skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: High-power pulsed sputtering using a magnetron with enhanced plasma confinement

Abstract

High-power pulsed dc magnetron discharges for ionized high-rate sputtering of metallic films were systematically investigated. The depositions were performed using two unbalanced circular magnetrons of different types with a directly water-cooled planar copper target of 100 mm in diameter. The repetition frequency was 1 kHz at a fixed 20% duty cycle and an argon pressure of 0.5 Pa. Time evolutions of the discharge characteristics were measured to provide information on absorption of energy in the discharge plasma and on transfer of arising ions to the substrate at a target power density in a pulse up to 950 W/cm{sup 2}. Time-averaged mass spectroscopy was performed at the substrate position to characterize ion energy distributions and composition of total ion fluxes onto the substrate. The deposition rate of the copper films formed on a floating substrate at the distance of 100 mm from the target was 2.2 {mu}m/min at an average target power density over a pulse period of 96 W/cm{sup 2}. Very effective ionization of sputtered copper atoms resulted in a strong predominance of copper ions (up to 92%) in total ion fluxes onto the substrate. Trends in measured values of the deposition rate per average target power density and themore » ionized fraction of sputtered copper atoms in the flux onto the substrate (up to 56%) were explained on the basis of model predictions.« less

Authors:
; ; ;  [1]
  1. Department of Physics, University of West Bohemia, Univerzitni 22, 30614 Plzen (Czech Republic)
Publication Date:
OSTI Identifier:
20853949
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 25; Journal Issue: 1; Other Information: DOI: 10.1116/1.2388954; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ARGON; COPPER; COPPER IONS; DEPOSITION; HIGH-FREQUENCY DISCHARGES; MAGNETRONS; MASS SPECTROSCOPY; PLASMA CONFINEMENT; POWER DENSITY; SPUTTERING; SUBSTRATES; THIN FILMS

