Effect of carrier gas on metal-organic chemical vapour deposition of aluminium from dimethylethylamine alane

The effect of carrier gas, such as H₂, He, and Ar, on the deposition rate, film morphology, resistivity, and chemical composition of Al thin film from dimethylethylamine alane (DMEAA) was investigated. The deposition rate was highest in H₂ carrier gas and lowest in Ar, when the substrate temperature is above 150 °C. The surface morphology of the film deposited in He carrier gas was rough and particles from gas phase reaction, were also observed on the film surface. The film deposited in He carrier gas had a higher resistivity than the films deposited in H₂ or Ar at the higher substrate temperature due to oxygen impurity incorporated in the film.     

Effects of the deposition temperature on the resistivity of copper films produced by low-pressure metal-organic chemical vapour deposition on a TiN barrier layer

Copper was deposited on to TiN by low-pressure metal-organic chemical vapour deposition, using hexafluoroacetylacetonate-Cu⁺¹-trimethylvinylsilane (hfacCu(I)TMVS) and argon carrier gas. The resistivity of the deposited copper films was investigated by observing the effects of the deposition temperature on the composition, microstructure and surface morphology of the copper films. The resistivity of the copper films decreases as the deposition temperature decreases. The copper films deposited at high temperatures, tend to contain the pores and or/ channels as well as carbon and oxygen, which results in the increase of the resistivity of the deposited films. The pores and/or channels come from the island-like growth of the copper films, while carbon and oxygen are due to the concurrent thermal decomposition of hfac during the disproportionation reaction between hfacCu(I) molecules.     

Effect of hydrogen content on the ZnO thin films on the surface of polyethylene terephthalate substrate through electron cyclotron resonance-metal organic chemical vapor deposition

Zinc oxide thin films were deposited on polyethylene terephthalate (PET) substrate by the electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) method at room temperature with the addition of hydrogen to the reaction gas. Diethyl zinc (DEZn) as the source precursor, O₂ as oxidizer and argon as carrier gas were used for the preparation of ZnO film. Scanning electron micrography and X-ray diffraction analyses revealed that the ZnO grains with size of ca. 20 nm had an elliptic cylindrical configuration and were highly c-axis-oriented. The hydrogen content strongly affected the crystallographic structure, electrical property, and composition, as well as the surface roughness of the zinc oxide films. The chemical composition and surface states of the films were further examined by RBS and XPS to find the reason for the different electrical resistivity with variation of H₂/Ar ratio. It can be concluded that hydrogen content plays an important role in increasing the Hall mobility, hole concentration, and electron concentration in our experimental range.     

Investigation of copper layers deposited by CVD using Cu(I)hfac(TMVS) precursor

Chemical vapour deposition (CVD) of copper on titanium-coated substrates was performed in a stainless steel reactor using copper(I) hexafluoroacetylacetonate trimethylvinylsilane (Cu(I)hfac(TMVS)) as a precursor and nitrogen (N₂) as carrier gas. Film resistivity, film composition and surface morphology were studied in relation to deposition temperature, process pressure and process gas flow ratio. The lowest resistivity value obtained was around 2 μΩcm. In addition, cross-sectional examination of the copper films, using a LEO SEM imaging system, indicated increased film porosity at higher deposition temperatures. An optimum carrier gas flow rate was determined: higher carrier gas flow rates caused excessive dilution of the copper precursor, whilst lower carrier gas flow rates weakened the transport of the copper precursor to the substrate. XRD data revealed formation of copper oxide (Cu₂O) if annealing temperatures exceeded 450∘C for a period of 30 min.FIB/TEM imaging revealed that CVD copper offers better conformality and viafilling than PVD copper in trenches 0.25 μm wide and 0.5 μm deep. CVD copper layers, passivated by a spin-on-glass dielectric, were shown to have reduced surface migration of copper atoms, compared to unpassivated layers. Copper films with a predominantly (111) orientation were found to exhibit a longer electromigration lifetime than copper films with mixed (111) and (200) orientations.     

射频溅射工艺参数对AZO薄膜结构和性能的影响

采用射频磁控溅射法制备了掺铝氧化锌(AZO)薄膜,研究了衬底温度及溅射工作压强对沉积薄膜的晶体结构、表面形貌及电学性能的影响。结果显示,随衬底温度增加,薄膜的结晶结构发生显著变化,而溅射工作气压增加主要影响沉积薄膜(103)面与(002)面的相对强度。薄膜的表面形貌受温度影响严重,而气压对形貌的影响相对较小。衬底温度增加,薄膜的电阻率急剧降低,迁移率和载流子浓度都显著增加,而工作气压增加则导致电阻率先减小后增大。     

Influence of the nitrogen partial pressure on the properties of d.c.-sputtered titanium and titanium nitride films

