Characteristics of ZnO thin films prepared by radio frequency magnetron sputtering

We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto Langasite substrates at 200 °C through radio frequency magnetron sputtering with an radio frequency power at 200 W in an O₂/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The deposited film featured a polycrystalline nature, with (1 0 0), (0 0 2), and (1 0 1) peaks of hexagonal zinc oxide at 31.75°, 34.35°, and 36.31°. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (0 0 2) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement technique, the hardness and Young’s modulus of ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h. In addition, surface acoustic wave properties of ZnO thin films were also presented.     

递进式脉冲激光沉积CN_x薄膜的组织结构与摩擦学特性

采用脉冲激光沉积法(PLD)在不同激光通量下烧蚀CNx靶,在单晶硅基底上沉积CNx薄膜。利用扫描电子显微镜(SEM)、X射线能谱仪(EDS)、X射线光电子谱仪(XPS)等对薄膜的形貌、化学成分和微观结构进行了表征。采用球-盘式磨损试验机在大气(相对湿度48%～54%)环境下测试了薄膜的摩擦学特性。结果表明,递进式PLD技术可显著提高CNx薄膜的含氮量。当激光通量从5.0J/cm2提高至10.0J/cm2时,薄膜含氮原子数分数由23.8%上升至29.9%,膜中N-sp2 C键的含量上升,N-sp3 C键和sp3 C-C键的含量下降,薄膜的磨损率从2.1×10-15 m3/(N.m)上升至9.0×10-15 m3/(N.m)。摩擦系数为0.15～0.23,激光通量5.0J/cm2沉积的薄膜有最佳摩擦学性能。     

Oxynitride gate dielectric prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride

Thin oxynitride gate dielectric films were prepared by thermal oxidation of low-pressure chemical vapor deposition silicon-rich silicon nitride at temperature ranging 850–1050 °C. X-ray photoelectron spectroscopy results indicate that the conversion of the as-deposited silicon nitride into oxynitride with different composition or oxide is feasible and the process is governed by the oxidation temperature. For sample oxidized at 1050 °C for 1 h, the nitride film was converted into silicon dioxide with 7 at.% of nitrogen at the interface and the leakage current density can be reduced by several orders of magnitude. By measuring the leakage current, the barrier height (extracted from Fowler–Nordheim plot) at the dielectric/Si interface is found to be in the range of 1.14–3.08 eV for the investigated samples.     

Growth of lanthanum oxide films for application as a gate dielectric in CMOS technology

We have investigated properties of insulating lanthanum oxide (La₂O₃) films in connection with the replacement of silicon oxide (SiO₂) gate dielectrics in new generation of CMOS devices. The La₂O₃ layers were grown using metal organic chemical vapour deposition (MOCVD) at 500 °C. X-ray diffraction analysis revealed polycrystalline character of the films grown above 500 °C. The X-ray photoemission spectroscopy detected lanthanum carbonate as a principal impurity in the films and lanthanum silicate at the interface with silicon. Density of oxide charge, interface trap density, leakage currents and dielectric constant ( κ) were extracted from the C-V and I-V measurements. Electrical properties, in particular dielectric constant of the MOCVD grown La₂O₃ are discussed with regard to the film preparation conditions. The as grown film had κ11. Electrical measurements indicate possible presence of oxygen vacancies in oxide layer. The O₂-annealed La₂O₃ film had κ17.     

热丝化学气相沉积法低温制备纳米晶态碳化硅薄膜

采用热丝化学气相沉积(HFCVD)技术以甲烷(CH4)和硅烷(SiH4)作为源反应气体在Si(111)衬底上合成了纳米晶态SiC薄膜。通过X射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)以及光致发光(PL)检测技术对薄膜的晶体结构、表面形貌和PL特性进行了分析和表征。结果表明，在较低的衬底温度下所沉积的薄膜是由镶嵌于非晶SiC网络中的晶态纳米SiC构成。纳米晶粒平均尺寸约为6nm。室温下用HeCr激光激发样品，观到薄膜发出波长位于400～550nm范围内可见光辐射。     

Preparation and gas-sensing properties of α-Fe2O3 thin films

Haematite (α-Fe₂O₃) thin films are prepared by two different chemical vapor deposition (CVD) processes: the atmospheric pressure CVD (APCVD) and the plasma enhanced CVD (PECVD). The films are analyzed by x-ray diffraction and scanning electron microscopy; their gas-sensing properties are also investigated. Experimental results show that APCVD α-Fe₂O₃ films are highly sensitive and selective to smoke while PECVD films are highly sensitive and selective to alcohol. A certain amount of quadrivalent metal in the films has an effect on their sensitivity and selectivity to gases. It is found that the films will “break down” under certain conditions.     

