Papers

ICMCTF2004 Session F5: Characterization of Thin Film Growth Mechanism and Evolving Film Properties

Monday, April 19, 2004 1:30 PM in Room Sunrise

Monday Afternoon

Start	Invited?	Item
1:30 PM		F5-1 Nucleation, Growth and Properties of Magnetically Doped TiO₂ Anatase and Rutile S.A. Chambers (Pacific Northwest National Laboratory) Magnetically doped TiO₂ has emerged as one of the most intriguing and promising ferromagnetic oxide semiconductors for potential application in the emerging field of spintronics. The nucleation and growth of these materials are complex and do not obey existing models. In this talk, I will review what is known about this fascinating and potentially important class of materials, with special attention being paid to the role of the growth method in determining the resulting structural, electronic and magnetic properties.
2:10 PM		F5-3 A Novel Method of Forming Germanium Nanocrystals Embedded in Silicon Oxidized-nitride(SiON) M.C. Wang (National Tsing Hua University, Taiwan, R.O.C.); T.C. Chang (National Sun Yat-Sen University, Taiwan, R.O.C); P.T. Liu (National Nano Device Laboratory, Taiwan, R.O.C.); P.H. Yeh (National Tsing Hua University, Taiwan, R.O.C.); Y.T. Chen (National Sun Yat-Sen University, Taiwan, R.O.C.); C.H Tu (National Chiao Tung University, Taiwan, R.O.C.); J.R. Chen (National Tsing Hua University, Taiwan, R.O.C.) We reported a novel method of forming germanium nanocrystals embedded in silicon oxidized-nitride (SiON). By using Plasma Enhanced Chemical Vapor Deposition (PECVD) system to deposit SiGeN film 300nm on 4 inch P-type silicon wafer at 350°C. The Ge nanocrystals were synthesized by thermal oxidation at 1000°C 10 minutes in furnace of the PECVD deposited SiGeN film. The hysteresis of the C-V curve was observed in our metal-insulator-semiconductor structure. Transmission electron microscopes (TEM), Fourier transform infrared (FTIR) spectra and C-V results indicated that the hysteresis was due to Ge nanocrystals in the insulator layer.
2:30 PM		F5-4 The Thermal Stability of Cu/FSG Structure with Amorphous and Crystalline Tantalum Nitrides Diffusion Barriers C.C. Chang, J.S. Chen (National Cheng Kung University, Taiwan, R.O.C.) This work investigates the thermal interactions of Cu/Ta-N/Ta/fluorinated silicate glass (FSG) structures after annealing up to 900°C, where Ta-N layers were as-deposited amorphous TaN_x (x~0.5) or polycrystalline TaN films. It is found that both the TaN_x and TaN barriers possess excellent capability to prevent Cu from diffusion after annealing up to 700°C. After annealing at 800°C, however, in-diffusion of Cu and the out-diffusion of fluorine in the Cu/Ta-N/Ta/FSG structures can be observed when examining with Auger electron spectrometry. Furthermore, after annealing at 900°C, oxidation of the Cu/TaN_x/Ta/FSG structure was detected by glancing incident angle X-ray diffraction, but oxidation was not found in the Cu/TaN/Ta/FSG structure. X-ray photoelectron spectroscopy also indicates that the amount of Ta-O bondings was greater in the TaN_x film than in the TaN film after annealing at 900°C. However, the agglomeration of Cu layer on Cu/TaN/Ta/FSG was more serious than on Cu/TaN_x/Ta/FSG after annealing at 900°C. The serious agglomeration of Cu on TaN will increase its sheet resistance to a greater value than that of Cu/TaN_x/Ta/FSG system, although the TaN layer was not oxidized as significant as the TaN_x layer.
2:50 PM		F5-5 Damage Effect Caused by Fluorine Ion Implantation in Plasma Enhanced Chemical Vapor Deposited A-SiOC Barrier Dielectric F.M. Yang (National Chiao Tung University, Taiwan, R.O.C.); T.C. Chang (National Sun Yat-Sen University, Taiwan, R.O.C); P.T. Liu (National Nano Device Laboratory, Taiwan, R.O.C.); C.W. Chen, J.C. Lou (National Chiao Tung University, Taiwan, R.O.C.) The conventional barrier dielectric SixNy with a large dielectric constant (k~8) is not suitable to be used in the multilevel interconnection. To reduce the effective k value, SixCy (k=4~6) is currently utilized as a diffusion barrier and etch stop layer in dual Damascene structure. In this study, amorphous SiOC (a-SiOC) films which have various concentrations of oxygen were controlled by O2 gas flow rate during PECVD process. After fluorine (F) ion implanted into a-SiOC film, it was found that the leakage current in carbide film was increased from the electrical characterization due to the generation of traps. Afterwards, the traps were repaired which leads to the decrease of leakage current after thermal annealing. From the fitting of the current-voltage (J-E) characteristics, the conducting mechanism of the leakage current still obeys Poole-Frenkel conduction for intrinsic or F-implanted and annealed samples. Also, the barrier height of the F-implanted and annealed sample is extracted and reduced to a lower value than the intrinsic sample.
3:10 PM		F5-6 Material Microstructural Influence on Spiral Thin Film Inductors K.Y. Hsu, C.P. Liu (National Chung Kung University, Taiwan, R.O.C.) With the trend of higher operation frequencies in wireless communication (>1GHz), the integration of all discrete passive devices on a silicon substrate is a must, of which the fabrication of thin-film inductors is a challenge. Although the research on the thin-film inductor has been conducted for more than 10 years, litter research was focused on the dependence of the material microstructures on the inductor characteristics. In this paper, we fabricate planar spiral thin-film inductor by typical integrated circuit processes, and the inductor structure is fixed for the design of the optimum property. We then examine the inductor properties, including inductance and quality factor as function of the variety of the material used in the inductor and buffer layers. The materials are characterized by four-point probe, x-ray diffraction and dielectric measurement. The materials used for the inductor include copper with strongly (111) and (002) preferred orientations and different conductivities, which is compared to magnetic cobalt materials, while those for the buffer layer include silicon dioxide (SiO2), organic silicon glass (OSG) and polyimide. The results show that the ohmic loss can be effectively reduced by the better conductivity and stronger textures, which results in better quality factor at high frequencies. We also show the inductor properties also depend on the buffer layer materials. The mechanisms will be discussed in this paper.