The properties of titanium and titanium nitride films deposited onto biased substrates in a d.c. sputtering system were studied as a function of the partial nitrogen pressure. The deposition rate was deduced from film thickness measurements. The film composition was determined by Rutherford backscattering analysis and the structure was studied using X-ray diffraction. The resistivity was measured by the four-probe method and the temperature coefficient of resistivity (TCR) was determined in the temperature range from ?196 to 25 °C.Around a critical nitrogen pressure p_c of 4 × 10^-2 Pa the deposition rate decreases rapidly, the film structure changes from h.c.p. titanium to nearly stoichiometric f.c.c. TiN. At the same pressure, the film resistivity and the TCR present minimum values.A general sputtering model which takes into account the gettering action of the deposited material is proposed. This model allows the calculation of the surface coverage of the target by the reactive gas or the metallic compound and the determination of the deposition rate as a function of the reactive partial pressure. A good agreement is found with the deposition rates measured experimentally.     

One-step production of superhydrophobic coatings on flat substrates via atmospheric Rf plasma process using non-fluorinated hydrocarbons

This paper describes the direct deposition of hydrocarbon coatings with a static water contact angle higher than 150 using simple C6 hydrocarbons as a reactive gas in helium plasma generated in ambient air without any preroughening of the silicon (100) substrate. The film morphology and hydrophobicity are found to strongly depend on the structure of the reagent hydrocarbon. The films deposited with n-hexane and cyclohexane exhibited relatively smooth morphology and the water contact angle was only ～95°, similar to polypropylene. When benzene was used as a main reactive gas, the deposited film surface showed nanoscale textured morphology and superhydrophobicity with a water contact angle as high as 167°. Because the plasma is generated in air, all films show some degree of oxygen incorporation. These results imply that the incorporation of a small amount of oxygenated species in hydrocarbon films due to excitation of ambient air is not detrimental for superhydrophobicity, which allows the atmospheric rf plasma with the benzene precursor to produce rough surface topography needed for superhydrophobicity.     

The effect of hydrogen annealing on the molybdenum doped ZnO thin film

The electrical characteristics of hydrogen annealing on the molybdenum doped ZnO (MZO) thin film were discussed in the paper. The MZO film was deposited by an radio frequency sputtering, then it was annealed in hydrogen with a microwave plasma chemical vapor deposition system. The resistivity of MZO was decreased from 1.1 × 10^?2 to 9.5 × 10^?3 Ω cm after the hydrogen annealing. Improvements of the electrical properties are both due to the defects repairing through annealing and hydrogen doping effects of the MZO thin film. The higher temperature annealed MZO film shows slightly lower transmittance which is due to the higher carrier concentration.     

Ion beam deposition of α-Ta films by nitrogen addition and improvement of diffusion barrier property

Ta thin films were deposited on Si (100) substrates by an ion beam deposition method at various substrate bias voltages under Ar + N₂ atmosphere with different pressure ratios of Ar and N₂. The effects of nitrogen pressure in the plasma gas and the substrate bias voltage on the surface morphology, crystalline microstructure, electrical resistivity and diffusion barrier property were investigated. It was found that the fraction of a metastable β-phase in the Ta film deposited at the substrate bias voltage of − 50 V films decreased by adding nitrogen gas, while the α-Ta phase became dominant. As a result, the Ta films deposited at the substrate bias voltage of − 50 V under Ar (9 Pa) + N₂ (3 Pa) atmosphere showed a dominant α-phase with good surface morphology, low resistivity, and superior thermal stability as a diffusion barrier.     

Effects of oxygen gas flow rate and ion beam plasma conditions on the opto-electronic properties of indium molybdenum oxide films fabricated by ion beam-assisted evaporation

The purpose of the present work is to experimentally study the effects of the oxygen gas flow rate and ion beam plasma conditions on the properties of indium molybdenum oxide (IMO) films deposited onto the polyethersulfone (PES) substrate. Crystal structure, surface morphology, and optoelectronic properties of IMO films are examined as a function of oxygen gas flow rate and ion beam discharge voltage.Experimental results show that the IMO films consist of a cubic bixbyite B-In₂O₃ single phase with its crystal preferred orientation alone B(222). Mo⁶⁺ ions are therefore considered to partially substitute In³⁺ sites in the deposit. Under-controlled ion bombardment during deposition enhances the reaction among those arriving oxygen and metal ion species to condense into IMO film and facilitates a decreased surface roughness of IMO film. The film with ultimate crystallinity and the lowest surface roughness is obtained when the oxygen flow rate of 3 sccm and the discharge voltage of 110 V are employed. This results in the lowest electrical resistivity due mainly to the increased Hall mobility and irrelevant to carrier concentration. The lowest electrical resistivity of 8.63 × 10^− 4 ohm-cm with a 84.63% transmittance at a wavelength of 550 nm can be obtained, which satisfies the requirement of a flexible transparent conductive polymer substrate.     

