Magnetron sputter deposition: Linking discharge voltage with target properties
TL;DR: The interpretation of the discharge voltage and/or its behavior, especially during reactive magnetron sputtering, is less straightforward as discussed by the authors, and it is necessary to look into the details of the magnetron discharge, the processes occurring at the cathode (or target) and the influence of the important discharge parameters such as discharge current, magnet configuration, and discharge gas pressure.
About: This article is published in Thin Solid Films.The article was published on 2009-03-02. It has received 176 citations till now. The article focuses on the topics: Sputter deposition & Sputtering.
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TL;DR: The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma-based sputtering technology as mentioned in this paper, where high power is applied to the magnetron target in unipolar pulse.
Abstract: The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulse ...
586 citations
TL;DR: In this paper, a step-by-step approach is described for reactive high power impulsive magnetron sputtering (R-HiPIMS), which is a coating technology for high and low sputter yield materials, respectively.
Abstract: High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.
261 citations
TL;DR: In this article, the authors describe the history of thin-film growth by sputter deposition, which required the development of vacuum pumps and electrification of the electrical system to deal with the problem.
Abstract: Thin films, ubiquitous in todays world, have a documented history of more than 5000 years. However, thin-film growth by sputter deposition, which required the development of vacuum pumps and electr ...
188 citations
181 citations
01 Jan 2010
TL;DR: In this paper, the most common approach for growing thin films by sputter deposition is the use of a magnetron source, in which positive ions present in the plasma of magnetically enhanced glow discharge bombard the target.
Abstract: Publisher Summary Sputter deposition is a widely used technique to deposit thin films on substrates. The technique is based on ion bombardment of a source material, the target. Ion bombardment results in a vapor due to a purely physical process, i.e., the sputtering of the target material. This technique is part of the class of physical vapor deposition techniques, which includes thermal evaporation and pulsed laser deposition. The most common approach for growing thin films by sputter deposition is the use of a magnetron source in which positive ions present in the plasma of a magnetically enhanced glow discharge bombard the target. This technique forms the focus of this chapter. The target can be powered in different ways, ranging from direct current (DC) for conductive targets to radio frequency (RF) for nonconductive targets, to a variety of different ways of applying current and/or voltage pulses to the target. Since sputtering is a purely physical process, adding chemistry to, for example, deposit a compound layer must be done ad hoc through the addition of a reactive gas to the plasma, i.e. reactive sputtering. The undesirable reaction of the reactive gas with the target material results in a nonlinear behavior of the deposition parameters as a function of the reactive gas flow. To model this behavior, the fluxes of the various species toward the target must be determined. Equally important are the fluxes of species incident at the substrate because they not only influence the reactive sputter deposition process, but also control the growth of the desired film.
124 citations
References
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Book•
28 Oct 1994
TL;DR: In this paper, the authors introduce the concept of particle and energy balance in discharges and introduce the theory of collision dynamics and wave-heated discharges, as well as chemical reactions and equilibrium.
Abstract: 1. Introduction. 2. Basic Plasma Equations and Equilibrium. 3. Atomic Collisions. 4. Plasma Dynamics. 5. Diffusion and Transport. 6. DC Sheaths. 7. Chemical Reactions and Equilibrium. 8. Molecular Collisions. 9. Chemical Kinetics and Surface Processes. 10. Particle and Energy Balance in Discharges. 11. Capacitive Discharges. 12. Inductive Discharges. 13. Wave-Heated Discharges. 14. DC Discharges. 15. Etching. 16. Deposition and Implantation. 17. Dusty Plasmas. 18. Kinetic Theory of Discharges. Appendix A: Collision Dynamics. Appendix B: The Collision Integral. Appendix C: Diffusion Solutions for Variable Mobility Model.
5,728 citations
Book•
01 Oct 1991
TL;DR: In this article, the authors present an overview of the history of electric discharge physics and its application in the field of gas discharging in the presence of longitudinal gradients of charge density.
