Papers by Keyword: Copper Oxide

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Authors: Kazuki Abe, Akira Izumi
Abstract: Cu has been used as interconnection and lead frame in ULSIs. However, the oxidation and contamination of Cu are not easily avoided. As a result, a thin layer of Cu2O, CuO and carbon contaminations are formed at the Cu surface and these resistances are increased. Therefore, Cu cleaning is necessary. There are some reports to remove Cu oxide layers. Chemical processes such as H2 and NH3 plasma reduction are being investigated [1-5]. These methods have the problem of the plasma damage. Lee et al. proposed Cu oxide reduction using vacuum annealing [6]. However, it seems not suitable for the ULSI process, because the heat-treatment of 400oC is necessary. Therefore, low temperature Cu cleaning without plasma assist is strongly desired. In our previous work, we proposed novel low temperature atomic hydrogen or NH3 decomposed species cleaning generated by heated catalyzer [7,8]. However, in the method it is used 100% hydrogen gas. From the view point of safety, hydrogen gas diluted below explosion limit is preferred to use. In this paper we proposed a novel Cu cleaning method by atomic hydrogen generated on a heated tungsten catalyzer using diluted hydrogen as a cleaning gas.
Authors: Nezar Gassem Elfadill, M. Roslan Hashim, Khaled M. Chahrour, Chun Sheng Wang
Abstract: Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}Nanocrystalline cupric oxide (CuO) film was prepared by sputtering of pure copper metal on n-type single crystalline Si substrate under argon-oxygen ambient. Structural and morphological analyses of the as-deposited CuO films were performed by X-ray diffraction (XRD) diffractometer and Field Emission Scanning Electron Microscopy (FESEM). The results show Single crystalline granular nanocrystalline (002) CuO films, with 18 nm crystallite size. Current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed for p-CuO/n-Si hetrojunction. Diode parameters such as saturation current (Is=9.5E-6 A) and ideality factor (n=1.86) were extracted from the dark I-V characteristics. Potential barrier height of the junction (ϕi=1.1V) was revealed from (1/C2- V) plot. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}
Authors: Francesco Pipia, Annamaria Votta, Alice C. Elbaz, Salvo Grasso, Enrica Ravizza, Simona Spadoni, Mauro Alessandri
Abstract: In damascene architecture, widely used both in flash memories and in DRAM as interconnect scheme since 90 nm node, copper surface is exposed after via etch. A deep understanding of the effect of different wet cleanings on Cu surface is therefore mandatory, not only to ensure an efficient post etch polymer removal, but also to provide a better surface termination, capable to minimize Cu oxidation kinetic and to reduce the growth of Cu-rich precipitates which may negatively effect contact resistance. In this work we have analyzed the Cu surface after processing with several cleaning chemistries -often present in BEOL cleaning processes- using XPS (X-ray Photoelectron Spectroscopy) and ToF-SIMS (Time of Flight – Secondary Ion Mass Spectroscopy), fast and powerful techniques widely used in Cu surface characterization [1]. In addition, the evolution of the surface with storage time has been monitored using the same techniques, in order to better understand the effect of the different cleaning chemistries. XPS has been proven to be very sensitive to monitor Cu oxidation, while ToF-SIMS has been used to reveal organic species adsorbed on the surface.
Authors: Dewi Suriyani Che Halin, Ibrahim Abu Talib, Abdul Razak Daud, Muhammad Azmi Abdul Hamid
Abstract: Copper oxide films were prepared via sol-gel like spin coating starting from methanolic solutions of cupric chloride onto the TiO2 substrates. Films were obtained by spin coating under room conditions (temperature, 25-30 °C) and were subsequently annealed at different temperatures (200-400 °C) in oxidizing (air) and inert (N2) atmospheres. X-ray diffraction (XRD) patterns showed crystalline phases, which were observed as a function of the annealing conditions. The film composition resulted single or multi-phasic depending on both temperature and atmosphere. The grain size of film was measured using scanning electron microscopy (SEM) and the surface roughness of thin films was characterized by atomic force microscopy (AFM). The grain size of which was annealed in air at 300 °C was 30.39 nm with the surface roughness of 96.16 nm. The effects of annealing atmosphere on the structure and morphology of copper oxide thin films are reported.
Authors: Ramesh Singh, K.L. Aw, C.H. Ting, Chou Yong Tan, Iis Sopyan, Wan Dung Teng
Abstract: The effect of adding small amounts of copper oxide (CuO) on the sintering and mechanical properties of alumina ceramic was studied. Samples were prepared and fired in air atmosphere at temperatures ranging from 1400oC to 1600oC. Sintered samples were characterized to determine phase present, bulk density, hardness and grain size. The results indicated that all the doped samples could be sintered to high density > 3.85 Mgm−3 when compared to the undoped alumina. According to the XRD analysis, the α-Al2O3 phase was not disrupted by the dopant addition. Although the hardness of the CuO-doped material was higher when sintered below 1550°C, the maximum hardness of 21 GPa was measured for the undoped ceramics when sintered at 1600°C. The lower hardness of the doped samples could be attributed to the increased in grain size with increasing sintering temperature.
