高介电常数Ta/Al_2O_3复合膜的制备及性能研究

首次在溴的丙酮溶液中,以钽为阳极,氧化铝为阴极,通过直流电沉积方法制备了Ta/Al_2O_3复合膜。借助LCR数字电桥、SEM、EDS等测试手段对Ta/Al_2O_3复合膜的介电性能及微观结构进行了分析与表征。研究表明:Ta/Al_2O_3复合氧化膜的表面沉积了质量分数为41.77%的钽。与普通铝阳极(Al_2O_3)氧化膜相比,复合氧化膜的电容提高了50%以上,这主要归因于介电常数较高的钽在复合氧化膜表面的沉积。     

铜互连中SiCOF/a-C:F双层低介电常数薄膜的制备和表征

用等离子体化学气相淀积系统制备了一种新颖的SiCOF/a-C:F双层低介电常数介质薄膜,并用红外光谱表征了该薄膜的化学结构.通过测量介质的折射率发现该薄膜长时间暴露在空气中,其光频介电常数几乎不变.然而,随退火温度的增加,其光频介电常数则会减小.基于实验结果讨论了几种可能的机理.二次离子质谱分析表明在Al/a-C:F/Si结构中F和C很容易扩散到Al中,但在Al/SiCOF/a-C:F/Si结构中,则没有发现C的扩散,说明SiCOF充当了C扩散的阻挡层.分析还发现在SiCOF和a-C:F之间没有明显的界面层.     

基于高温制备的氧化钙镁复合薄膜光电特性研究

采用电子束蒸镀工艺制备氧化钙掺杂氧化镁复合介质保护膜并深入分析了制备温度对该复合保护膜透过率及二次电子发射效率的影响。实验表明,高温制备能够使复合薄膜表面形貌更为致密,结晶粒径增加,薄膜的透过率和发光效率提高。当制备温度为300℃时,复合薄膜的形貌更为致密平整,裕度从25V增加到32V,发光效率从1.70lm/W提高到1.91lm/W,提高了12.35%。     

Investigations on electrical characteristics and reliability properties of MOS capacitors using HfAlOx on n-GaAs substrates

Radio frequency sputtering system is employed to fabricate metal oxide semiconductor (MOS) capacitors using an ultra-thin layer of HfAlO_x dielectric deposited on n-GaAs substrates with and without a Si interface control layer incorporated in between the dielectric and the semiconductor. Measurements are performed to obtain capacitance voltage (C–V) and current voltage (I–V) characteristics for GaAs/Si/HfAlO_x and GaAs/HfAlO_x capacitors under different constant voltage and constant current stress conditions. The variation of different electrical parameters such as change in interface trap density, hysteresis voltage with various values of constant voltage stress and the dependence of flat band voltage, fractional change in gate leakage current density, etc. with stress time are extracted from the C–V and I–V data for capacitors with and without a Si interlayer. Further the trap charge density and the movement of trap centroid are investigated for various injected influences. The dielectric breakdown and reliability properties of the dielectric films are studied using constant voltage stressing. A high time-dependent dielectric breakdown (TDDB, t_bd ? 1350 s) is observed for HfAlO_x gate dielectric with a silicon inter-layer under the high constant voltage stress at 8 V. Compared to capacitors without a Si interlayer, MOS capacitors with a Si interlayer exhibit improved electrical and breakdown characteristics, and excellent interface and reliability properties.     

氮化铝-铝复合封装基板的制备

采用磁控溅射法在阳极氧化预处理过的铝板上沉积氮化铝薄膜,制备氮化铝-铝复合基板。制备的氮化铝为非晶态,抗电强度超过700 V/μm,阳极氧化铝抗电强度达75 V/μm。当阳极氧化铝膜厚约10μm、氮化铝膜约1μm时,制备的复合封装基板击穿电压超过1350 V,绝缘电阻率1.7×106 MΩ·cm,氮化铝与铝板的结合强度超过8 MPa;阳极氧化铝膜作为缓冲层有效缓解了氮化铝与铝热膨胀系数失配的问题,在260℃热冲击下,铝板未发生形变,氮化铝膜未破裂,电学性能无明显变化。氮化铝与阳极氧化膜的可见光高透性保持了镜面抛光金属铝的高反射率,当该复合基板应用于LED芯片COB封装时,有助于提高封装光效。     

Effects of ${hbox{CNT/BaTiO}}_{3}$ Composite Particles Prepared by Mechanical Process on Dielectric Properties of Epoxy Hybrid Films

A new type of composite filler mechanically treated with multi-walled carbon nanotubes (MWNTs) and (BT) particles was prepared to produce higher dielectric properties in the composite. The hybrid film fabricated by incorporating these composite fillers in an epoxy matrix had a high dielectric constant and similar dielectric loss as compared to the composite which contained neat BT particles. The dielectric properties of these hybrid films were found to be dependent on both the content of MWNTs and mechanical processing time. Results suggest that this novel hybrid film composed of the composite filler and the epoxy matrix can be used for embedded capacitor material.     