Abstract: 1. Introduction.- 1.1 What Is the Subject of Gas Discharge Physics.- 1.2 Typical Discharges in a Constant Electric Field.- 1.3 Classification of Discharges.- 1.4 Brief History of Electric Discharge Research.- 1.5 Organization of the Book. Bibliography.- 2. Drift, Energy and Diffusion of Charged Particles in Constant Fields.- 2.1 Drift of Electrons in a Weakly Ionized Gas.- 2.2 Conduction of Ionized Gas.- 2.3 Electron Energy.- 2.4 Diffusion of Electrons.- 2.5 Ions.- 2.6 Ambipolar Diffusion.- 2.7 Electric Current in Plasma in the Presence of Longitudinal Gradients of Charge Density.- 2.8 Hydrodynamic Description of Electrons.- 3. Interaction of Electrons in an Ionized Gas with Oscillating Electric Field and Electromagnetic Waves.- 3.1 The Motion of Electrons in Oscillating Fields.- 3.2 Electron Energy.- 3.3 Basic Equations of Electrodynamics of Continuous Media.- 3.4 High-Frequency Conductivity and Dielectric Permittivity of Plasma.- 3.5 Propagation of Electromagnetic, Waves in Plasmas.- 3.6 Total Reflection of Electromagnetic Waves from Plasma and Plasma Oscillations.- 4. Production and Decay of Charged Particles.- 4.1 Electron Impact Ionization in a Constant Field.- 4.2 Other Ionization Mechanisms.- 4.3 Bulk Recombination.- 4.4 Formation and Decay of Negative Ions.- 4.5 Diffusional Loss of Charges.- 4.6 Electron Emission from Solids.- 4.7 Multiplication of Charges in a Gas via Secondary Emission.- 5. Kinetic Equation for Electrons in a Weakly Ionized Gas Placed in an Electric Field.- 5.1 Description of Electron Processes in Terms of the Velocity Distribution Function.- 5.2 Formulation of the Kinetic Equation.- 5.3 Approximation for the Angular Dependence of the Distribution Function.- 5.4 Equation of the Electron Energy Spectrum.- 5.5 Validity Criteria for the Spectrum Equation.- 5.6 Comparison of Some Conclusions Implied by the Kinetic Equation with the Result of Elementary Theory.- 5.7 Stationary Spectrum of Electrons in a Field in the Case of only Elastic Losses.- 5.8 Numerical Results for Nitrogen and Air.- 5.9 Spatially Nonuniform Fields of Arbitrary Strength.- 6. Electric Probes.- 6.1 Introduction. Electric Circuit.- 6.2 Current-Voltage Characteristic of a Single Probe.- 6.3 Theoretical Foundations of Electronic Current Diagnostics of Rarefied Plasmas.- 6.4 Procedure for Measuring the Distribution Function.- 6.5 Ionic Current to a Probe in Rarefied Plasma.- 6.6 Vacuum Diode Current and Space-Charge Layer Close to a Charged Body.- 6.7 Double Probe.- 6.8 Probe in a High-Pressure Plasma.- 7. Breakdown of Gases in Fields of Various Frequency Ranges.- 7.1 Essential Characteristics of the Phenomenon.- 7.2 Breakdown and Triggering of Self-Sustained Discharge in a Constant Homogeneous Field at Moderately Large Product of Pressure and Discharge Gap Width.- 7.3 Breakdown in Microwave Fields and Interpretation of Experimental Data Using the Elementary Theory.- 7.4 Calculation of Ionization Frequencies and Breakdown Thresholds Using the Kinetic Equation.- 7.5 Optical Breakdown.- 7.6 Methods of Exciting an RF Field in a Discharge Volume.- 7.7 Breakdown in RF and Low-Frequency Ranges.- 8. Stable Glow Discharge.- 8.1 General Structure and Observable Features.- 8.2 Current-Voltage Characteristic of Discharge Between Electrodes.- 8.3 Dark Discharge and the Role Played by Space Charge in the Formation of the Cathode Layer.- 8.4 Cathode Layer.- 8.5 Transition Region Between the Cathode Layer and the Homogeneous Positive Column.- 8.6 Positive Column.- 8.7 Heating of the Gas and Its Effect on the Current-Voltage Characteristic.- 8.8 Electronegative Gas Plasma.- 8.9 Discharge in Fast Gas Flow.- 8.10 Anode Layer.- 9. Glow Discharge Instabilities and Their Consequences.- 9.1 Causes and Consequences of Instabilities.- 9.2 Quasisteady Parameters.- 9.3 Field and Electron Temperature Perturbations in the Case of Quasisteady-State Te.- 9.4 Thermal Instability.- 9.5 Attachment Instability.- 9.6 Some Other Frequently Encountered Destabilizing Mechanisms.- 9.7 Striations.- 9.8 Contraction of the Positive Column.- 10. Arc Discharge.- 10.1 Definition and Characteristic Features of Arc Discharge.- 10.2 Arc Types.- 10.3 Arc Initiation.- 10.4 Carbon Arc in Free Air.