脉冲激光沉积法制备红外光学SiC薄膜特性研究

采用脉冲激光沉积法在锗基底制备无氢SiC薄膜,研究了激光能量对SiC薄膜显微结构、成分和红外光学性能的影响规律。利用傅里叶红外光谱仪测量了锗基底SiC薄膜样品的红外透射光谱,其在785 cm-1附近有一个强烈Si-C键特征吸收峰,并在红外波数4 000~1 300 cm-1之间具有良好的透过性。通过对透射光谱拟合计算可知:在红外波段2.5~7.7 m之间,SiC薄膜的折射率和消光系数均随着激光能量的增加而增大,折射率大约从2.15上升到2.33,激光能量从400 mJ增加到600 mJ,且当激光能量为400、500 mJ时,消光系数均在10-3量级以内,光学吸收很小。研究表明,SiC薄膜在红外2.5~7.7 m波段是一种优异的光学薄膜材料。     

WS_x薄膜的脉冲激光沉积可控制备

采用脉冲激光沉积法(PLD)在单晶硅基底上制备了WSx固体润滑薄膜。利用X射线能谱仪(EDS)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)对薄膜的成分、形貌和微观结构进行了分析,采用球盘式磨损试验机在大气(相对湿度为50%～55%)环境下评价薄膜的摩擦学特性。结果表明:薄膜中S和W的原子数分数比(简称S/W比)在1.05～3.75之间可控,摩擦系数为0.1～0.2;S/W比高于2.0时薄膜成膜质量和摩擦系数显著恶化。正交试验法得出影响薄膜S/W比的因素主次顺序分别是气压、温度、靶基距和激光通量;最优工艺参数是温度150℃、靶基距45mm、激光通量5J/cm2、气压1Pa,可获得结构致密、成分接近化学计量比的WSx薄膜。     

Atmospheric pressure chemical vapor deposition of blanket tungsten films on silicon substrates for integrated circuit applications

Atmospheric pressure chemical vapor deposition (APCVD) of tungsten films using WF₆/H₂ chemistry has been studied. A statistical design of experiments approach and a surface response methodology were used to determine the most important process parameters and to obtain the best quality film possible in the parameter range studied. It was found that the deposition rate depends strongly on WF₆ flow rate, temperature, and the interaction between hydrogen flow rate and temperature. The resistivity was found to have a strong dependence on WF₆ and H₂ flow rates and temperature. An activation energy of 0.4 eV was calculated for the reaction rate limited growth regime. Empirical equations for predicting the deposition rate and resistivity were obtained. The resistivity decreases with both increasing film thickness and grain size. The films grown in the studied process parameter range indicate that (110) is the preferred orientation for films deposited with low WF₆/H₂ flow rate ratios at all deposition temperatures (350–450°C), whereas, the (222) orientation dominates at high WF₆/H₂ flow ratios and high deposition temperatures. Also, the grain size is larger for (222) oriented films than for (110) oriented films. The results of this study suggest that high-quality, thin film tungsten can be deposited using APCVD.     

Dielectric properties of Fe-doped BaxSr1−xTiO3 thin films on polycrystalline substrates at temperatures between −35 and +85 °C

Large-area Ba_xSr_1−xTiO₃ (BSTO-x) thin films, partially Fe-doped, have been grown by pulsed laser deposition (PLD) on technically relevant polycrystalline alumina based ceramics. The capacity (dielectric constant _r) and Q-factor of planar Pt/BTO:Fe/Pt capacitors were investigated within a temperature range from −35 to +85 °C. The applied DC-bias voltages were up to 10 V and the measurement frequency was 1 kHz.Although operating in the ferroelectric state below the Curie temperature, pure BaTiO₃ (BTO) thin films showed the smallest variation of _r within the temperature range from −35 to +85 °C compared to BSTO-0.6 and BSTO-0.8. The temperature dependence of _r below the Curie temperature (ferroelectric state) seems to be smaller than above the Curie temperature (paraelectric state) for the BSTO-x system. A homogeneous tunability of the capacity of about 60% was achieved for applied electrical DC voltages resulting in electrical field strengths between 0 and 5 V/μm within the whole temperature range. The Q-factor of 2 μm thick BTO films increases with increasing DC bias voltage. Furthermore, by Fe-doping of BTO films Q-factors could be increased by a factor of three up to about 70 compared to the not doped films. In addition, the temperature dependence of capacity is considerably influenced by Fe-doping.At a microwave frequency of 30 GHz high _r values of about 1500 were measured for large-area BSTO-0.45 films at room temperature deposited directly on microwave ceramic substrates. Low values of tanδ of about 0.003 were measured for the PLD-BSTO-0.45 films which corresponds to a Q-factor of more than 300. The results show the potential of ferroelectric BTO thin films for applications as tunable electronic devices in a wide temperature range.     

