Develops detailed understanding of the deposition and etching of materials by sputtering discharge, and of etching of materials by chemically active discharge. The magnetic field concentrate and intensifies the plasma in the space immediately above the target, as a result of trapping of electrons near the target surface. A glow discharge is a plasma formed by the passage of electric current through a lowpressure gas. Sputtering effectively knocks off the material to be sputtered via a high energy, ionized atom typically ar.
Inclusions with areas greater than this critical value readily induce arcing and. By first creating a gaseous plasma and then accelerating the ions from this plasma into some source material a. The drop occurs across thin dark space regions between the plasma and. However, it doesnt happen for higher dc voltage and for rf sputtering. Plasma sputter coating in conventional sem sputter coating a gold goldpalladium, or platinum target is bombarded with heavy gas atoms usually argon but air is a fair substitute. Rf plasma sputtering target substrate vplasma plasma potential still v 0 due to high evelocity, charging of surfaces.
Sputtering a compound target may not give what one wants. Plasma characterization and thin film growth and analysis. A plasma, at any given pressure, will find an equilibrium of. Theory and practice of rf sputtering sciencedirect.
Certainly reactive sputtering can be done using dc sputtering, whereas compound target insulating can only be used for rf sputtering. Plasma sputtering covers a range of technologies known by a variety of names including advanced plasma sputtering and magnetron sputtering. Sputter deposition is also a line of sight technique similar to plasma spraying. It occurs naturally in outer space, and can be an unwelcome source of wear in precision components. The pinnacles and buttes were parts of the dome where an arc or many arcs struck and dissipated builtup charge. Subjects range from voltage, distributions encountered in plasma etching systems to plasma. The general requirements are a source of electrons, a small region. The general concept is rooted in the generation of plasma. The authors dark plasma theory, published first in 2006, holds that a substantial amount of this dark matter is composed of plasma and radiates dark light. Metal atoms ejected from the target by the ionized gas cross the plasma to deposit onto the any surface within the coating unit including the specimen. Sputtering free download as powerpoint presentation. There, film redeposition induces filament or nodule growth. An apparatus is presented, with a rotating target 18, 15, which is tubularly configured, with a stationary magnet unit 2 disposed within the tube, of a magnetron cathode, which produces a stationary plasma hose provided essentially with two long straight lines in front of the surface of the rotating target, which exercises an erosive action on the surface of the rotating target 18, 15.
Arc generation from sputtering plasmadielectric inclusion. The scientists went further and postulated that dark plasma. In sputtering systems the target is surrounded by dark space shield, also known as a ground shield. As gas pressure is decreased with a glow discharge. Lightning and neon lights are commonplace generators of plasma. However, the fact that it can be made to act on extremely fine layers of material is utilised. The benefits of the microwave plasmas for the reactive sputtering process are demonstrated below. Versatile reactive sputtering batch drum coater with. Given the short publication lifespan of technical books, do not expect to find many in. Sputtering in the presence of a rapid gas flow journal. Rack plasma physics page 18 current and potential distributions in a dc glow discharge 100v cathode anode 1 2 354 v 0 10v most of the voltage drop is across the cathode dark space.
Study of plasma and ion beam sputtering processes 1 the conversion of neutral particles into ions, electrons plasma. Dark space at low pressures, say less than 50 mt, a dark space that is essentially free of ions appears between the electrodes and the plasma. There have been developments aimed at increasing the cathode bombardment to increase the sputtering and hence deposition rate. If local dark point was observed on target, there are some problems such as one is. A voltage is applied between them so that the target is the cathode and the substrate is attached to the anode.
Aug 19, 1997 although the dark space shield and the target are near enough to one another to prevent the plasma from sputtering the backing plate, the gap 126 is large enough to permit sputtered material from the target layer 116 to enter the gap 126 and deposit upon the curved portion 4 of the backing plate 114 and the side wall 128 of the target layer 116. Sputtering rate depends on ion flux to target in dc plasma ion flux j follows childlangmuir equation 2 2 3 m d kv j ion where v voltage difference target to wafer d dark space. The differences between diode, magnetron, balancedunbalanced, rfdc power options, etc. This phenomenon is put to good use in sputtering systems to prevent unwanted sputtering of components held at high voltage. Reference herein to any specific commercial product, process, or service. Full text of sputtering and ionization by helium and argon in the microsecond pulsed glow discharge using timeofflight mass spectrometry. Because the plasma is both electrically neutral and highly conductive, there is little voltage drop across it. Positive ions entering the dark space are accelerated toward the cathode target, bombarding sputtering the target atoms locked out from the target transport to the substrate momentum transfer, not evaporation. In section 2 we introduce ey plasma properties like quasik neutrality, shielding, particle transport processes and sheath formation.
