量量增加，相应地，相组成从Cr Cr2N过渡到单相Cr2N,再逐步经Cr2N CrN过渡到单相CrN,并在Cr:N原子比为1：2和1：1时，薄膜的硬度出现极值（HV27．1GPa和HV26.8GPa),而薄膜的弹性模量则在Cr2N时呈现350GPa的最高值。