Authors: Zhen Qiang Zhao, Xin Ping Ouyang
Abstract: The effect of three kinds of oxidants, hydrogen peroxide, copper oxide and ammonium persulfate, on the structures and properties of modified lignin were investigated. It is found out that a low dosage of oxidant can result in the increase in the content of active phenolic hydroxyl and carboxyl. It is most likely to cleave β-O-4 and C-C bond in lignin molecule. Compared to ammonium persulfate and copper oxide, hydrogen peroxide exhibits relatively mild oxidation to lignin. The oxidation of lignin with excessive ammonium persulfate and hydrogen peroxide can cause free radical polymerization of alkali lignin, leading to the increase of molecular weight and the decrease of the sulfonation degree of the sulfonated lignin followed by oxidation and hydroxymethylation (OSAL). Ammonium persulfate exhibits a stronger capacity to initiate free polymerization reaction compared to hydrogen peroxide, so it is suitable to use a low dosage of ammonium persulfate for the oxidation of alkali lignin. Copper oxide could not cause a free radical polymerization, therefore the molecular weight of the sulfonated lignin is lower, and the sulfonation degree is higher. OSAL with a good dispersive effect to cement paste should simultaneously possess a high sulfonation degree and an appropriate molecular weight.
Authors: M.J. Chiang, C.W. Wu, H.E. Cheng
Abstract: Copper oxide, a direct band gap semiconductor with band gap about 1.21-1.51 eV, has been regarded as a promising material for photovoltaic. Nanocrystalline copper oxide films have been synthesized on Si by dc sputtering method. The effects of oxygen flow rate and deposition temperature on the microstructure of nanocrystalline copper oxide films were investigated. X-ray diffraction analysis shows that a broaden peak of Cu2O (111) at 36.720 was observed at the deposition condition of DC power 150 W, pressure 2*10-2 Torr, substrate temperature 100 °C, Ar flow rate 15 sccm and O2 flow rate 1sccm. With increasing the oxygen flow rate to 3 and 5 sccm, CuO (-111) could be observed at 36.58o. The increase of oxygen flow rate resulted in the film formation from Cu2O to CuO. SEM pictures show that copper oxide films exhibit nanosize grains. X-ray diffraction patterns of CuO films deposited at 50~200 °C show that only (-111) plane is obtained. The SEM pictures show that the grain size increases with the deposition increases.
Authors: Hidayani Jaafar, Zainal Arifin Ahmad, Mohd Fadzil Ain
Abstract: The structure and dielectric properties of Barium Zinc Tantalate (BZT) doped by copper oxide (CuO) with a variety of values of mol% doping from 0, 0.1, 0.25, 1.0, 1.5 and 2.5 were prepared using a solid state method. The addition of CuO did not disturb the 1:2 ordering structure of the BZT ceramic. The grain size increased when the addition of doping increased. A small amount of doping elements increased the relative density. The dielectric constant (ɛr) value of the BZT significantly improved with the addition of the CuO for the specimens sintered at 1250°C and it could be explained by the increase of the relative density. The tan δ of the CuO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CuO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is produced when it is doped with 0.25 mol% CuO and sintered at 1250°C. The best microwave dielectric properties obtained were ɛr=70.28, tan δ = 0.024, %BW = 7.83 which occurred for the 0.25 mol% doped CuO and when sintered at 1250°C/4 h.
Authors: Jia Wei Low, Nayan Nafarizal, Mohd Zainizan Sahdan, Mahamad Abd Kadir, Mohd Khairul bin Ahmad, Md Shakaff Ali Yeon, Zakaria Ammar, Fathinul Syahir Ahmad Saad, Ahmad Faizal Mohd Zain
Abstract: There are several techniques to deposit the metal oxide thin film such as electron beam evaporator, pulse laser deposition and reactive magnetron sputtering deposition. In this experiment, magnetron sputtering deposition techniques will be used to produce a copper oxide thin film due to its simplicity and repeatability performance. Recently, copper oxide thin film has been studied because of its low cost material, sensitivity to ambient condition and easiness to produce oxide thin film. It is one of the p-type semiconductor oxides materials that are suitable to be used as a gas sensing material. In order to increase the sensitivity and to optimize the properties of copper oxide thin film, it is essential to study on the plasma properties during the deposition of copper oxide. In current studies, Langmuir probe was used to investigate the effect of substrate bias towards the fabrication of copper oxide thin film at rf dissipation power of 400 W. The oxygen flow rate was fixed at 8sccm. The Langmuir probe tip was focus at roughly 2 cm above the substrate holder. The ion and electron current were collected from the plasma environment. Then the electron temperature, electron density, ion density, ion flux, Debye length and plasma potential at various substrate biases were evaluated from the current-voltage curve. The electron temperature at various oxygen flow rates was almost unchanged. The effect of substrate bias toward the electron temperature was also almost unseen, except that the electron temperature at-40 V bias voltage was slightly lower than others. In addition, the ion flux at the same plasma condition shows that the ion flux was higher at-40 V substrate bias voltage. The results suggest that the ion bombardment effect toward the deposited copper oxide thin film would be higher at low oxygen flow rate. Thus it will create a rough surface morphology or nanostructured copper oxide thin film. This is a potential ways to improve the sensitivity of copper oxide gas sensor.
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