The effects of substrate bias,substrate temperature,and pulse frequency on the microstructures of chromium nitride coatings deposited by pulsed direct current reactive magnetron sputtering

Recently, great attention has been devoted to the pulsed direct current (DC) reactive magnetron sputtering technique, due to its ability to reduce arcing and target poisoning, and its capability of producing insulating thin films. In this study, chromium nitride (CrN) coatings were deposited by the bipolar symmetric pulsed DC magnetron reactive sputtering process at different pulse frequency, substrate bias voltage, and the substrate temperature. It was observed that the texture of CrN changed from (111) to (200) as substrate temperature increased to 300°C as deposited at 2 kHz without substrate bias. With increasing pulsing bias and pulse frequency of target, predominated (200) orientation of CrN film was shown due to the ion bombardment/channeling effect to preferentially sputter those unaligned planes. For the CrN coatings deposited with pulsed biasing, the grain size decreased with increasing pulse frequency and substrate bias, whereas the surface roughness showed a reverse trend. The deposition rate of the CrN films decreased with increasing pulse frequency. It was concluded that the pulse frequency, substrate bias, and substrate temperature played important role in the texture, microstructure, and surface roughness of the CrN coatings deposited by the pulsed DC magnetron sputtering process.     

Texture enhancement of Al films on Ti underlayers by radio-frequency bias sputtering

The influence of sputtering pressure and radio-frequency (RF) bias power on the texture of Al/Ti thin films has been investigated. The Al/Ti thin films were deposited sequentially onto thermally oxidized Si wafers in a direct-current (DC) magnetron system. The RF bias was applied during Ti deposition. The texture of Al thin films was quantified by θ–2θ scans and rocking curves of x-ray diffraction (XRD). The Al thin films deposited on bias-sputtered Ti underlayers showed an epitaxial growth and strong (111) texture. The Al (111) texture improved with decreasing sputtering pressure and increasing RF-bias power. The Al/Ti texture was also enhanced when the SiO₂/Si substrate surface was RF plasma cleaned prior to Ti deposition. The Al (111) texture was closely related to Ti (0002) texture. The mechanism of Ti-texture improvement by applying bias sputtering was explained based on the ion-bombardment effect.     

Texture and electromigration lifetime improvements in layered Al-alloy metallization with underlying Ti by controlling water adsorption on SiO2 substrates

The effect of residual gas constituents and substrate temperature during Ti sputtering on the texture of TiN/Ti films deposited on SiO₂/Si substrates has been investigated. The Ti(002) and TiN(111) preferred texture of the films deposited at 350°C was found to be improved drastically by increasing the H₂O partial pressure from 1×10⁻⁹ to 3×10⁻⁸ Torr. Both of the Ti(002) and TiN(111) textures showed a similar H₂O partial pressure and substrate temperature dependence because of the epitaxial transfer between these planes. The improved Ti(002) texture was attributed to the self-assembly of Ti atoms on the SiO₂ surface, which had a low surface free energy due to the formation of surface OH groups. Two kinds of layered Al-alloy interconnects, AlSiCu/Ti/TiN/Ti and AlCu/TiN/Ti, were fabricated with the highly textured TiN/Ti film, and their Al(111) texture and electromigration lifetime were then evaluated. It was confirmed that both of the interconnects have strong Al(111) texture and longer EM lifetimes.     

不同N2气流量比反应溅射TiN薄膜的表面形貌分形特征

采用反应磁控溅射工艺通过改变N<,2气流量比在Si衬底上沉积300nm厚TiN薄膜.用原子力显微镜(AFM)观察薄膜表面形貌,并根据分形理论予以定量表征.结果表明:TiN薄膜的溅射模式与分形维数D<,f>值的演化存在相关性.当N<,2气流量比由O.0%增加至4.0%时,TiN薄膜的溅射方式属于金属模式,D<,f>保持不变;当N<,2气流量比继续增加至10.0%时,薄膜溅射方式转变为过渡模式,此时D<,f>急剧减小;而当N<,2气流量比超过10.0%以后,薄膜溅射模式改变为氮化物模式,相应的D<,f>轻微增加.     

