ICMCTF2000 Session B1-2(A): Sputter Techniques and Nano-Structured Thin Films

Monday, April 10, 2000 12:30 PM in Room Golden West

Monday Morning

Start	Invited?	Item
12:30 PM		B1-2(A)-7 Measurements and Modeling of Ionized Physical Vapor Deposition D.N. Ruzic, D.R. Juliano (University of Illinois at Urbana-Champaign) SATIS, a code to model the transport of sputtered material in ionized physical vapor deposition (iPVD) systems, has been used to model a commercial-scale experiment. The system consists of a conventional magnetron designed for 200mm substrates and retrofitted with an auxiliary radio frequency (rf) inductive plasma source located between the target and the substrate. The background gas is Ar and the target material is Cu. The system geometry, secondary plasma parameters, target sputter flux distribution, and background gas conditions are all inputs to the code. The plasma is characterized via a rf-compensated Langmuir probe. A Monte Carlo routine in the code tracks the initially sputtered atoms and keeps track of their electronic state (ions, excited, or neutral). Once they slow sufficiently, they provide input to a diffusion model. In this way, all sputtered atoms are followed until they hit and stick to a surface. The velocity distribution of the sputtered atom population at each surface is calculated. At background pressures of 35 mTorr with 2 kW magnetron power and 700 W inductive power, the calculated ionization fraction for the Cu flux is about 8.7 %, while the experimentally calculated fraction is about 7.5 %. The behavior of the ion and neutral flux, and particularly the ionization fraction, is shown and explained as a function of magnetron power, rf power, plasma density, electron temperature, and background gas temperature.
12:50 PM		B1-2(A)-8 Investigations on Energy Fluxes in Magnetron Sputter-Deposition: Implications for Texturing and Nanoporosity of Metals T.P. Drüsedau, M. Löhmann, F. Klabunde, T.-M. John (Otto-von-Guericke Universität Magdeburg, Germany) By means of TRIM.SP Monte-Carlo Simulations the energetic and angular distributions of sputtered atoms and reflected Argon-neutrals were calculated for sputtering a variety of elemental targets. The simulations resulted in analytical approximations for the calculation of, e.g., the average kinetic energy of the sputtered and reflected species. The power density at the substrate during sputter deposition was measured by a calorimetric method. The combination with measurements of the atomic deposition rate resulted in the determination of the total amount of the energy input per incorporated atom. For low pressure sputtering at typical 0.3 Pa, the experimental data are well described by contributions due to plasma irradiation, the heat of condensation of the deposited atoms, their kinetic energy, and the kinetic energy of the reflected Argon-neutrals. For increased pressure, there is an increased contribution of electrons to probe heating. The combination of experimental and theoretical data results in empirical rules for the energies of the sputtered and reflected species, which allow an estimate of the energy input during sputter-deposition for elemental materials. In a first approximation, the energy per incorporated atom is proportional to the ratio between target atomic mass and sputtering yield. Reflected Argon-neutrals were found to have a strong influence on texture and density of sputter-deposited metals as Mo or W. Because of their strong over-cosine angular distribution, the bombardment of the growing film is inhomogenous using magnetrons in the static deposition mode. This results in lateral inhomogenous texture evolution. Strong thermalization of particles at high-pressure deposition resulted in highly porous films with a typical density below 50 % of the bulk material and a fractal dimension of 2.4 detected by small-angle X-ray scattering.
1:10 PM		B1-2(A)-9 Are There Advantages in the Alloying of W-based Sputtered Hard Coatings With Si? A. Cavaleiro, C. Louro (ICEMS - Departamento de Engenharia Mecânica - FCT da Universidade de Coimbra) W-based sputtered coatings are possible to be deposited with very high hardness and good cohesion/adhesion properties. To improve the in-service behaviour of these coatings, much research work was carried out in order to try to increase their oxidation resistance. These studies are based on the manipulation of the chemical composition of the films by the addition of some chemical elements, such as Ti or Ni. In spite of the improvement obtained on the mechanical properties of the films, no significant increase on their oxidation resistance was reached. In this work, we will discuss the interest of adding Si to W-based coatings and the compromise between the improvement in the oxidation resistance and the decrease in the mechanical properties values. In fact, the addition of Si to W-based coatings has produced much better oxidation behaviour, particularly when the Si contents are higher than 15at%. However, the coatings deposited with this Si content are amorphous and their mechanical properties decreased significantly (e.g. the hardness decreased from 40-45GPa to 20-25GPa). With thermal annealing in vacuum, it is possible to crystallize the amorphous films and to recover the high hardness values. Nevertheless, will there be any interest in this treatment if the most part of the substrates used in the industry do not resist to the high crystallization temperatures (sometimes higher than 900ºC)?
1:30 PM		B1-2(A)-10 Effects of N₂ Concentration in the Discharge Gas on Deposition Rate, Structure and Mechanical Properties of Sputtered Polyimide Thin Films N. Kikuchi (Kanazawa Institute of Technology, Japan); E. Kusano (Advanced Materials R&D Center, Japan); Y. Ikeda, K. Fukushima, A. Kinbara, H. Nanto (Kanazawa Institute of Technology, Japan) Organic polymer thin films with a thickness of <1µmm were deposited on silicon or glass substrate by rf sputtering using polyimide film target with a thickness of 20 µmm in an Ar and N₂ mixture in order to examine effects of N₂ concentration in the discharge gas on deposition rate, film structure, hardness, and durability. Structure of the films was evaluated by Fourier transform infrared spectroscopy (FT-IR). Hardness of the films was measured by nanoindentation using a stylus load of 0.98 mN. Wear test of the films was carried out by a pin-on-flat type reciprocal sliding test using a 10 mm dia. stainless steel ball with a load of 98 mN and the wear resistivity was evaluated by measuring cross section of the wear track on the films after 1000 repetition of the slides. Film deposition rate increased nearly linearly with increasing N₂ concentration, resulting in 12 times larger deposition rate in a pure N₂ compared to that in a pure Ar. IR peaks originated from the amide group were observed for films deposited in the Ar-N₂ mixture gas with a N₂ concentration of >10%, while no significant peak was observed for a film deposited in a pure Ar discharge gas. Reduction of hardness and enhancement of wear resistant of the films were also observed when N₂ was introduced to the sputtering gas. This result closely related to the increase in relative film density. The increase in the deposition rate and the change in structure of the sputtered polyimide films are thought to correlate with fragments sputter-emitted from the polyimide target. It is concluded that the addition of N₂ to the discharge gas strongly influences the deposition rate and film properties of polyimide thin films.