ICMCTF2003 Session F5-2: Characterization of Thin Film Growth Mechanism and Evolving Film Properties
Thursday, May 1, 2003 1:30 PM in Royal Palm 4-6
F5-2-1 Monitoring Thin Film Reactions In Situ using Simultaneous X-ray Diffraction, Elastic Light Scattering and Resistance Measurements
C. Lavoie, C. Cabral, Jr., F.M. d'Heurle, J.L. Jordan Sweet, C. Detavernier (IBM T.J. Watson Research Center)
We have used a combination of rapid in situ monitoring techniques during annealing of thin films in order to follow changes in phases, texture, resistivity and surface roughness up to 1100@super o@C as reactions occur. The characterization apparatus combines time-resolved x-ray diffraction, elastic light scattering and resistivity measurements. To attain acceptable diffracted x-ray intensities during annealing of very thin films at rapid rates (RTA), the experiments are performed at the National Synchrotron Light Source (NSLS) X20C beamline at Brookhaven National Laboratory (NY, USA) where an x-ray flux greater than 10@super 13@ photons/s can be achieved. This corresponds to a gain of four orders of magnitude over a state of the art rotating anode XRD system and allows to follow in situ the formation of different phases via the development of their characteristic diffraction patterns. Indeed, the combination of the high x-ray photon flux with a linear position-sensitive detector allows for a diffraction spectrum (14@super o@ in 2@theta@) from a 10 nm metal film to be acquired in less than 100 ms. The experimental apparatus is designed so that one can simultaneously monitor both the resistance of the film and the evolution of the surface conditions via the elastic scattering of monochromatic light. The resistance is measured using a square four point probe geometry while the measurements of roughness are made using HeNe laser light coupled in and out of the annealing chamber with fiber optics. The detection geometry (two detectors) provides information on two lateral length scales of about 0.5 µm and 5 µm. The detection of low intensity scattered light during high temperature anneals requires optical filtering and lock-in detection in order to eliminate intense black body radiation from the sample. @paragraph@ Using these combined techniques, we have studied various thin film reactions for materials relevant to state-of-the-art microelectronic devices. In this talk we will show various examples of materials optimization in microelectronics. We will present results on the advantages and limitations of nickel silicide over the current cobalt silicide used for contacting CMOS devices@super 1,2@. We will also cover examples of diffusion barrier stability and test and selection of metal gate materials@super 3@. Finally, we recently showed that the characterization system can also be used efficiently with solder materials when reaction occurs with liquid metals. The dependence of the rate of intermetallic compound formation on solder composition and under layer metallurgy was measured for some lead free system. We find that this technique is not only sensitive to the formation of intermetallics but also to the undesirable spalling of intermetallics from the interface into the melted solder.@paragraph@@super 1@ C. Lavoie, et al., Effects of alloying elements on cobalt silicide formation, J. Electron. Mater. 31, 597-609 (2002).@paragraph@@super 2@ C. Lavoie, et al., Exploring Thin Film Reactions by means of Simultaneous X-Ray, Surface Roughness and Resistance Measurements, Defect and Diffusion Forum 194-199, 1477 (2001).@paragraph@@super 3@3 C.Cabral, Jr., et al., The use of in situ x-ray diffraction, optical scattering and resistance analysis techniques for evaluation of copper diffusion barriers in blanket and damascene structures, Thin Solid Films 397, 194 (2001).
F5-2-3 Thermal Stability and Crystallization Studies of Amorphous TM-C Films
E. Bauer-Grosse (Ecole des Mines, France)
In this work, several binary Transition Metals(TM)-Carbon systems have been explored with the aim, first, of obtaining amorphous alloys in a wide range of composition, especially towards the carbon-rich concentrations and second, of studying the thermal stability and the crystallization of these new materials. Sputtering has been chosen as means of elaboration to obtain the films and Electron Probe MicroAnalysis was used to determine the composition. The as-sputtered amorphous state was detected by X-ray and/or electron diffraction. For each amorphous film, the thermal stability was studied by Differential Scanning Calorimetry and the crystallization was followed by hot-stage Transmission Electron Microscopy. The products of crystallization were identified by electron diffraction. We present the main results we have got on amorphous and then crystallized films belonging to the well-known Fe-C, Mn-C and Cr-C systems. The thermal stability increases from Fe-C to Cr-C systems. Depending both on the carbon content and the nature of the transition metal, various unknown carbides form from the amorphous films.We find that they are often isomorphous with interstitials compounds already existing among borides, nitrides, carbonitrides and other carbides. The emphasis is put in their structural description. It is thus demonstrated that the new structures can offer either prismatic, octahedral or both sites to the C atoms. This suggests that more than one type of local orders may exist in the amorphous state for these TM-C systems.