Rapid thermal annealing applied to the optimization of titanium oxide arc

In this work, rapid thermal annealing (RTA) in the 400–700°C range is used to adjust simultaneously the index and thickness of titanium oxide layers in order to achieve an antireflection coating (ARC) in industrial conditions (large solar cells with a high throughput capability). The technique used for high production rate and low cost coating process is the atmospheric pressure chemical vapor deposition (APCVD) at low temperature.Titanium oxide layers are obtained from the hydrolysis of two precursors, namely the tetraisopropoxide titanate (TPT) and the titanium tetrachloride. In the first case, on silicon substrates at 150°C, we have obtained refractive indices of 1.8–1.9 with layer thicknesses in the range 70–100 nm. In the second case, at 100°C, the refractive index is 2.1–2.2 as deposited and the thickness in the same range. After RTA lasting 120 s at 700°C, the refractive index is 2.25 and the thickness is decreased by 40% with the first precursor, while with chloride, the index increases until 2.4 and the thickness is decreased by 30%. These results are discussed by means of X-ray diffraction and SIMS analysis.     

ULSI低介电常数材料制备中的CVD技术

综述了制备ULSI低介电常数材料的各种CVD技术。详细介绍了PCVD技术淀积含氟氧化硅薄膜、含氟无定型碳膜与聚酰亚胺类薄膜的工艺,简要介绍了APCVD技术淀积聚对二甲苯类有机薄膜及RTCVD技术淀积SiOF薄膜的工艺。     

Characterization of 3C-SiC thin films grown on Si surfaces patterned with various periods and depths

The effects of pattern dimension on the quality of cubic SiC thin films were investigated, grown on patterned Si substrates using the chemical vapor deposition technique. Results of various characterization techniques indicated that the quality of SiC films on the patterned substrates does not noticeably improve. It was observed from high-resolution x-ray diffraction (XRD) that SiC films on scratched surfaces (≤10-nm deep) show comparable quality to SiC on flat Si, and the quality of the SiC grown on substrates with saw-tooth patterns (∼25-nm or ∼75-nm deep) might even be lower than that of the SiC/flat-Si films.     

脉冲激光沉积AZO薄膜及其光学性质研究

给出了在氧气气氛中利用单束脉冲激光交替作用锌靶和铝靶进行掺铝氧化锌(AZO)透明导电薄膜的脉冲激光沉积(PLD)新方法,分析了该方法的特点与优点,并与利用ZnO陶瓷掺杂靶制备AZO薄膜的方法进行了对比。利用该方法分别在玻璃片和硅片上制备了AZO薄膜,用SEM观察了薄膜的表面型貌,用X射线衍射谱(XRD)研究厂薄膜的结构,最后通过透射光谱分析了制备的透明导电膜在可见光区的透射性能。实验结果表明:利用该方法能够制备出性能优越的AZO功能薄膜。     

Microstructure and electrical properties of nitrogen doped 3C–SiC thin films deposited using methyltrichlorosilane

The growth, microstructure and electrical properties of in-situ nitrogen doped 3C–SiC (111) thin films for sensor applications are presented in this paper. These thin films are deposited at a pressure of 2.5 mbar and temperature of 1040 °C on thermally oxidized Si (100) substrates from methyltrichlorosilane (MTS) precursor using a hot wall vertical low pressure chemical vapor deposition (LPCVD) reactor. Ammonia (NH₃) is used as the nitrogen doping gas. The sensor response depends on chemical composition, structure, morphology and operating temperature. The above properties are investigated for all in situ nitrogen doped (0, 9, 17 and 30 at% of nitrogen) 3C–SiC thin films using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and four probe method. The XRD patterns of the 3C–SiC thin films show a decrease in the crystallinity and intensity of the peak with increase in dopant concentration from 0 to 17 at%. AFM investigations show an improvement in the grain size of the nitrogen doped 3C–SiC thin films with increase in nitrogen concentration from 0 to 17 at%. The sheet resistance of nitrogen doped 3C–SiC thin films is measured by the four probe technique and it is found to decrease with increase in temperature in the range of 40–550 °C. The resistivity and average temperature coefficient of resistance (TCR) of doped 3C–SiC thin film deposited with 17 at% of nitrogen concentration are found to be 0.14 Ω cm and −103 ppm/°C, respectively and this can be used as a sensing material for high temperature applications.     