Citation Formats

Vlcek, Jaroslav, Kudlacek, Pavel, Burcalova, Kristyna, and Musil, Jindrich. High-power pulsed sputtering using a magnetron with enhanced plasma confinement. United States: N. p., 2007. Web. doi:10.1116/1.2388954.
Vlcek, Jaroslav, Kudlacek, Pavel, Burcalova, Kristyna, & Musil, Jindrich. High-power pulsed sputtering using a magnetron with enhanced plasma confinement. United States. doi:10.1116/1.2388954.
Vlcek, Jaroslav, Kudlacek, Pavel, Burcalova, Kristyna, and Musil, Jindrich. Mon . "High-power pulsed sputtering using a magnetron with enhanced plasma confinement". United States. doi:10.1116/1.2388954.
@article{osti_20853949,
title = {High-power pulsed sputtering using a magnetron with enhanced plasma confinement},
author = {Vlcek, Jaroslav and Kudlacek, Pavel and Burcalova, Kristyna and Musil, Jindrich},
abstractNote = {High-power pulsed dc magnetron discharges for ionized high-rate sputtering of metallic films were systematically investigated. The depositions were performed using two unbalanced circular magnetrons of different types with a directly water-cooled planar copper target of 100 mm in diameter. The repetition frequency was 1 kHz at a fixed 20% duty cycle and an argon pressure of 0.5 Pa. Time evolutions of the discharge characteristics were measured to provide information on absorption of energy in the discharge plasma and on transfer of arising ions to the substrate at a target power density in a pulse up to 950 W/cm{sup 2}. Time-averaged mass spectroscopy was performed at the substrate position to characterize ion energy distributions and composition of total ion fluxes onto the substrate. The deposition rate of the copper films formed on a floating substrate at the distance of 100 mm from the target was 2.2 {mu}m/min at an average target power density over a pulse period of 96 W/cm{sup 2}. Very effective ionization of sputtered copper atoms resulted in a strong predominance of copper ions (up to 92%) in total ion fluxes onto the substrate. Trends in measured values of the deposition rate per average target power density and the ionized fraction of sputtered copper atoms in the flux onto the substrate (up to 56%) were explained on the basis of model predictions.},
doi = {10.1116/1.2388954},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 1,
volume = 25,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • Metastable NaCl-structure Ti{sub 1-x}Al{sub x}N is employed as a model system to probe the effects of metal versus rare-gas ion irradiation during film growth using reactive high-power pulsed magnetron sputtering (HIPIMS) of Al and dc magnetron sputtering of Ti. The alloy film composition is chosen to be x = 0.61, near the kinetic solubility limit at the growth temperature of 500 Degree-Sign C. Three sets of experiments are carried out: a -60 V substrate bias is applied either continuously, in synchronous with the full HIPIMS pulse, or in synchronous only with the metal-rich-plasma portion of the HIPIMS pulse. Alloy filmsmore » grown under continuous dc bias exhibit a thickness-invariant small-grain, two-phase nanostructure (wurtzite AlN and cubic Ti{sub 1-x}Al{sub x}N) with random orientation, due primarily to intense Ar{sup +} irradiation leading to Ar incorporation (0.2 at. %), high compressive stress (-4.6 GPa), and material loss by resputtering. Synchronizing the bias with the full HIPIMS pulse results in films that exhibit much lower stress levels (-1.8 GPa) with no measureable Ar incorporation, larger grains elongated in the growth direction, a very small volume fraction of wurtzite AlN, and random orientation. By synchronizing the bias with the metal-plasma phase of the HIPIMS pulses, energetic Ar{sup +} ion bombardment is greatly reduced in favor of irradiation predominantly by Al{sup +} ions. The resulting films are single phase with a dense competitive columnar structure, strong 111 orientation, no measureable trapped Ar concentration, and even lower stress (-0.9 GPa). Thus, switching from Ar{sup +} to Al{sup +} bombardment, while maintaining the same integrated incident ion/metal ratio, eliminates phase separation, minimizes renucleation during growth, and reduces the high concentration of residual point defects, which give rise to compressive stress.« less
  • Both the industrially favorable deposition technique, high power impulse magnetron sputtering (HIPIMS), and the industrially popular rotating cylindrical magnetron have been successfully combined. A stable operation without arcing, leaks, or other complications for the rotatable magnetron was attained, with current densities around 11 A cm{sup -2}. For Ti and Al, a much higher degree in ionization in the plasma region was observed for the HIPIMS mode compared to the direct current mode.
  • The modulated pulsed power magnetron sputtering (MPPMS) discharge processes are numerically modeled and experimentally investigated, in order to explore the effect of the pressure on MPPMS discharges as well as on the microstructure of the deposited thin films. A global plasma model has been developed based on a volume-averaged global description of the ionization region, considering the loss of electrons by cross-B diffusion. The temporal variations of internal plasma parameters at different pressures from 0.1 to 0.7 Pa are obtained by fitting the model to duplicate the experimental discharge data, and Cu thin films are deposited by MPPMS at the correspondingmore » pressures. The surface morphology, grain size and orientation, and microstructure of the deposited thin films are investigated by scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. By increasing the pressure from 0.1 to 0.7 Pa, both the ion bombardment energy and substrate temperature which are estimated by the modeled plasma parameters decrease, corresponding to the observed transition of the deposited thin films from a void free structure with a wide distribution of grain size (zone T) into an underdense structure with a fine fiber texture (zone 1) in the extended structure zone diagram (SZD). The microstructure and texture transition of Cu thin films are well-explained by the extended SZD, suggesting that the primary plasma processes are properly incorporated in the model. The results contribute to the understanding of the characteristics of MPPMS discharges, as well as its correlation with the microstructure and texture of deposited Cu thin films.« less
  • A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbon deposits on a gold magnetron sputter target and carbon impurities in the gold matrices of deposited films were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used tomore » determine that a likely mechanism for generation of carbon impurities was a reaction between toluene vapor generated from the MAPLE target and the argon plasma originating from the magnetron sputtering process. Carbon impurities of codeposited films were significantly reduced by introducing argon-oxygen mixtures into the deposition chamber; reactive oxygen species such as O and O+ effectively removed carbon contamination of gold matrix during the codeposition processes. Increasing the oxygen to argon ratio decreased the magnetron target sputter rate, and hence hybrid process optimization to prevent gold matrix contamination and maintain a high sputter yield is needed. High resolution TEM with energy dispersive spectrometry elemental mapping was used to study carbon distribution throughout the gold matrix as well as embedded CNP clusters. This research has demonstrated that a hybrid MAPLE and magnetron sputtering codeposition process is a viable means for synthesis of composite thin films from premanufactured nanoscale constituents, and that cross-process contaminations can be overcome with understanding of hybrid plasma process interaction mechanisms.« less
  • Results are presented from experimental studies of the current-voltage characteristics and spatial and temporal parameters of the plasma in a high-current pulsed magnetron sputtering system with a 10-cm-diameter plane disk cathode. It is shown that the plasma density in such a system is three orders of magnitude higher than that in conventional dc magnetron discharges and reaches 10{sup 13} cm{sup -3} at a distance of 250 mm from the cathode at a peak discharge current of 500 A. The plasma propagates from the cathode region at a velocity of 1 cm/{mu}s in the axial direction and 0.25 cm/{mu}s in themore » radial direction. Optical emission spectroscopy shows that the degree of plasma ionization increases severalfold with increasing discharge current, mainly at the expense of the sputtered material.« less