F5-2-4 Physical Properties of Magnetron Sputtered ZrN@sub x@ Thin Films
R. Lamni, R. Sanjinés, S.G. Springer, P.E. Schmid, F. Lévy, F.E. Martinez (IPMC-EPFL, Switzerland)
The optical, electrical and mechanical properties of ZrN@sub x@ thin films have been investigated as a The optical, electrical and mechanical properties of ZrN@sub x@ thin films have been investigated as a function of x=N/Zr ratio in the chemical composition range 0.92?x?1.35. The ZrN@sub x@ were deposited by magnetron sputtering at 470K. The optical properties were determined by optical transmission and spectroscopy ellipsometry. Near the stoichiometric composition,the typical parameters of, the fcc ZrN@sub x@ films are: room temperature resistivity ?@sub RT@=140µm?cm, optical reflectivity minimum h?=3.2 eV, nano-indentation hardness H@sub n@=32 GPa, elastic modulus E= 400 GPa. As x increases from 0.92 to 1.30, the physical properties change continuously from metallic into semiconducting behavior. The optical carrier density Nopdecreases following the relationship Nop= N@sub 0@(4-3x) with N@sub 0@= 3.35 1022cm@super -3@. The free electron time decreases from 2.7 10@super -15@to 4.7 10@super -14@s. For 1.30
F5-2-5 Deposition of Low Surface Roughness Iridium for Use in an X-Ray Microscope
N.L. Bassett, J.B. Oliver, O.V. Gotchev, J.P. Knauer (University of Rochester)
The deposition techniques of dc magnetron sputtering and ion-assisted evaporation were examined with the goal of depositing Iridium (Ir) thin films with surface roughness less than 1 nm RMS and density greater than 90% of bulk Ir density for use in an x-ray microscope. Process parameters were optimized for both deposition methods to minimize the surface roughness of the deposited Ir. In all cases, surface roughness was measured using atomic force microscopy. The optimized sputtering process produced the highest quality Ir film, achieving a surface roughness of 0.44 nm RMS and near-bulk film density. Bombardment by energetic particles during the deposition process causes film densification in the Ir film as it is being deposited, and mitigates the columnar growth structure typical of Ir films. Since sputtering is typically a more highly energetic process than ion-assisted evaporation, sputtering is more efficient at producing an Ir film that is more highly dense with lower surface roughness. @paragraph@The optimized sputtering process was used to deposit Ir on a set of super-polished Zerodur® mirrors for use in a high resolution Kirkpatrick-Baez x-ray microscope. This microsope is currently used on the OMEGA UV laser system at the Laboratory for Laser Energetics for x-ray radiography of inertial confinement fusion (ICF) targets. The near-bulk density of the deposited Ir film and the smooth Ir surface have resulted in a high-throughput, low-scattering optic which produces images with high signal to noise ratio. @paragraph@@super 1@This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article.
F5-2-6 Preparation and Characterization of 1-Methoxy-8-Hydroxy-9,10-Anthraquinone Films
A. Mahajan (D. A. V. College, Amritsar, India); R.K. Bedi (Guru Nank Dev University, India)
1-Methoxy-8-hydroxy-9,10-anthraquinone compound has been synthesized and it is thermally evaporated onto the well cleaned glass and KBr substrates kept at different temperatures in a vacuum of 1.3 x 10 @super -3@ Pa. These films are characterized by nuclear magnetic resonance (NMR), optical absorption (IR, visible, near-UV) spectroscopy, X-ray diffraction and scanning electron microscopy. In addition, the electrical properties of the films are determined in the temperature range 290-340 K. @paragraph@ The IR and NMR studies confirmed the formation of 1-methoxy-8-hydroxy-9,10-anthraquinone films. Observations reveal the amorphous behaviour of films deposited below 318K, whereas films deposited at higher temperature show increase in crystallinity. The optical absorption studies indicate that direct interband transition energies lies in the range 1.8-1.99 eV. The current-voltage characteristics of these films show ohmic behaviour of conduction within the investigated field and temperature range (10-60V, 290-340 K). The conduction appears to take place by thermally activated hopping mechanism. The electrical conductivity, carrier concentration and drift mobility of the films increases with increase in substrate temperature, whereas the extinction coefficient and refractive index decreases.
F5-2-7 Characterization of AgGaTe@sub 2@ Films Grown by Hot Wall Technique
R. Kumar (DAV College, India); R.K. Bedi (Guru Nank Dev University, India)
AgGaTe@sub 2@ films have been prepared by hot wall technique in vacuum of 1.3* 10@super -3@ Pa onto the glass substrate kept at different temperatures (483-563K). The experimental conditions were optimized to obtain better crystallinity of the films. The films so prepared were studied for structural, electrical and optical properties. Observations reveal that the crystallinity of the films increases with the increase in substrate temperature. The scanning electron micrographs of the films show an increase in grain size with increasing substrate temperature. It has been observed that the carrier concentration and Hall mobility of films increases with increase in substrate temperature while resistivity decreases. The results indicate that the films are p-type, thus indicating holes as dominant charge carriers. Analysis of optical spectra of the films in the range 300-1100 nm show an allowed direct transition near the fundamental absorption edge (Eg@sub 1@) in addition to a transition originating from crystal field split levels (Eg@sub 2@).