Papers

ICMCTF2002 Session F3-2: Surface and Thin Film Analysis

Wednesday, April 24, 2002 1:30 PM in Room San Diego

Wednesday Afternoon

Start	Invited?	Item
1:30 PM		F3-2-1 Influence of Process Gas Mixtures on TiN Coatings Produced by Electron Beam Evaporation PAPVD A. Davison, A.D. Wilson, A. Leyland, A. Matthews, K.S. Fancey (University of Hull, United Kingdom) Titanium nitride coatings have been deposited by plasma-assisted physical vapour deposition (PAPVD) using an electron beam evaporation source. Examination of alternative carrier gases and partial pressures has been carried out in order to determine whether the process can be further optimised, in terms of, for example, attaining lower deposition temperatures: this would increase the range of materials that can be coated (e.g. low cost steels and aluminium alloys). The work looks into the nature of the species within the plasma, as well as those arriving at the substrate and their influence on the coating characteristics. This is achieved through mass/energy analysis at the substrate (cathode) and optical emission spectroscopy in the plasma. Coating evaluation by SEM, EDX and Knoop microhardness is correlated with the process data.
1:50 PM		F3-2-2 A Comparative Study of Sliding Wear of 0.2 % Carbon Steel Coatings Deposited by Hvof and Ptwa Thermal Spray Processes A. Edrisy, A.T. Alpas (University of Windsor, Canada) Sliding wear behaviour of low carbon (0.2% C) steel coatings produced using i) a plasma transfer wire arc thermal spraying (PTWA), and ii) a high velocity oxyfuel (HVOF) process were compared. The wire feed stock used for both coatings was mild steel with a nominal 1020 composition. The coatings had a layered microstructure consisting of steel splats and oxide veins between them. Wear tests were performed using a pin on disc type wear tester within a load range of 10 - 75 N and a sliding speed range of 0.2 - 2.5 m/s against tool steel pins in a dry air atmosphere (10 %RH). The wear rates, frictional forces, and surface temperatures were measured as a function of the applied load and sliding speed. The worn surfaces and the wear debris were characterized with optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and microhardness. At low load and velocity conditions, oxidation (formation of Fe2O3) was the main wear mechanism for both coatings. Severe deformation of the steel splat tips on the contact surface, and their fragmentation was responsible for high wear rates at low velocities and high loads in both PTWA and HVOF coatings. However, the wear rates of HVOF increased considerably at high sliding velocities, this was accompanied with a significant increase in the thickness of the oxide on HVOF worn surfaces, which reached up to10 micrometers at 75N and 2m/s. On the other hand, wear rates of PTWA decreased with increasing sliding velocity. This was associated with hardening of the sliding surface. The wear mechanisms responsible for the differences in the sliding wear behaviour of the coatings will be discussed in terms of in microstructural differences and differences in oxidational kinetics of the coatings.
2:10 PM		F3-2-3 The Analysis of Tungsten Carbide Surfaces and Diamond Thin Films by Laser-acoustic Surface Waves F. Papa, C. Engdahl (Crystallume Engineered Diamond Products); M. Becker, T. Schuelke (Fraunhofer USA) The chemical vapor deposition of diamond films on cutting tools requires a precisely prepared ceramic substrate. The crystal growth and subsequently the deposition rate of the diamond film depend very sensitively on the availability of freely accessible carbide grain surfaces. A special chemical etching treatment is applied to the incoming tungsten carbide parts to deplete the cobalt binder and to open large grain surfaces as a preparation for the actual diamond deposition process. For quality control purposes it is desirable to have a quick and precise test to evaluate the surface condition of the parts before and after the chemical treatment to monitor the quality of the supplied parts and to ensure consistent surface conditions before the coating process. The propagation of laser-initiated acoustic surface waves has proven to be very sensitive to the condition of treated material surfaces. A non-destructive testing device (LAwaveÂ®) has been used to analyze the surface of a variety of different carbide substrates before and after the chemical preparation to identify how conclusively the toolâ€™s measurement indicates surface conditions that are favorable for diamond thin film growth. Furthermore, the deposited diamond films themselves have been analyzed by laser acoustic waves.
2:30 PM		F3-2-4 The Technology to Analysis the Condition of Rapid Thermal Annealing (RTA) by Optical Second Harmonic Generation K.Y. Lo (National Chiyi University, Taiwan, ROC); Y.L. Wang (Taiwan Semiconductor Manufacturing Company, Taiwan, ROC) Optical Second Harmonic Generation (SHG) has been applied for the analysis of the ULSI process, which including low-energy ion implantation and Rapid Thermal Annealing (RTA). The projected range of low energy ion implantation is about 20nm that the surface layer is destroyed into amorphous by high dose ion implantation, and the surface layer region is recrystallization during RTA process. The symmetrical point group of Si(111) surface layer is 3mm, not like as Si bulk that is centrosymmetry and without dipole contribution. The Reflected SHG of the Si(111) is mainly contributed from the surface dipole and surface quadrupole. The pattern of Reflected SHG vs. azimuthal angle reveals the recrystallized information of amorphous silicon dealt with RTA. It is shown that the well condition of RTA is decided by the SHG technology, which is suitable for the analyzing ULSI process.
3:10 PM		F3-2-6 Growth of TiO₂ Thin Films Using RF Magnetron Sputtering Method and Study of Their Surface Characteristics CheolHo Heo, J.-H. Boo (Sungkyunkwan University, Korea) TiO₂ thin films were successfully grown on Si(100) and micro cover glass substrates using RF magnetron sputtering technique. Different contact angles and crystal growth directions were observed with the various deposition parameters such as annealing temperature, RF power magnitude, and added O₂ amounts. The most proper deposition condition for TiO₂ thin film growth was 150 watt of RF power, 1000 °C of annealing temperature, 1 hour of deposition time, and 15 sccm of O₂. These differences were dependent on a phase transition from Anatase to Rutile structure, and the microhardness was also effected by the phase transformation. Highly oriented, crack-free, stoichiometric polycrystalline TiO₂<110> thin film with rutile phase was obtained after annealing at 1000 °C for 1 hour. The maximum UV/Vis. transmittance and hardness were over 90% and 2000 HK_0.025, respectively. In this study, however, we found that the transmittance and reflectance were strongly influenced by the film thickness and the film surface roughness. The growth rate was increased with RF power magnitude up to 150 watt, and was then decreased due to a sputtering effect. The maximum growth rate observed at 150 watt was 1500 nm/hr.
3:30 PM		F3-2-7 Dark and Phtoconductivity of Amorphous Se-Te-Pb Thin Films M.S. Kamboj, G. Kaur, R. Thangaraj (Guru Nanak Dev University, India) Amorphous thin films of Se_80-xTe₂₀Pb_x (0 ≤ x ≤ 2 ) have been prepared by thermal evaporation technique. Dark and photoconductivity of the samples was measured at different temperatures. The value of dc activation energy (ΔE_a) and the optical band gap ( E_g^opt) for the Se₈₀Te₂₀ is found to be ~ 0.67eV and ~ 1.68eV respectively. Addition of a small percent of Pb (0.6 at%) to the Se-Te system decreases ΔE_a (~ 0.3 eV) and the E_g^opt (~ 1.39 eV) considerably. However the further addition of Pb (up to 2 at%) does not cause much changes in these parameters.The photoconductivity is found to increase with increase in temperature and the intensity of the light used. The square root dependance of the photocurrent on the illumination intensity indicates that the recombination process is bimolecular. The photosensitivity and the differential life time have also been calculated for Se_80-xTe₂₀Pb_x( 0 ≤ x ≤ 2) thin films.