Effects of substrate temperature on electrical and structural properties of copper thin films

This paper addresses the effects of substrate temperature on electrical and structural properties of dc magnetron sputter-deposited copper (Cu) thin films on p-type silicon. Copper films of 80 and 500 nm were deposited from Cu target in argon ambient gas pressure of 3.6 mTorr at different substrate temperatures ranging from room temperature to 250 °C. The electrical and structural properties of the Cu films were investigated by four-point probe and atomic force microscopy. Results from our experiment show that the increase in substrate temperature generally promotes the grain growth of the Cu films of both thicknesses. The RMS roughness as well as the lateral feature size increase with the substrate temperature, which is associated with the increase in the grain size. On the other hand, the resistivity for 80 nm Cu film decreases to less than 5 μΩ-cm at the substrate temperature of 100 °C, and further increase in the substrate temperature has not significantly decreased the film resistivity. For the 500 nm Cu films, the increase in the grain size with the substrate temperature does not conform to the film resistivity for these Cu films, which show no significant change over the substrate temperature range. Possible mechanisms of substrate-temperature-dependent microstructure formation of these Cu films are discussed in this paper, which explain the interrelationship of grain growth and film resistivity with elevated substrate temperature.     

Indium doped zinc oxide thin films deposited by ultrasonic spray pyrolysis technique: Effect of the substrate temperature on the physical properties

Indium doped zinc oxide (ZnO:In) thin solid films were deposited on soda-lime glass substrates by the ultrasonic spray pyrolysis technique. The effect of the substrate temperature on the electrical, morphology, and optical characteristics of ZnO:In thin films was studied. It was found that, as the substrate temperature increases, the electrical resistivity decreases, reaching a minimum value in the order of 7.3×10⁻³ Ω cm, at 415 °C. Further increase in the substrate temperature results on an increment on the electrical resistivity of the thin solid films. All the samples were polycrystalline with a well-defined wurtzite structure. The preferred growth shows a switching from a random orientation at low substrates temperatures to (0 0 2) in the case of films deposited at the highest substrate temperature used. As the substrate temperature increases, the corresponding surface morphology changes from an almost faceted pyramidal to round-shaped form. The optical transmittance of the films in a interval of 400 to 700 nm is around 70%, with a band gap value in the order of 3.45 eV.     

Effect of the substrate temperature on the electrical and structural properties of spray-deposited SnO2:F thin films

SnO₂:F thin films were prepared by the spray pyrolysis (SP) technique at substrate temperature in the range 360–480 °C. The effect of varying the substrate temperature on the electrical and structural properties of the films was investigated by studying the I–V characteristics, the X-ray diffraction patterns (XRD), and the scanning electron microscope images (SEM). The I–V characteristics of the films were improved by increasing the substrate temperature, i.e. the resistivity of the films had decreased from 98 to 0.22 Ω cm. The X-ray diffraction patterns taken at 400 and 480 °C showed that the films are polycrystalline and two directions of crystal growth appeared in the difractogram of the film deposited at the lower substrate temperature, which correspond to the reflections from the (1 1 0) and (2 0 0) planes. With the increase in the substrate temperature a new direction of crystal growth appeared, which corresponds to the reflection from the (1 0 1) plane. Also the (1 1 0) and (2 0 0) lines were slightly grown at the higher substrate temperature, which means the crystal growth was enhanced and the grain size had increased. The SEM images confirmed these results and showed larger grains and more crystallization for the higher substrate temperature too.     

Selective orientation of discotic films by interface nucleation

Thin films deposited from solution by the hollow capillary writing technique exhibit macroscopic uniaxial grains with an in-plane arrangement of discotic stacks. We report a method to change the orientation of thin films from in-plane to homeotropic (discotic columns perpendicular to the substrate). It is observed that annealing of open supported films at a temperature 25 °C below the equilibrium LC/isotropic phase boundary induces homeotropic alignment, while rapid cooling leads to predominantly in-plane alignment. A model based on heterogeneous nucleation at the film/substrate interface accounts for the experimental observations.     

The influence of substrate temperature on the structural and optical properties of ZnS thin films

Thin films of ZnS were deposited on soda lime glass substrates by a modified close-space sublimation technique. The change in optical and structural properties of the films deposited at various substrate temperatures (150–450°C) was investigated. X-ray diffraction spectra showed that films were polycrystalline in nature having cubic structure oriented only along (111) plan. The crystallinity of films increased with the substrate temperature up to 250°C. However, crystallinity decreased with further increase of substrate temperature and films became amorphous at 450°C. The atomic force microscopy data revealed that the films become more uniform and dense with the increase of substrate temperature. Optical properties of the films were determined from the transmittance data using Swanepoel model. It was observed that the energy band gap is increased from 3.52 to 3.65 eV and refractive index of the films are decreased with the increase of substrate temperature. Moreover, considerable improvement in blue response of the films was noticed with increasing substrate temperature.     