- 10.5 Hot Cathode Arc: Processes near the Cathode.- 10.6 Cathode Spots and Vacuum Arc.- 10.7 Anode Region.- 10.8 Low-Pressure Arc with Externally Heated Cathode.- 10.9 Positive Column of High-Pressure Arc (Experimental Data).- 10.10 Plasma Temperature and V - i Characteristic of High-Pressure Arc Columns.- 10.11 The Gap Between Electron and Gas Temperatures in "Equilibrium" Plasma.- 11. Suslainment and Production of Equilibrium Plasma by Fields in Various Frequency Ranges.- 11.1 Introduction. Energy Balance in Plasma.- 11.2 Arc Column in a Constant Field.- 11.3 Inductively Coupled Radio-Frequency Discharge.- 11.4 Discharge in Microwave Fields.- 11.5 Continuous Optical Discharges.- 11.6 Plasmatrons: Generators of Dense Low-Temperature Plasma.- 12. Spark and Corona Discharges.- 12.1 General Concepts.- 12.2 Individual Electron Avalanche.- 12.3 Concept of Streamers.- 12.4 Breakdown and Streamers in Electronegative Gases (Air) in Moderately Wide Gaps with a Uniform Field.- 12.5 Spark Channel.- 12.6 Corona Discharge.- 12.7 Models of Streamer Propagation.- 12.8 Breakdown in Long Air Gaps with Strongly Nonuniform Fields (Experimental Data).- 12.9 Leader Mechanism of Breakdown of Long Gaps.- 12.10 Return Wave (Return Stroke).- 12.11 Lightning.- 12.12 Negative Stepped Leader.- 13. Capacitively Coupled Radio-Frequency Discharge.- 13.1 Drift Oscillations of Electron Gas.- 13.2 Idealized Model of the Passage of High-Frequency Current Through a Long Plane Gap at Elevated Pressures.- 13.3 V - i Characteristic of Homogeneous Positive Columns.- 13.4 Two Forms of CCRF Discharge Realization and Constant Positive Potential of Space: Experiment.- 13.5 Electrical Processes in a Nonconducting Electrode Layer and the Mechanism of Closing the Circuit Current.- 13.6 Constant Positive Potential of the Weak-Current Discharge Plasma.- 13.7 High-Current Mode.- 13.8 The Structure of a Medium-Pressure Discharge: Results of Numerical Modeling.- 13.9 Normal Current Density in Weak-Current Mode and Limits on the Existence of this Mode.- 14. Discharges in High-Power CW CO2 Lasers.- 14.1 Principles of Operation of Electric-Discharge CO2 Lasers.- 14.2 Two Methods of Heat Removal from Lasers.- 14.3 Methods of Suppressing Instabilities.- 14.4 Organization of Large-Volume Discharges Involving Gas Pumping.- References.
4,306 citations
TL;DR: In this article, the authors present the data and models describing the secondary electrons that initiate the secondary and subsequent feedback avalanches required for the growth of current during breakdown and for the maintenance of low-current, cold-cathode discharges in argon.
Abstract: We review the data and models describing the production of the electrons, termed secondary electrons, that initiate the secondary and subsequent feedback avalanches required for the growth of current during breakdown and for the maintenance of low-current, cold-cathode discharges in argon First we correlate measurements of the production of secondary electrons at metallic cathodes, ie the yields of electrons induced by Ar+ ions, fast Ar atoms, metastable atoms and vuv photons The yields of electrons per ion, fast atom and photon vary greatly with particle energy and surface condition Then models of electron, ion, fast atom, excited atom and photon transport and kinetics are fitted to electrical-breakdown and low-current, discharge-maintenance data to determine the contributions of various cathode-directed species to the secondary electron production Our model explains measured breakdown and low-current discharge voltages for Ar over a very wide range of electric field to gas density ratios E/n, ie 15 Td to 100 kTd We review corrections for nonequilibrium electron motion near the cathode that apply to our local-field model of these discharges Analytic expressions for the cross sections and reaction coefficients used by this and related models are summarized
768 citations
TL;DR: In this paper, a simple model for the reactive sputtering process is described, based on which it is possible to predict the processing behaviour for many different ways of carrying out this process, and also to use the results of the modeling work to scale processes from laboratory size to large industrial processes.
624 citations