C/C复合材料的非晶SiO_2涂层制备及其生物活性

以正硅酸乙酯(TEOS)为前驱体,N_2为载气,在C/C复合材料表面通过低压化学气相沉积(LPCVD)得到非晶SiO_2涂层。研究了沉积温度对涂层成分、涂层形貌和沉积速率的影响。通过XRD、XPS、FTIR、SEM和EDS等测试手段,对涂层的成分、微观形貌以及模拟体液浸泡后材料的生物活性进行了表征和分析。实验结果表明:涂层的主要物相为非晶SiO_2;模拟体液浸泡至35天,样品表面生成类骨羟基磷灰石,与未涂层的C/C复合材料相比,表明非晶SiO_2涂层具有良好的生物活性。随着沉积温度的增加,沉积速率增大,涂层包覆更加完整;SiO_2颗粒由不规则形状转变为规则的球形,最后转变成多边形。     

PECVD法制备非晶硅薄膜及光电性能研究

采用等离子体增强化学气相沉积（PECVD）方法在玻璃衬底上制备出非晶硅薄膜,利用正交试验法对射频功率、气体总压、硅烷比例、沉积时间、退火温度、退火时间因素进行了研究,对透过率和电阻率进行了分析,结果表明,采用PECVD法成功制备出非晶硅薄膜。正交实验表的分析得知,气体总压对透过率影响最大;硅烷比例对电阻率影响最大。制备非晶硅薄膜的优化条件为：射频功率30W、气体总压100Pa,硅烷5％、沉积时间5min、退火温度300℃、退火时间45min。非晶硅薄膜的光透过率93．18％,电阻率为13．238kΩ·cm。     

The effect of argon pressure, residual oxygen and exposure to air on the electrical and microstructural properties of sputtered chromium thin films

Chromium thin films were deposited on SiO₂/Si wafers using two sputtering systems with different levels of cleanliness, and at argon sputtering pressures varying between 0.13 and 0.93 Pa. Films from the two systems grown under identical sputtering conditions had significantly different resistivity values that are shown to be due to differences in residual oxygen in the chambers. Electrical transport measurements were conducted on the series of grown films to investigate the influence of argon pressure on film electrical resistivity. The films morphology, microstructure and composition were characterized using scanning electron microscopy and X-ray photoelectron spectroscopy. Significant differences were found in Cr thin films sputtered at different sputtering pressures; differences in resistivity performance and microstructure were noted. This change was shown to be due to the transition from porous structure to a denser microstructure. The Cr films sputtered at high pressure contained large quantities of oxygen when exposed to air. Some of the oxygen is added to the film during the deposition depending on the deposition rate and the base pressure of the sputtering system. The rest is incorporated into the film once it is exposed to air. The amount of oxygen added at this stage depends on the structure of the film and would be minimal for the films deposited at low sputtering pressures.     

Structure and electrical properties of ITO thin films deposited at high rate by facing target sputtering

High rate deposition of ITO thin films at a low substrate temperature was attempted by using a facing target sputtering (FTS) system. Deposition rate as high as 53 nm/min was realized on polycarbonate film substrate of 80-μm thickness. When the film was deposited at a deposition rate above 80 nm/min, polycarbonate film substrate was thermally damaged. The film deposited by FTS has much smaller compressive film stress than the film deposited by conventional magnetron sputtering. The film stress was reduced significantly by increasing the sputtering gas pressure and stress-free films can be obtained by adjusting the sputtering gas pressure. This may be mainly caused by the fact that bombardment by high energy negative oxygen ions to substrate surface during deposition can be completely suppressed in the FTS. Film structure and electrical properties changed little with substrate position, and uniform films were obtained by the FTS.     

Growth and characterization of diamond films deposited at high-pressure using a low-power microwave plasma reactor

Diamond films were deposited on molybdenum substrates from mixtures of methane diluted in hydrogen using a high-pressure microwave plasma reactor. In this reactor, a compressed waveguide structure was used to increase the electric field strength, and accordingly the reactor was able to operate stably with low gas flow rate and microwave power. The films deposited on 12 mm diameter substrates were characterized by film morphology, Raman spectra, growth rate and crystalline quality. The morphology of diamond films deposited in this reactor depends mainly on the substrate temperature. When the deposition pressure was 48 kPa and microwave power was only 800 W, high quality diamond films could be uniformly deposited with a growth rate around 20 μm/h.     