Impact of substrate temperature on the structural,optical and electrical properties of thermally evaporated SnS thin films

Tin Sulfide thin films were deposited on soda lime glass substrates at three different substrate temperatures using thermal evaporation technique. The impact of substrate temperature on the deposited films has been studied thoroughly. Surface morphology was modified with the substrate temperature. XRD spectra shows orthorhombic end-centered type SnS having (1 1 0) orientation. The crystallite size increases with the increase in the substrate temperature. At a high substrate temperature (450 °C) small grains form on the surface and crystallinity decreases. The effect of substrate temperature on optical and electrical properties has been studied using UV–Vis–NIR Spectrophotometer and Hall effect respectively. With the increase in the substrate temperature there is a substantial decrease in the transmittance and bandgap value. Refractive index (n), dielectric constant (ε₁) and extinction co-efficient (k) have also been calculated for different substrate temperatures.     

Local crystal structural modifications in pulsed laser deposited high-k dielectric thin films on silicon and germanium

The thin film growth conditions are correlated with the local structures formed in Hf_xZr_1−xO₂ (x=0.0–1.0) high-k dielectric thin films on Si and Ge substrates during deposition. Pulsed laser deposition (PLD) technique has been used in the synthesis of the thin films with systematic variations of substrate temperature, Zr content of the targets and substrate selection. The local structural information acquired from extended X-ray absorption spectroscopy (EXAFS) is correlated with the thin film growth conditions. The response of the local structure around Hf and Zr atoms to growth parameters was investigated by EXAFS experiments performed at the National Synchrotron Light Source of Brookhaven National Laboratory. The competing crystal phases of oxides of Hf were identified and the intricate relation between the stabilized phase and the parameters as: the substrate temperature; Hf to Zr ratio; have been revealed. Specifically, HfO₂ thin films on Si(1 0 0) exhibit a tetragonal to monoclinic phase transformation upon increase in the substrate temperature during deposition whereas, HfO₂ PLD films on Ge(1 0 0) substrates remain in tetragonal symmetry regardless of the substrate temperature.     

Properties of ZnO/Cu/ZnO multilayer films deposited by simultaneous RF and DC magnetron sputtering at different substrate temperatures

ZnO/Cu/ZnO transparent conductive multilayer films are prepared by simultaneous RF sputtering of ZnO and DC sputtering of Cu. The properties of the multilayer films are studied at different substrate temperatures. Sheet resistance of the multilayer film decreased initially with increase of substrate temperature and increased further with increase of substrate temperature beyond 100 °C. However, transmittance of the multilayer film increased with increase of substrate temperature. Good transparent conductive film of sheet resistance 9.3 Ω/sq and transmittance of 85% was found at a substrate temperature of 100 °C. The performance of the multilayer film was evaluated using a figure of merit. The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.     

Piezoelectric zinc oxide by electrostatic spray pyrolysis

Zinc oxide (ZnO) possesses many interesting properties, such as a wide energy band gap, large photoconductivity, and high excitonic binding energy. Piezoelectric (ZnO) film has a high electro-mechanical coupling coefficient, which makes it a promising material for high frequency and low surface acoustic wave (SAW), bulk acoustic wave, and microelectromechanical system devices. In this work, we present the first results obtained for piezoelectric ZnO thin films prepared on corning 7059 glass substrate by electrostatic spray pyrolysis (ESP), a simple, cheap and efficient technique not widely used for ZnO deposition, using zinc nitrate in a mixture of deionised water and isopropyl alcohol. The structural morphologic and optical properties of the films have been studied and the effect of the preparation conditions, such as substrate temperature and substrate-nozzle distance, discussed. Highly c-axis preferred orientation, which is critical for piezoelectric applications (ultrasonic oscillators and transducers devices), ZnO thin films are obtained at 350 °C growth temperature and at 4.5 cm substrate-nozzle distance.     