氮气压强对脉冲激光沉积类金刚石薄膜和红外光学特性的影响

为了研究氮气压强对脉冲激光沉积(PLD)类金刚石(DLC)薄膜和红外光学特性的影响,在脉冲激光沉积类金刚石薄膜的实验过程中,把沉积腔抽真空到10-5Pa,再在沉积腔中分别充入10-3、10-2和10-1Pa的氮气来沉积类金刚石薄膜。用拉曼光谱仪和X射线光电子能谱仪(XPS)对类金刚石薄膜的微结构与组成进行检测分析;用原子力显微镜(AFM)对薄膜的表面形貌进行检测分析;用傅里叶变换红外光谱仪(FTIR)对类金刚石薄膜的红外光透射谱进行检测分析。实验结果表明,沉积腔中的氮气压强从10-3Pa增加到10-1Pa时,类金刚石薄膜中sp3键含量增加;C-O和C=O含量减少;石墨晶粒尺寸减小;薄膜表面粗糙度显著增大。与此同时,氮气压强增加还导致类金刚石薄膜对红外光的增透作用减弱、增透范围变窄。     

Bismuth doped ZnSe films fabricated on silicon substrates by pulsed laser deposition

The preparation of bismuth doped ZnSe films on silicon (1 0 0) by pulsed laser deposition (PLD) is reported. Bismuth was used as a p-type dopant source material for ZnSe. The stable p-type films with hole carrier concentration of about 10¹⁶–10¹⁸ cm^?3 were obtained. By scanning electron microscopy (SEM) and X-ray diffraction (XRD), it was found that the ambient pressure during film deposition has much to do with the morphology and crystallinity of the as-deposited products. The presence of Bi in the Bi-doped ZnSe films was confirmed by the X-ray photoelectron spectroscopy (XPS) and the possibility of a Bi_Zn–2V_Zn complex forming a shallow acceptor level was discussed.     

铝膜沉积温度对铝诱导结晶化多晶硅薄膜性能的影响

以超白玻璃为衬底,采用热丝化学气相沉积法沉积初始非晶硅膜,经自然氧化形成二氧化硅层,最后利用磁控溅射 法在不同衬底温度下沉积铝膜,制备了glass/Si/SiO/Al叠层结构并对其进行铝诱导晶化形成多晶硅薄膜.用X射线衍射,光学显微镜和拉曼光谱对样品进行了分析.结果表明,铝诱导晶化制备的多晶硅薄膜的晶粒大小随着铝膜沉积...     

外延生长6H-SiC/Si薄膜的微结构研究

采用 Si H4 -C3H8-H2 气体反应体系 ,通过 APCVD工艺在 Si(1 0 0 )衬底上进行 Si C薄膜生长时 ,严格控制缓冲层生长的工艺条件 ,即 1 3 0 0°C碳化温度较高的 C3H8饱和浓度 ,可以获得结晶质量良好的 6H-Si C单晶外延层。利用 SEM、X射线衍射能谱 (XRD)及光致发光谱 (PL)分析了薄膜微结构并讨论了其微观机制     

Characterization of rare earth oxides based MOSFET gate stacks prepared by metal-organic chemical vapour deposition

We have prepared rare earth oxides based MOSFET gate stacks using metal-organic chemical vapour deposition, MOCVD. Gd₂O₃, La₂O₃, Nd₂O₃ and Pr₆O₁₁ films with thickness 3–20 nm were deposited on silicon substrate at 500 °C. The films were characterized by X-ray diffraction, X-ray reflectivity, transmission electron microscopy and X-ray photoelectron spectroscopy. As a next step, Ru films were grown on the dielectric films at 300 °C as a gate electrode. Electrical characterization of the MOS structures was performed by capacitance–voltage measurements. The structures annealed at 430 °C in forming gas (90% N₂+10% H₂) exhibited dielectric constant ranging from 12 to 14. Typically, the films showed high values of fixed oxide charge density, . Fixed oxide charges can be decreased by post-deposition annealing in forming gas and in oxygen.