钯膜上CVD法制备碳纳米管薄膜的研究

采用化学气相沉积法,以乙炔为碳源,在各种钯膜上制备了碳纳米管薄膜。通过电子显微镜观察了碳管薄膜和钯膜的表面形貌。结果表明,在真空气氛下磁控溅射的钯膜上无法生长碳纳米管。对溅射的钯膜进行大气气氛下的退火处理,则可生长出稀疏的碳纳米管团聚颗粒。采用在氧气气氛下磁控溅射的钯膜作为催化剂,则可显著提高碳管的生长密度和纯度,从而获得致密均匀的碳纳米管薄膜。     

Sputter deposition of phosphors for electroluminescent flat panel displays

Thin film electroluminescent (TFEL) phosphors for flat panel displays have been produced by several different growth methods including atomic layer epitaxy, chemical vapor deposition, and sputter deposition. There is a great deal of interest in sputter deposition due to the extensive knowledge base and equipment from other existing thin film manufacturing. However, deposition of sulfide-based TFEL phosphors by conventional radio frequency magnetron sputtering has proven to be difficult due to the formation of negative sulfur ions near the target which are accelerated to the growing film by the self-bias developed on the target. This negative-ion resputtering can result in amorphization or re-sputtering of the phosphor films. In severe cases, a net sputtering of the substrate can result. In order to remedy this negative ion resputtering problem, modifications of the magnetron geometry and ion-beam sputtering have been evaluated for production of Ca_xSr_1−xGa₂S₄:Ce and SrS:Ce TFEL phosphors. Sputter deposited TFEL films also typically require a postdeposition anneal which adds to expense and can cause other problems for the flat panel display. Ion-beam assist during deposition of undoped ZnS was studied as a method to induce surface-atom mobility and a more crystalline as-deposited film for use in monochrome TFEL displays.     

Inductively coupled plasma assisted physical vapor deposition of titanium nitride coatings

Beneficial effects of increased low energy ion bombardment during physical vapor deposition of ceramic thin films and coatings have been amply documented recently. We have constructed a small laboratory scale high density inductively coupled plasma (ICP) assisted magnetron sputtering system. Such a system offers higher plasma densities as compared to conventional magnetron sputtering. We describe the synthesis of titanium nitride coatings at relatively low temperatures by ICP assisted reactive magnetron sputter deposition.     

Analysis of Ti–Si–N diffusion barrier films obtained by r.f. magnetron sputtering

Thin films of Ti–Si–N are deposited by r.f. magnetron sputtering in a Ar/N₂ gas mixture. The magnetron discharge is operated at 10 mTorr with 5 and 10% N₂ in the gas mixture and r.f. powers ranging from 100 to 200 W. The composition and electrical resistivity of the thin films were determined by energy dispersive X-ray spectroscopy and the four-point probe method, respectively. The structure of the films was determined by high-resolution transmission electron microscopy. The Ti–Si–N films were either amorphous or contained cubic TiN nanosized grains in an amorphous phase. The diffusion barrier properties of 10-nm thick film between Cu and Si were studied from 500 to 700°C. The highest failure temperature of 650°C was obtained for Ti_37.5 Si₂₇ N_35.5 which. contains 4-nm TiN crystallites in an amorphous phase.     

Characterizations of high resistivity TiNxOy thin films for applications in thin film resistors

We report about developing high resistivity thin film resistors using titanium oxy-nitride. Titanium nitride films of different thicknesses ranging from 50 to 300 nm were deposited on SiO₂/Si substrates using the reactive magnetron sputtering method. After deposition, these films were annealed in the air ambient. The structural and electrical properties of the films were examined as a function of annealing temperature. The samples with various thicknesses show TiN(1 1 1) phase. The sheet resistance increases from 150 up to 420 Ω/□ when the film thickness decreases from 300 to 50 nm. Temperature coefficience of resistance (TCR) of the films significantly decreased with decreasing the film thickness. The TCR of 50-nm thick film is quite low, about 49 ppm/K.     

Investigation of RF sputtered PSG films for MEMS and semiconductor devices

In this work, we report the preparation of phospho-silicate-glass (PSG) films using RF magnetron sputtering process and its application as a sacrificial layer in surface micromachining technology. For this purpose, a 76 mm diameter target of phosphorus-doped silicon dioxide was prepared by conventional solid-state reaction route using P₂O₅ and SiO₂ powders. The PSG films were deposited in a RF (13.56 MHz) magnetron sputtering system at 200-300 W RF power, 10-20 mTorr pressure and 45 mm target-to-substrate spacing without external substrate heating. To confirm the presence of phosphorus in the deposited films, hot-probe test and sheet resistance measurements were performed on silicon wafers following deposition of PSG film and a drive-in step. As a final confirmatory test, a p-n diode was fabricated in a p-type Si wafer using the deposited film as a source of phosphorus diffusion. The phosphorus concentration in the target and the deposited film were analyzed using energy dispersive X-rays (EDAX) tool. The etch rate of the PSG film in buffered HF was measured to be about 30 times higher as compared to that of thermally grown SiO₂ films. The application of RF sputtered PSG film as sacrificial layer in surface micromachining technology has been explored. To demonstrate the compatibility with MEMS process, micro-cantilevers and micro-bridges of silicon nitride were fabricated using RF sputtered PSG as a sacrificial layer in surface micromachining. It is envisaged that the lower deposition temperature in RF sputtering (<150 °C) compared to CVD process for PSG film preparation is advantageous, particularly for making MEMS on temperature sensitive substrates.     