There are a lot of reasons why there may be an arcing problem during the plasma deposition process during sputtering. Greene 2 1 ghent university, department of solid state sciences, krijgslaan 281 s1, 9000 ghent, belgium 2 materials science and physics departments and the frederick seitz materials research laboratory, university of illinois, urbana, illinois 61801, usa sputter deposition is a widely used technique to deposit thin films on substrates. Aug 24, 2012 plasma sputter coater mntjs1600 sputter gold coating. Sputtering is a technique used to deposit thin films of a material onto a surface a. So in sputtering, the target material and the substrate is placed in a vacuum chamber. The sputtering of materials is one of the major uses of plasmas. During magnetron sputter deposition, one source of particle contamination is linked to portions of the sputtering target surface exposed to weaker plasma density. This involves ejecting material from a target that is a source onto a substrate such as a silicon wafer. The pinnacles and buttes were parts of the dome where an arc, or many arcs struck and dissipated builtup charge. The drop occurs across thin dark space regions between the plasma and each electrode.
Target and dark space shield for a physical vapor deposition. The improved target has a portion of the target side wall the overhangs and shadows the side wall of the target thus preventing material from depositing on the edge. When the voltage exceeds a value called the striking voltage, the gas. The disadvantages heretofore associated with the prior art are overcome by the present invention of an improved target for a physical deposition pvd system. When the voltage exceeds a value called the striking voltage, the gas ionization becomes selfsustaining, and the tube glows with a colored light. Full text of sputtering and ionization by helium and.
Review and cite rf sputtering protocol, troubleshooting and other. Jun 20, 20 as with all such things, there will be details to work out in order to establish a good working process procedure for your end product, but the reactive sputtering process can be a very useful tool to have available for creating molecular thin films, especially if there is a need to tinker some with atom ratios stoichiometry in the film in order to control properties such as resistivity for. The ions in this plasma are subsequently accelerated into the source material, striking loose energetic source ions, which then sputter. Crookes dark space it can be seen that there is an abundance of positive. Sputter yield probability ion flux to the target depends on. The material sputtered or knocked off from the sputter target then. A plasma is created by ionizing a sputtering gas generally a chemically inert, heavy gas like argon. I used to deposite titanium oxide by dc magnetron sputtering method and i have to control vacuum.
Sputtering canyons, part 2 the thunderbolts project. This book grew out of lecture notes for an undergraduate course in plasma physics that has been offered for a number of years at ucla. Radio frequency magnetron sputter deposition as a tool for. There is no attempt to baffle or reduce the interactions between the target and microwave plasmas. In all types of ion sources, the gas ions are produced by various types of gas discharge including electron collisions with gas atoms. Hinson and h seigerman, the thin film book of basics, materials research corporation. The need for high enough freuqnecies is very nicely explained in this book. On icy moons, especially europa, sputtering of photolyzed water from the surface leads to net loss of hydrogen and accumulation of oxygenrich materials that may be important for life.
Equipment the rf sputtering system described by anderson, mayer and wehner2 is depicted in figure 3. This chapter contains a short discussion of some fundamental plasma phenomena. Oct 11, 2010 mntjs1600 single target plasma sputtering coater duration. Us5658442a target and dark space shield for a physical. Pdf fundamentals of plasma sputtering researchgate. The deposition technique used is called high power pulsed magnetron sputtering hppms. Sputter deposition an overview sciencedirect topics. Sputter deposition can be performed by energetic ion bombardment of a solid surface sputtering target in a vacuum using an ion gun or low pressure plasma space between the target and the substrate. This electric field accelerates the ar ions towards. A permanent magnet structure is located behind a target serving as a deposition source. High melting material or dielectrics with a high frequency generatorsource can be sputtered from a solid target. Treats glow discharge at several levels from basic phenomena to industrial applicationspractical techniques diligently related to fundamentals. To further reduce contaminant generation, the improved target is. Plasma confinement on the target surface is achieved by locating a permanent magnet structure behind the target surface.
Dc, pulsed dc, ac and rf power supplies may be used, depending upon target material, if reactive sputtering is desired and other factors. Apr 10, 2018 in the dark mode, drifting plasma current that causes sputtering, there is always the potential to spark. As the pressure increases for a particular sputtering power, the cds, ng are all compressed towards the cathode and a dark region is visible over the thin ng region till the substrateanode as shown in figure 1i,a for 0. Electric glow discharge is a type of plasma formed by passing a current at 100 v to several kv through a gas, usually argon or another noble gas. A plasma, at any given pressure, will find an equilibrium of electron generation and electron loss that defines the voltage versus current characteristic. In physics, sputtering is a phenomenon in which microscopic particles of a solid material are ejected from its surface, after the material is itself bombarded by energetic particles of a plasma or gas.