3:30 PM		F5-7 High-temperature Self-grown ZrO₂ Layer Against Cu Interdiffusion at Cu(Zr)/SiO₂ Interface C.J. Liu, J.S. Chen (National Cheng Kung University, Taiwan, R.O.C.) In this work, pure Cu and Cu(2.45 at.% Zr) alloy films were deposited on SiO₂/Si substrates by magnetron sputtering. All samples were subsequently annealed at various temperatures ranging from 500° to 800° in vacuum to investigated the difference of thermal stability between Cu and Cu(2.45 at.% Zr) systems. Upon annealing, the addition of Zr in Cu(2.45 at.% Zr) out-diffuse to both the free surface and alloy/SiO₂ interface, and reacts with the residual oxygen to form a ZrO₂ layer. This self-grown ZrO₂ layer plays an important role in preventing the Cu from diffusion into SiO₂ after annealing at 700°, while the interdiffusion is apparent for pure Cu on SiO₂ at this temperature. Concurrently, the annealing processes reduce the resistivity of pure Cu and Cu(Zr) alloy. However, the resistivity reduction of Cu(2.45 at.% Zr) is more evident than that of pure Cu, which is related with the segregated of Zr additives. In addition, by using the scanning electron microscopy, the morphology of the Cu(2.45 at.% Zr) film remains smooth after annealing up to 800°, while the Cu film becomes discontinuous. The relation between the out-diffusion of Zr additives and the microstructure/interfacial characteristics of Cu(2.45 at.% Zr) is also discussed.
3:50 PM		F5-8 Effect of pH on Morphological Features and Growth Behaviors of Electrochemically Deposited Cu₂O Thin Film Y.H. Lee, I.C. Leu, H.C. Yu, K.Z. Fung (National Cheng Kung University, Taiwan, R.O.C.) The Cu₂O thin films were successfully deposited by electrochemical deposition by the galvanostatic technique. In order to avoid the formation of Cu+Cu₂O composite, the experiments were performed at the low current density with pH of solution between 9 and 11. The glancing angle XRD and XPS analysis were taken to examine the crystal structure and binding energy of films. SEM and TEM were used to observe the morphology and microstructure of deposited films. The effect of pH on the morphological features and growth behavior of Cu₂O films were examined by SEM and TEM observation. At low pH range, the topography was four-sided pyramid while the triangular pyramids were obtained at higher pH conditions. The cross sectional observation of Cu₂O film indicated that the columnar growth dominated at low pH, while the repeated nucleation process dominated the growth at high pH. Such a difference was ascribed to the influence of [OH-] on the nucleation and growth behavior.
4:10 PM		F5-9 In Search of New Materials in the V_1-xC_x Films A. Aouni (FST Tanger Maroc, France); P. Weisbecker (LSG2M Ecole des mines de Nancy, France); T. Huu Loi, E. Bauer-Grosse (LSGS Ecole des Mines de Nancy, France) In this work, the Vanadium-carbon system has been explored in a wide range of carbon content (0.02< x<0.69) with the aim of obtaining films of new materials. The Films were prepared by diode magnetron sputtering and Electron Probe MicroAnalysis was used to determine their composition. The as-sputtered states were identified by X-ray and TEM. We can show that they strongly depend on the carbon content. Except a narrow range of carbon content around x=0.32, most of the films are crystalline and contain phases related to the phase diagram but several interesting facts can be underlined. Below x=0.32 and with an increasing carbon content the carbon solubility in the bcc vanadium solid solution is considerably increased (up to 0.17) inducing a lattice parameter expansion. Then films become mainly amorphous around x=0.32, value very near from the carbon content of the hemicarbide V₂C. Finally, for higher carbon contents, the films are mostly constituted with the VC monocarbide existing in a wide range of carbon content. For x=0.32, TEM images and associated diffraction pattern suggest a nanocomposite material with numerous little crystals of carbide embedded in an amorphous matrix. A special attention has been devoted to this composition and a crystallization study has been undertaken. These first results suggest perhaps to retain the V-C system among the candidates for hard or ultra-hard films.
4:30 PM		F5-10 Multilayer Formation by a Postdischarge Nitriding Followed by Paste Boriding I Campos (ITESM-CCM, Mexico); J. Oseguera (ITESM-CEM, Mexico); U. Figueroa, O. Bautista, R. Ganem, M. Sanchez (ITESM-CCM, Mexico) Nitrogen and boron were diffused into the surface of ARMCO iron, SAE 1010 and 1060 steels under conditions of two temperature-stage processes. Diffusion of nitrogen was carried out at 650°C in a post-discharge assisted nitriding process, while diffusion of boron occurred at 920°C in a paste boriding process. The microstructure obtained after the first stage shows a flat morphology with high hardness due to the formation of nitrogen compounds. No change in the morphology was observed after the boriding stage. The x-ray diffractometry analysis shows the distribution of nitrogen and boron on the layer obtained. Higher hardness and a less steep hardness gradient was obtained in comparison with a sample post-discharge nitriding and boriding methods, This resulted in a higher adhesion of the boro-nitride layer to the substrate.