The behaviour of ZrB x (0 ≤x ≤ 2) thin films deposited on si substrate as a function of annealing treatment

Thin films of ZrB _x (0 ≤x ≤ 2) have been deposited on Si substrates by dc magnetron sputtering. The effects of annealing the films have been studied as a function of film composition by sheet resistance measurements, supplemented by Rutherford backscat-tering, Auger electron spectroscopy and x-ray diffraction. Significant departures of film composition from stoichiometric ZrB₂ can result in an accompanying Zr-Si reaction cou-ple during annealing treatment which influences the overall film behaviour. These ef-fects are discussed with respect to the possible usefulness of ZrB₂ films for VLSI metalli-sation and barrier layer applications.     

Simulation and experimental analysis of planarization of refractory metals using a multi-step sputter/sputter etch process

In this paper, we will present both experimental and simulated results showing the use of successive sputter deposition and sputter etching of refractory metal films deposited into trenches. A layer of 0.5 μm thick film was deposited using a magnetron sputtering source and then etched back to 0.25 μm using radio frequency sputter etching. A multilayer film was built up by repetition of this process. Both the step coverage and planarization of the films improved relative to one-step sputter deposited films. The SIMulation by BAllistic Deposition (SIMBAD) simulation program was extended to allow for the modeling of multilayer films. SIMBAD was successful in modeling the sputter/sputter etch process and accurately modeled the microstructure of the films deposited. Particular emphasis in the paper is put on evaluating the performance of SIMBAD in predicting the microstructure of the film. This microstructure was found to be substantially altered if the vacuum system was vented between layer deposition.     

工艺条件对柔性衬底ITO薄膜光电性能的影响

采用直流磁控溅射法在柔性衬底上镀制ITO透明导电薄膜,全面研究了薄膜厚度、氧气流量、溅射速率、溅射气压和镀膜温度等工艺条件对ITO薄膜光电性能的影响。结果表明,当膜厚大于80nm、氧氩体积比为1∶40、溅射速率为5nm/min、溅射气压在0.5Pa左右、镀膜温度为80～160℃时,ITO薄膜的光电性能较好,其电阻率小于5×10–4?·cm、可见光透光率大于80%。     

Standard and self-sustained magnetron sputtering deposited Cu films investigated by means of AFM and XRD

The goal of conducted investigations was to study microstructure and surface morphology of copper thin films deposited during standard (with argon) and self-sustained (without argon presence) magnetron sputtering deposition processes. Different types of magnetron source powering were used: direct current (DC), medium frequency (MF), pulsed-DC. The investigated copper films were deposited by means of balanced magnetron sputtering source on Si (1 1 1) substrates. The results of investigations showed that the average size of the copper crystallites of all samples were equal to dozens of nanometre. However, the self-sustained sputtering deposition processes, in comparison to the standard ones, resulted in smoother film surface.     

直流磁控溅射制备非晶硅薄膜的研究

非晶硅薄膜（a-Si）是目前重要的光敏材料,在很多领域得到广泛应用。直流磁控溅射具有工艺简单．沉积温度低等优点,是制备薄膜的一种重要技术。采用直流磁控溅射工艺在玻璃基板上沉积薄膜,并对样品进行了退火处理。研究了沉积速率与溅射功率的关系。结果表明薄膜的沉积速率与溅射功率近似有线性关系。利用X射线衍射（XRD）对薄膜进行了分析鉴定,结果表明溅射的薄膜是非晶硅薄膜。利用扫描电子显微镜（SEM）对非晶硅薄膜的表面形貌进行了观察和分析,与X射线衍射测试的结果一致。所以．利用直流磁控溅射工艺能在常温下能快速制备出良好的非晶硅薄膜。     

TiN薄膜表面形貌的分形表征及其演化特征

用反应磁控溅射方法在Si基片上沉积TiN膜,用原子力显微镜(ARM)观察薄膜表面形貌.比较研究了尺码法、盒计数法、功率谱密度法与高度-高度相关函数法计算的表面形貌分形维数Df结果,并研究了TiN膜表面形貌的演化特征.结果表明,功率谱密度法与高度-高度相关函数法计算的Df值与AFM观测尺度不相关,具有较好的稳定性,随着膜厚h增加,薄膜分形维数Df先减小再增加,这是由生长初期基片表面影响与生长后期的晶粒长大所导致的.     