An All‐Solid‐State Flexible Piezoelectric High‐k Film Functioning as Both a Generator and In Situ Storage Unit

An all‐solid‐state flexible generator–capacitor polymer composite film converts low‐frequency biomechanical energy into stored electric energy. This design, which combines the functionality of a generator with a capacitor, is realized by employing poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) in the simultaneous dual role of piezoelectric generator and polymer matrices of the flexible capacitor. Proper surface modification of the reduced graphene oxide (rGO) fillers in the polymeric matrices is indispensable in achieving the superior energy storage performance of the composite film. The heightened dielectric performance stems from enhanced compatibility of the rGO fillers and PVDF‐HFP matrices, and a microcapacitor model properly explains the dielectric behaviors. A device that is easily fabricated using our film allows timely decoupled motion energy harvest and output of the motion‐generated electricity. This report opens new design possibilities in the fields of motion sensors, information storage and high‐voltage output by accumulating low‐frequency random biological motions.     

低介电常数含氟氧化硅薄膜的红外光谱分析

用等离子体化学气相淀积 (PECVD)制备了含氟氧化硅薄膜 (Si OF薄膜 )。通过傅里叶变换红外光谱 (FTIR)分析 ,研究了氟掺入后薄膜结构的变化 ,并进一步讨论了氟对薄膜介电常数及吸水性的影响。研究表明氟掺入后改变了 Si- O键上的电荷分布 ,降低了薄膜中 Si- O键的极性 ,导致 Si- O键伸缩振动吸收峰发生蓝移。同时氟的掺入抑制了强极性 Si- OH键的形成。这些变化有利于薄膜中离子极化和偶极子转向极化的降低 ,因而使薄膜介电常数减小。对 Si- F吸收峰的高斯拟合表明 ,在氟含量较高时 ,薄膜中掺入的氟一部分会以 Si F2 结构存在。由于 Si F2 结构稳定性较差 ,易与水汽发生作用 ,因而高氟掺杂的 Si OF薄膜易吸水 ,并使薄膜性能变差     

阳极氧化膜形成液中的氯离子检测

通过对阳极氧化膜形成液现有的检测方法分析,针对介电用阳极氧化膜形成中形成液的形成能力无法真实检测的问题,利用纯铝样品作为传感探头,在不同浓度的形成液和含有腐蚀性成分的电解液中,测试样品的电流变化情况,确定了介电用阳极氧化膜形成液中的氯离子检测方法。     

Investigation of hole-tunneling current through ultrathinoxynitride/oxide stack gate dielectrics in p-MOSFETs

The systematic investigation of hole tunneling current through ultrathin oxide, oxynitride, oxynitride/oxide (N/O) and oxide/oxynitride/oxide (ONO) gate dielectrics in p-MOSFETs using a physical model is reported for the first time. The validity of the model is corroborated by the good agreement between the simulated and experimental results. Under typical inversion biases (|VG|<2 V), hole tunneling current is lower through oxynitride and oxynitride/oxide with about 33 at.% N than through pure oxide and nitride gate dielectrics. This is attributed to the competitive effects of the increase in the dielectric constant, and hence dielectric thickness, and decrease in the hole barrier height at the dielectric/Si interface with increasing with N concentration for a given electrical oxide thickness (EOT). For a N/O stack film with the same N concentration in the oxynitride, the hole tunneling current decreases monotonically with oxynitride thickness under the typical inversion biases. For minimum gate leakage current and maintaining an acceptable dielectric/Si interfacial quality, an N/O stack structure consisting of an oxynitride layer with 33 at.% N and a 3 Å oxide layer is proposed. For a p-MOSFET at an operating voltage of -0.9 V, which is applicable to the 0.7 μm technology node, this structure could be scaled to EOT=12 Å if the maximum allowed gate leakage current is 1 A/cm² and EOT=9 Å if the maximum allowed gate leakage current is 100 A/cm²     