Effect of annealing temperature on structural,electrical and optical properties of spray pyrolytic nanocrystalline CdO thin films

Nanocrystalline CdO thin films were prepared onto a glass substrate at substrate temperature of 300 °C by a spray pyrolysis technique. Grown films were annealed at 250, 350, 450 and 550 °C for 2.5 h and studied by the X-ray diffraction, Hall voltage measurement, UV-spectroscopy, and scanning electron microscope. The X-ray diffraction study confirms the cubic structure of as-deposited and annealed films. The grain size increases whereas the dislocation density decreases with increasing annealing temperature. The Hall measurement confirms that CdO is an n-type semiconductor. The carrier density and mobility increase with increasing annealing temperature up to 450 °C. The temperature dependent dc resistivity of as-deposited film shows metallic behavior from room temperature to 370 K after which it is semiconducting in nature. The metallic behavior completely washed out by annealing the samples at different temperatures. Optical transmittance and band gap energy of the films are found to decrease with increasing annealing temperature and the highest transmittance is found in near infrared region. The refractive index and optical conductivity of the CdO thin films enhanced by annealing. Scanning electron microscopy confirms formation of nano-structured CdO thin films with clear grain boundary.     

Formation of Cu<Subscript>2</Subscript>O and ZnO Crystal Layers by Magnetron Assisted Sputtering and Their Optical Characterization

Copper (I) oxide and zinc oxide films are formed on silicon and glassy quartz substrates by magnetron assisted sputtering. The thickness of the films is tens and hundreds of nanometers. The films are grown at different substrate temperatures and different oxygen pressures in the working chamber. The film samples are studied by the X-ray diffraction technique, scanning electron microscopy, and optical methods. It is established that an increase in the substrate temperature yields a change in the surface morphology of copper (I) oxide films towards the formation of well-pronounced crystallites. The reflectance and Raman spectra suggest that the quality of such films is close to that of bulk Cu₂O crystals produced by the oxidation of copper. As concerns ZnO films, an increase in the substrate temperature and an increase in the partial oxygen pressure make it possible to produce films, for which a sharp exciton structure is observed in the reflectance spectra and the emission of excitons bound at donors is observed in the luminescence spectra.     

基片温度对电子束蒸发的ZnS薄膜性能的影响

采用电子束蒸发在不同基片温度下沉积ZnS薄膜,研究了基片温度对薄膜性能的影响.结果表明:不同基片温度下沉积的ZnS薄膜均呈多晶状态,为体心立方(闪锌矿)结构的β-znS,并具有明显的(111)面择优取向,导电类型为n型.随着成膜时基片温度的提高,薄膜结晶度越来越好,透过率增大,载流子浓度增大,而电阻率减小.     

Role of substrate temperature on MoO3 thin films by the JNS pyrolysis technique for P–N junction diode application

Molybdenum trioxide (MoO₃) thin films were prepared at different substrate temperatures from 350 to 500 °C by the jet nebulizer spray (JNS) pyrolysis technique. The effect of the substrate temperature on the structural, optical and electrical properties of MoO₃ films was characterized. The XRD pattern exposed that the crystallite size of the films increases with the increase in the substrate temperature. The SEM images showed the conversion of nanorods to sub-microsized plate-like structures by increasing the substrate temperature. The EDX analysis confirmed the presence of Mo and O elements. The UV–vis results revealed that the band gap obtained shows a decreasing trend on increasing the substrate temperature. The FTIR spectra confirmed the formation of MoO₃. The dc electrical studies portrayed the minimum activation energy of 0.064 eV obtained for higher substrate temperature. The P–N diode of p-Si/n-MoO₃ was fabricated at the substrate temperature of 500 °C. The diode parameters such as ideality factor (n), barrier height (Φ_b) and reverse saturation current (I₀) values were calculated in darkness and under different light sources (Halogen and Metal halide lamps).     

循环刻蚀工艺对金刚石膜形貌和电阻率的影响

为了制备新型金刚石薄膜辐射剂量计,针对目前金刚石薄膜质量较差,难于满足辐射剂量计要求的问题,采用微波等离子体CVD法,研究了循环刻蚀生长阶段工艺参数(甲烷浓度,基片温度)和刻蚀方法对薄膜形貌、电阻率的影响。结果表明,循环刻蚀生长有利于提高金刚石薄膜的纯度和取向性。当?(甲烷)为0.34%,基片温度为960℃时,可获得[100]晶面取向的、电阻率达1011Ω·cm的金刚石膜,和采用常规工艺所得金刚石薄膜相比,其电阻率提高了3个数量级。     

Synthesis and gas sensing behavior of nanostructured V2O5 thin films prepared by spray pyrolysis

Nanocrystalline vanadium pentoxide (V₂O₅) thin films have been deposited by a spray pyrolysis technique on preheated glass substrates. The substrate temperature was changed between 300 and 500 °C. The structural and morphological properties of the films were investigated by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The influence of different substrate temperatures on ethanol response of V₂O₅ has also been investigated. XRD revealed that the films deposited at T_pyr=300 °C have low peak intensities, but the degree of crystallinity improved when the temperature was increased to 500 °C and films had orthorhombic structures with preferential orientations along the (0 0 1) direction. The fractal analysis showed a decreasing trend versus the pyrolysis temperature. Sensing properties of the samples were studied in the presence of ethanol vapor. The operating temperature of the sensor was optimized for the best gas response. The response increased linearly with different ethanol concentrations. It was found that films deposited at the lowest substrate temperature (300 °C) had the highest sensing response to ethanol.     