Photo CVD system for silicon nitride film

An ultraviolet light excitation photo CVD system for silicon nitride film deposition, in which the use of mercury photo-sensitizer and the undesirable wall deposition onto the optical window inside are eliminated, has been developed. The elimination of the use of mercury sensitizer is achieved by employing direct photolysis of SiH₄/NH₃ gas mixture, using 185 nm light emitted from a low pressure mercury lamp. The wall deposition prevention is achieved by inserting an optically transparent “separator plate” with a number of through-holes on its plane area underneath the optical window and by draining inert gas into the reaction chamber through this “separator plate.” With this system, silicon nitride films have been deposited without marked degradation of deposition rate, keeping a reasonable deposition rate of about 40 A/minute. The inert gas used for wall deposition prevention has no influence on the properties of deposited films.     

Lambertian matched absorption enhancement in PECVD poly‐Si thin film on aluminum induced textured glass superstrates for solar cell applications

This paper examines the effectiveness of a range of aluminum induced textured (AIT) glass topographies at enhancing light absorption in silicon thin film diode structures deposited on the textured glass side, operating in the superstrate configuration. The aluminum layer used to produce the AIT can be deposited either by thermal evaporation or magnetron sputtering. Varying AIT process parameters produces a wide range of feature roughness and uniformity, providing scope to optimize texture effectiveness and process repeatability. We report strong correlation between the degree of absorption enhancement from these textures and both dark field microscope images of the AIT glass and reduction of the interference envelope in spectral reflectance of the deposited silicon films. Our findings corroborate earlier modeling work based on ray tracing, which predicted that the best enhancement occurs when the feature size is close to the film thickness. In this paper we investigate AIT samples in the 1 – 3 µm film thickness range, some of which trap light in silicon as strongly as at the Lambertian limit. Copyright © 2010 John Wiley & Sons, Ltd.     

Ti-O Direct-Current-Sintered Bodies and Their Use for Sputter Deposition of TiO Thin Films: Fabrication and Characterization

Ti-50at.%O and Ti-40at.%O sintered bodies were fabricated by direct-current sintering using Ti and TiO₂ powders as starting materials. Their microstructures were investigated by x-ray diffraction and optical microscopy. Ti-O thin films were deposited on glass substrates by radiofrequency (RF) magnetron sputtering using a Ti-50at.%O or Ti-40at.%O sintered body as a sputtering target. A crystalline TiO thin film was obtained using a Ti-40at.%O sputtering target, while an amorphous or Ti₆O₁₁ thin film was obtained using a Ti-50at.%O sputtering target. The electric resistivity of the TiO thin films was 450 μΩ cm to 1000 μΩ cm depending on their thickness.     

Properties of magnetron sputtered hydrogenated amorphous silicon

Hydrogen concentrations and bonding configurations were studied in hydrogenated amorphous silicon (a-Si:H) films deposited at 50‡C using the magnetron mode of sputtering with partial hydrogen concentrations between 0 and 90 percent in flowing argon. Hydrogen content within the films was determined from nuclear reaction analysis, and the chemical bonding of hydrogen was determined from infrared absorption of as-deposited, thermally annealed, and ion-bombarded films. Hydrogen/silicon ratios in the films increase to a maximum of 0.31 with increasing hydrogen in the deposition system. Ion backscattering shows ∼ 6 at.% argon trapped in the films, but no oxygen was detected by either ion backscattering or by sputter-Auger analysis. The wag and bend modes for Si-H in the films are typical of sputter-deposited a-Si:H; however, the stretch mode region is atypical with absorption near 2000 cm^−l dominating even for H/Si ratio of 0.27. From results of thermal annealing and post-deposition ion bombardment, it is concluded that argon ion bombardment during deposition produces enhanced absorption near 2000 cm^-1 in these a-Si:H films deposited by magnetron sputtering. This work was sponsored in part by the U. S. Department of Energy, under Contract DE-AC04-76-DP00789 and the U. S. Army Research Office, Contract DAA29-79-C-0026. U. S. Department of Energy facility.