Thin RF sputtered and thermal Ta2O5 on Si for high density DRAM application

Tantalum pentoxide thin films on Si prepared by two conventional for modern microelectronics methods (RF sputtering of Ta in Ar + O₂ mixture and thermal oxidation of tantalum layer on Si) have been investigated with respect to their dielectric, structural and electric properties. It has been found that the formation of ultra thin SiO₂ film at the interface with Si, during fabrication implementing the methods used, is unavoidable as both, X-ray photoelectron spectroscopy and electrical measurements, have indicated. The initial films (as-deposited and as-grown) are not perfect and contain suboxides of tantalum and silicon which act as electrical active centers in the form of oxide charges and interface states. Conditions which guarantee obtaining high quality tantalum oxide with dielectric constant of 32–37 and leakage current density less than 10⁻⁷ A/cm² at 1.5 V applied voltage (Ta₂O₅ thickness equivalent to about 3.5 nm of SiO₂) have been established. These specifications make the layers obtained suitable alternative to SiO₂ for high density DRAM application.     

Transients during pre-breakdown and hard breakdown of thin gate oxides in metal–SiO2–Si capacitors

Time–resolved electrical measurements show transient phenomena occurring during degradation and intrinsic dielectric breakdown of gate oxide layers under constant voltage Fowler–Nordheim stress. We have studied such transients in metal/oxide/semiconductor (MOS) capacitors with an n⁺ poly-crystalline Si/SiO₂/n-type Si stack and with oxide thickness between 35 and 5.6 nm. The data adds new information concerning the intrinsic breakdown mechanism and these are shown and discussed together with the adopted measurement techniques.     

Electrical conduction and dielectric breakdown in aluminum oxideinsulators on silicon

Leakage currents and dielectric breakdown were studied in MIS capacitors of metal-aluminum oxide-silicon. The aluminum oxide was produced by thermally oxidizing AlN at 800-1160°C under dry O₂ conditions. The AlN films were deposited by RF magnetron sputtering on p-type Si (100) substrates. Thermal oxidation produced Al ₂O₃ with a thickness and structure that depended on the process time and temperature. The MIS capacitors exhibited the charge regimes of accumulation, depletion, and inversion on the Si semiconductor surface. The best electrical properties were obtained when all of the AlN was fully oxidized to Al₂O₃ with no residual AlN. The MIS flatband voltage was near 0 V, the net oxide trapped charge density, Q_0x, was less than 10¹¹ cm ^-2, and the interface trap density, D_it, was less than 10¹¹ cm^-2 eV^-1, At an oxide electric field of 0.3 MV/cm, the leakage current density was less than 10^-7 A cm^-2, with a resistivity greater than 10 ¹² Ω-cm. The critical field for dielectric breakdown ranged from 4 to 5 MV/cm. The temperature dependence of the current versus electric field indicated that the conduction mechanism was Frenkel-Poole emission, which has the property that higher temperatures reduce the current. This may be important for the reliability of circuits operating under extreme conditions. The dielectric constant ranged from 3 to 9. The excellent electronic quality of aluminum oxide may be attractive for field effect transistor applications     

铝的结晶复合阳极氧化膜Ⅰ．水合氧化膜存在下的阳极氧化膜的形成

铝箔先与热水反应，再进行阳极氧化，可形成结晶复合阳极氧化膜。介绍这种膜的形成机理以及膜的结构。这种膜适用于制造中、高压铝电解电容器     

包裹A1_2O_3对BaTiO_3基陶瓷性能的影响

采用固相法制备掺杂有稀土元素Nd和Y的BaTiO3基陶瓷粉体,在该粉体表面包裹A12O3。研究了包裹A12O3对BaTiO3基陶瓷的微观结构、微观形貌、介电性能、击穿电压和介电非线性的影响。结果表明:包裹A12O3后,BaTiO3基陶瓷的相对介电常数达到4000,绝缘电阻率达到1011?.cm,耐压提高到20×103V/mm,介电非线性得到改善,有望在储能领域中得到应用。     

Mobility enhancement in TaN metal-gate MOSFETs using tantalum incorporated HfO/sub 2/ gate dielectric

TaN metal-gate nMOSFETs using HfTaO gate dielectrics have been investigated for the first time. Compared to pure HfO/sub 2/, a reduction of one order of magnitude in interface state density (D/sub it/) was observed in HfTaO film. This may be attributed to a high atomic percentage of Si-O bonds in the interfacial layer between HfTaO and Si. It also suggests a chemical similarity of the HfTaO-Si interface to the high-quality SiO/sub 2/-Si interface. In addition, a charge trapping-induced threshold voltage (V/sub th/) shift in HfTaO film with constant voltage stress was 20 times lower than that of HfO/sub 2/. This indicates that the HfTaO film has fewer charged traps compared to HfO/sub 2/ film. The electron mobility in nMOSFETs with HfO/sub 2/ gate dielectric was significantly enhanced by incorporating Ta.     