Growth behavior and surface topography of different silane coupling agents adsorbed on the silicon dioxide substrate (0001) for vapor phase deposition

The growth behavior and surface topography of the deposited films formed from silane coupling agents on silicon dioxide substrate (0001) via vapor phase deposition was investigated using atomic force microscopy (AFM). The surface topography of the films adsorbed on the silicon dioxide substrates is dissimilar with different silane coupling agents and different deposition conditions: (1) the films adsorbed on the silicon dioxide substrate become smoother with the increasing temperature of the silicon dioxide substrate; (2) the surface roughness of the films increases with the increasing concentration of the silane coupling agent solutions; (3) with the increasing temperature of the carrier gas, the surface roughness of the films decreases firstly and then increases; (4) with the increasing time of deposition, the surface roughness of the films increases firstly, then decreases and subsequently increases again. In experiments, the films adsorbed on the silicon dioxide substrate was rinsed ultrasonically with toluene, the results indicate that the silane coupling agent adsorbed on the substrate by physisorption and chemisorption: the chemisorbed coupling agents present island morphology and the physisorbed coupling agents are deposited on the substrate between the islands to decrease the surface roughness of the film.     

Electrical conduction and transmission electron microscopy studies of CdSe0.8Te0.2 thin films

Electrical resistance of CdSe_0.8Te_0.2 thin films were found to be dependent on various film parameters such as substrate temperature, film thickness, deposition rate and post-deposition heat treatment in different environments. A decrease in film resistivity was observed for thicker films and for those heat treated in vacuum. Films deposited at higher substrate temperatures and faster rates showed an increase in film resistivity. A spectrum of activation energies was observed in the films which fell within either of the activation energies observed in CdSe or CdTe films. Films heated in an oxygen environment showed an increase in film resistivity with a different activation energy. Transmission electron microscopy (TEM) of the films showed an improvement in crystallinity with increasing film thickness and substrate temperature, and a reduction in crystallinity with increasing deposition rate.     

Effect of temperature on the properties of Al:ZnO films deposited by magnetron sputtering with inborn surface texture

Al:ZnO (AZO) films were deposited on glass substrate with inborn surface texture by magnetron sputtering at a power density as high as 7 W/cm². The sputtering parameters, such as argon working pressure and substrate temperature were varied from 1.0 to 6.0 Pa and from room temperature to 500 °C, respectively. All the films exhibited perfect (002) orientations with very weak (004) peaks measured by X-ray diffraction. A linear relationship between the growth rate of AZO film and working pressure was found. The AZO film with best electrical properties of all films obtained at room temperature was deposited at working pressure of 2.0 Pa. And the root-mean-square roughness tested by atomic force microscopy was 37.50 nm, which indicated that surface texture was successfully fabricated without further etching process. For higher substrate temperature a decrease in the resistivity was observed due to an increase in the mobility and the carrier concentration. Resistivity low as 9.044 × 10⁻⁴ ohm/cm was obtained at 500 °C and 2.0 Pa, the corresponding mobility and carrier concentration were 20.45 m²/Vs and 3.379 × 10²⁰/cm³, respectively. The grain size and the surface texture size tested by scanning electron microscopy also peaked at 500 °C. All the films showed a relatively high transmittance about 80%.     

用ECRCVD方法制备优质氮化硅钝化膜

利用电子回旋共振等离子体化学气相沉积(ECR—CVD)技术，以SiH4和N2为反应气体进行了氮化硅钝化薄膜的低温沉积技术的研究。采用原子力显微镜、傅立叶变换红外光谱和椭圆偏振光检测等技术对薄膜的表面形貌、结构、厚度和折射率等性质进行了测量。结果表明，采用ECR—CVD技术能够在较低的衬底温度条件下以较高的沉积速率制备厚度均匀的氮化硅薄膜，薄膜中H含量很低。薄膜沉积速率随微波功率和混合气体中硅烷比例的增加而增大。折射率随微波功率的增大而减小，随混合气体中硅炕比例的增大而增大。在相同气体混合比和微波功率条件下，较高衬底温度条件下制备的薄膜折射率较大。     

Structural and morphological investigations on DC-magnetron-sputtered nickel films deposited on Si (100)

Pure nickel thin films were deposited on Si (100) substrates under different conditions of sputtering using direct current magnetron sputtering from a nickel metal target. The different deposition parameters employed for this study are target power, argon gas pressure, substrate temperature and substrate-bias voltage. The films exhibited high density of void boundaries with reduction in <111> texture deposited under high argon gas pressures. At argon gas pressure of 5 mTorr and target power of 300 W, Ni deposition rate was ~40 nm/min. In addition, coalescence of grains accompanied with increase in the film texture was observed at high DC power. Ni films undergo morphological transition from continuous, dense void boundaries to microstructure free from voids as the substrate-bias voltage was increased from −10 to −90 V. Furthermore, as the substrate temperature was increased, the films revealed strong <111> fiber texture accompanied with near-equiaxed grain structure. Ni films deposited at 770 K showed the layer-by-layer film formation which lead to dense, continuous microstructure with increase in the grain size.