用脉冲激光沉积方法制备的ZnO薄膜的结构及光致发光特性

在从室温到800℃的温度范围内,用脉冲激光沉积方法在Al₂O₃（0001）衬底上制备了ZnO薄膜。采用X射线衍射仪、原子力显微镜以及荧光光谱仪分别研究了衬底温度对ZnO薄膜表面形貌、结晶质量和光致发光特性的影响。X射线衍射仪和原子力显微镜的结果表明,当衬底温度从室温升高到400℃时,ZnO薄膜的结构及结晶质量逐渐提高,而当衬底温度超过400℃时,其结构和结晶质量变差;在400℃下生长的ZnO薄膜具有最佳的表面形貌和结晶质量。室温光致发光的测量结果表明,400℃下生长的ZnO薄膜的紫外发光强度最强,且发光波长最短（386 nm）。     

衬底温度对反应磁控溅射制备AlN压电薄膜的影响

采用反应磁控溅射法在Si(111)衬底上沉积了AlN薄膜。XRD分析表明,在5种温度下,AlN均以(100)面取向,衬底温度的提高有利于薄膜结晶性的改善,在600℃以上时AlN中Al—N0键断裂,仅出现(100)衍射峰。AFM分析显示,在600℃时平均晶粒尺寸90nm,Z轴最高突起仅为23nm。     

Growth of AlN Films as a Function of Temperature on Mo Films Deposited by Different Techniques

The authors investigated the combined influences of substrate temperature and methods for preparing underlying Mo electrodes on the crystallinity, morphology, and electrical properties of AlN films using x-ray diffraction, scanning electron microscopy, and a network analyzer, respectively. The substrate temperature of the AlN films was varied from 20°C to 600°C. The underlying Mo electrodes were deposited by direct-current (DC) and radiofrequency (RF) sputtering techniques. A change in the AlN crystallites varied with the substrate temperature and differed for DC- and RF-sputtered Mo bottom electrodes. With increasing substrate temperature, the preferred orientation of AlN films on DC-sputtered Mo bottom electrodes varied from the $ \left( {10\overline{1} 0} \right) $ orientation to the (0002) orientation. The $ \left( {10\overline{1} 0} \right) $ orientation did not appear in the AlN films on RF-sputtered Mo bottom electrodes at low substrate temperature (20°C). The optimum substrate temperature for depositing (0002)-oriented AlN on Mo films was 400°C. At this substrate temperature, AlN films deposited on RF-sputtered Mo bottom electrodes exhibited better crystalline quality and greater frequency response with only one resonance peak compared with DC-sputtered Mo bottom electrodes. The cause of these phenomena is also discussed.     

Influence of substrate temperature on the deposition and structural properties of μc-Si: H thin films fabricated with VHF-PECVD

With in situ optical emission spectroscopy (OES) diagnosis on VHF-generated H₂+SiH₄ plasmas, and with the measurements of deposition rate and structure of μc-Si: H thin films fabricated with VHF-PECVD technique at different substracte temperature, influence of substrate temperature on the deposition of μc-Si: H thin film and on its structural properties have been investigated. The results show that with the increase of substrate temperature, the crystalline volume fraction Xc and average grain size d are enhanced monotonously, but the deposition rate increases firstly and then decreases. The optimized substrate temperature for (μc-Si: H thin films deposition under our current growth system is about 210 °C, at which deposition rate 0.8 nm/s of μc-Si: H thin film with Xc?60% and d?9 nm can be obtained.     

Stacked CMOS circuits integrated in laser-recrystallized silicon films

Laser-recrystallized poly-silicon films are used as a substrate for the integration of MOS transistors and CMOS circuits. Ring oscillators and frequency divider circuits up to 100 transistors operate well with a yield of about 80%. For the integration of stacked CMOS circuits already tested bulk structures are covered with a dielectric layer and a poly-silicon film which is recrystallized at low temperature. The SOI integration technique, with a maximum temperature treatment of 960°C, is employed to manufacture the second active area as a 3-D technology. After the integration process SOI and bulk CMOS transistors operate independently at two different active levels.