Sputter deposition is a physical vapor deposition pvd method of thin film deposition by sputtering. The sputter head and sputter power supply should be effective over a range of anticipated target materials. Argon plasma and excited copper atoms glow in a sputtering apparatus, which uses the plasma to blast atoms from a copper surface and allow them to coat a substrate. It occurs naturally in outer space, and can be an unwelcome source. The effect results in enhanced ion bombardment without the increase the operating pressure and sputtering rate for both dc and rf discharges. The critical process in a sputtering system occur in crookes dark space.
The purpose of this is to restrict ion bombardment and sputtering to the targets only. With the current increase in interest in controlled fusion and the wide spread use of plasma physics in space research and relativistic as trophysics, it makes sense for the study of plasmas to become a part of an undergraduate students basic experience, along. Particle contamination formation in magnetron sputtering. Ion mass, voltage difference and the thickness of the cathode dark space crookes transport through the plasma described by computational fluid dynamics deposition rate. The targets negative potential attracts positive ions from the plasma s edge. It is created by applying a voltage between two metal electrodes in a glass tube containing gas. To reduce particle deposition on the side wall of the target, the dark space shield has an inner surface 232 that is vertical, e. The microwave plasma envelops the annular space between the drum and the chamber.
It is found in products such as fluorescent lights and plasma screen televisions, and is used in plasma physics and analytical chemistry, and has been proposed as an alternative method by which stars produce their visible spectra. Dcmagnetron sputtering with an ag target on textile surfaces produced ag particles with sizes. The length of the cathode fall region or the dark space from the cathode to the. Analysis of the arc rate, particle defect density, and the intensity of the optical emission from the arcing plasma indicates that the critical aluminum oxide inclusion area for arcing is 0. The threshold sputtering time precluding airborne bacterial growth was about 60 s. With increasing current the cathode fall potential increases rapidly and the dark space shrinks. A plasma globe, illustrating some of the more complex plasma phenomena, including filamentation.
Sputtering is one of the forms of space weathering, a process that changes the physical and chemical properties of airless bodies, such as asteroids and the moon. The material sputtered or knocked off from the sputter target then impinges on and typically sticks to the substrate, usually a wafer. This doesnt mean reactive sputtering will give what one wants it is just one more thing to try with. Negative glow and faraday dark space 537 anode fall 537 other effects 538 sputtering and other con. In the dark mode, drifting plasma current that causes sputtering, there is always the potential to spark. At no point in the gap 126 should the spacing between the target and the dark space shield exceed 0. A scientific paper at the end of 2008 by caltech california institute of technology scientists upholds this view.
This technique has been used previously to demonstrate copper i and gold i laser action. Sputter removal of these features is inhibited by the dependence of sputter. Introduction to plasma physics new books in politics. Us52672a sputtering apparatus with a rotating target. Analysis of plasmainduced morphological changes in. The deposition rate is current dependant, and if we operate in the correct glow region of the characteristic plasma discharge, as previously described, several fold changes in current should be available for a relatively small change in. Bishop, in vacuum deposition onto webs, films and foils second edition, 2011. Develops detailed understanding of the deposition and etching of materials by sputtering discharge, and of etching of materials by chemically. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Ion and hall thrusters march 2008 the research described in this publication was carried out at the jet propulsion laboratory, california institute of technology, under a contract with the national aeronautics and space administration. It is often created by applying a voltage between two electrodes in a glass tube containing a lowpressure gas.
This is a relatively dark region on the anode side of the cathode glow that has a moderately strong electric field and a relatively high ion density. A glow discharge is a plasma formed by the passage of electric current through a gas. Manufacturers are careful to avoid this because it will flaw the finished surface. Otherwise, the target backing plate, mounting clips and mechanical. Hence, a chapter on sputter deposition in a book about thin films is quite relevant. This will result in an increased field across the dark space and in increased sputtering rates. Sputter deposition is a pvd method of depositing thin films by plasma sputtering. A simple calculation shows that frequencies in the low megacycle range are needed for good results2. The ag particle size did not vary significantly with. A plasma trail from the space shuttle atlantis during reentry into earths atmosphere, as seen from the international space station. Turning the plasma voltage far past normal limits leads to a runaway increase in plasma density and in atoms available for the substrate.
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