氧化鑭薄膜閘極結構與電性並應用在砷化鎵高速場效應電晶體研製

This paper investigates the feasibility of using a lanthanum oxide thin film （La2O3） with a high dielectric constant as a gate dielectric on GaAs pHEMTs to reduce gate leakage current and improve the gate to drain breakdown voltage relative to the conventional GaAs pHEMT. An E/D mode pHEMT in a single chip was realized by selecting the appropriate La2O3 thickness. The thin La2O3 film was characterized： its chemical composition and crystalline structure were determined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. La2O3 exhibited good thermal stability after post-deposition annealing at 200, 400 and 600℃ because of its high binding-energy （835.6 eV）. Experimental results clearly demonstrated that the La2O3 thin film was thermally stable. The DC and RF characteristics of Pt/La2O3/Ti/Au gate and conventional Pt/Ti/Au gate pHEMTs were examined. The measurements indicated that the transistor with the Pt/La2O3/Ti/Au gate had a higher breakdown voltage and lower gate leakage current. Accordingly, the La2O3 thin film is a potential high-k material for use as a gate dielectric to improve electrical performance and the thermal effect in high-power applications.     

Performance Improvement of Ultralow Temperature Polycrystalline Silicon TFT on Plastic Substrate by Plasma Oxidation of Polycrystalline Si Surface

The thin-film transistor (TFT) performances were enhanced and stabilized by the plasma oxidation of the polycrystalline Si surface prior to the plasma enhanced atomic layer deposition of an Al₂O₃ gate dielectric film. The authors attribute this improvement to the formation of a high-quality oxide interface layer between the gate dielectric film and the poly-Si film. The interface oxide has a predominant effect on the TFT's characteristics and is regulated by the plasma oxidation temperature and the gap distance between the electrode and polycrystalline Si surface     

Formation of aluminum oxide films from aluminum hexafluoroacetylacetonate at 350–450° c

A study of the thermally activated decomposition of Al(hfa)₃ (aluminum hexafluoroacetylacetonate) from the gas phase to form Al₂O₃ on silicon substrates is reported. The decomposition process was carried out in an open tube atmospheric pressure reactor in either argon or oxygen/argon mixtures in the temperature range, 350–450° C. The chemical vapor deposition process resulted in the formation of aluminum oxide films in all instances. The dielectric strength of Al/Al₂O₃/Si capacitors which received a post-metal anneal, but did not receive a high temperature annealing treatment, with aluminum oxide films prepared from Al(hfa)₃ in argon, was found to be in the range 2–6 MV/cm. The difference between the flatband voltage of the MOS structures and the metal-silicon work function difference was positive, indicative of a net negative oxide charge with a density of approximately 3 × 10¹¹ – 3 × 10¹² cm^-2, assuming the charge is located at the oxide-silicon interface. Decomposition of Al(hfa)₃ was also carried out in oxygen/argon mixtures with the oxygen concentration in the range 10–60 vol %. This process led to the deposition of aluminum oxide films with breakdown fields in the range 8–9 MV/cm. However, the flatband voltages of the Al/Al₂O₃/Si capacitors were even more positive than those obtained with Al₂O₃ formed in pure argon. High temperature (800–1000° C) oxygen or nitrogen annealing treatments of alumina films deposited in either argon or oxygen/argon mixtures were evaluated from the point of view of their influence on the oxide film properties. In particular, an annealing process in oxygen at 1000° C for 15 min was found to result in a reduction of the net negative oxide charge, and an improvement of the dielectric strength of films deposited in argon. Films formed in oxygen/argon mixtures did not change appreciably following oxygen annealing, as far as breakdown fields are concerned, but the oxide net negative charge was reduced. As in an earlier study by the authors, of copper film deposition from Cu(hfa)₂, it was found that essentially carbon free films could be obtained under appropriate conditions.     

高比容铝阳极箔复合氧化膜的研究进展及前景

简述了铝电解电容器用高比容阳极箔复合氧化膜的国内外研究现状,介绍了复合氧化膜的制备方法,着重阐述了其中最常用的溶胶-凝胶法、水解沉积法以及电化学沉积法的发展过程和性质特点,分析了国产TiO2-Al2O3复合膜电极箔的性能,跟进口箔相比,复合膜电极箔在经过磷酸浸泡以及电解液水煮之后,各项性能参数波动幅度均较小,表明复合氧化膜电极箔极具市场潜力。