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. It occurs naturally in outer space, and can be an unwelcome source of wear in precision components. However, the fact that it can be made to act on extremely fine layers of material is utilised in science and industry—there, it is used to perform precise etching, carry out analytical techniques, and deposit thin film layers in the manufacture of optical coatings, semiconductor devices and nanotechnology products. It is a physical vapor deposition technique.
A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage. It represents a local region where the air has undergone electrical breakdown and become conductive, allowing charge to continuously leak off the conductor into the air. A corona discharge occurs at locations where the strength of the electric field around a conductor exceeds the dielectric strength of the air. It is often seen as a bluish glow in the air adjacent to pointed metal conductors carrying high voltages, and emits light by the same mechanism as a gas discharge lamp.
A flashtube (flashlamp) is an electric arc lamp designed to produce extremely intense, incoherent, full-spectrum white light for a very short time. A flashtube is a glass tube with an electrode at each end and is filled with a gas that, when triggered, ionizes and conducts a high-voltage pulse to make light. Flashtubes are used most in photography; they also are used in science, medicine, industry, and entertainment.
An inductively coupled plasma (ICP) or transformer coupled plasma (TCP) is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields.
A glow discharge is a plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a value called the striking voltage, the gas ionization becomes self-sustaining, and the tube glows with a colored light. The color depends on the gas used.
The induction lamp, electrodeless lamp, or electrodeless induction lamp is a gas-discharge lamp in which an electric or magnetic field transfers the power required to generate light from outside the lamp envelope to the gas inside. This is in contrast to a typical gas discharge lamp that uses internal electrodes connected to the power supply by conductors that pass through the lamp envelope. Eliminating the internal electrodes provides two advantages:
Corona treatment is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. The corona plasma is generated by the application of high voltage to an electrode that has a sharp tip. The plasma forms at the tip. A linear array of electrodes is often used to create a curtain of corona plasma. Materials such as plastics, cloth, or paper may be passed through the corona plasma curtain in order to change the surface energy of the material. All materials have an inherent surface energy. Surface treatment systems are available for virtually any surface format including dimensional objects, sheets and roll goods that are handled in a web format. Corona treatment is a widely used surface treatment method in the plastic film, extrusion, and converting industries.
A capacitively coupled plasma (CCP) is one of the most common types of industrial plasma sources. It essentially consists of two metal electrodes separated by a small distance, placed in a reactor. The gas pressure in the reactor can be lower than atmosphere or it can be atmospheric.
The electrodeless plasma thruster is a spacecraft propulsion engine commercialized under the acronym "E-IMPAcT" for "Electrodeless-Ionization Magnetized Ponderomotive Acceleration Thruster". It was created by Mr. Gregory Emsellem based on technology developed by French Atomic Energy Commission scientist Dr Richard Geller and Dr. Terenzio Consoli, for high speed plasma beam production.
Plasma activation is a method of surface modification employing plasma processing, which improves surface adhesion properties of many materials including metals, glass, ceramics, a broad range of polymers and textiles and even natural materials such as wood and seeds. Plasma functionalization also refers to the introduction of functional groups on the surface of exposed materials. It is widely used in industrial processes to prepare surfaces for bonding, gluing, coating and painting. Plasma processing achieves this effect through a combination of reduction of metal oxides, ultra-fine surface cleaning from organic contaminants, modification of the surface topography and deposition of functional chemical groups. Importantly, the plasma activation can be performed at atmospheric pressure using air or typical industrial gases including hydrogen, nitrogen and oxygen. Thus, the surface functionalization is achieved without expensive vacuum equipment or wet chemistry, which positively affects its costs, safety and environmental impact. Fast processing speeds further facilitate numerous industrial applications.
Plasma-enhanced chemical vapor deposition (PECVD) is a chemical vapor deposition process used to deposit thin films from a gas state (vapor) to a solid state on a substrate. Chemical reactions are involved in the process, which occur after creation of a plasma of the reacting gases. The plasma is generally created by radio frequency (RF) frequency or direct current (DC) discharge between two electrodes, the space between which is filled with the reacting gases.
Sputter deposition is a physical vapor deposition (PVD) method of thin film deposition by the phenomenon of sputtering. This involves ejecting material from a "target" that is a source onto a "substrate" such as a silicon wafer. Resputtering is re-emission of the deposited material during the deposition process by ion or atom bombardment. Sputtered atoms ejected from the target have a wide energy distribution, typically up to tens of eV. The sputtered ions can ballistically fly from the target in straight lines and impact energetically on the substrates or vacuum chamber. Alternatively, at higher gas pressures, the ions collide with the gas atoms that act as a moderator and move diffusively, reaching the substrates or vacuum chamber wall and condensing after undergoing a random walk. The entire range from high-energy ballistic impact to low-energy thermalized motion is accessible by changing the background gas pressure. The sputtering gas is often an inert gas such as argon. For efficient momentum transfer, the atomic weight of the sputtering gas should be close to the atomic weight of the target, so for sputtering light elements neon is preferable, while for heavy elements krypton or xenon are used. Reactive gases can also be used to sputter compounds. The compound can be formed on the target surface, in-flight or on the substrate depending on the process parameters. The availability of many parameters that control sputter deposition make it a complex process, but also allow experts a large degree of control over the growth and microstructure of the film.
High-power impulse magnetron sputtering is a method for physical vapor deposition of thin films which is based on magnetron sputter deposition. HIPIMS utilises extremely high power densities of the order of kW⋅cm−2 in short pulses (impulses) of tens of microseconds at low duty cycle of < 10%. Distinguishing features of HIPIMS are a high degree of ionisation of the sputtered metal and a high rate of molecular gas dissociation which result in high density of deposited films. The ionization and dissociation degree increase according to the peak cathode power. The limit is determined by the transition of the discharge from glow to arc phase. The peak power and the duty cycle are selected so as to maintain an average cathode power similar to conventional sputtering (1–10 W⋅cm−2).
Plasma-immersion ion implantation (PIII) or pulsed-plasma doping is a surface modification technique of extracting the accelerated ions from the plasma by applying a high voltage pulsed DC or pure DC power supply and targeting them into a suitable substrate or electrode with a semiconductor wafer placed over it, so as to implant it with suitable dopants. The electrode is a cathode for an electropositive plasma, while it is an anode for an electronegative plasma. Plasma can be generated in a suitably designed vacuum chamber with the help of various plasma sources such as electron cyclotron resonance plasma source which yields plasma with the highest ion density and lowest contamination level, helicon plasma source, capacitively coupled plasma source, inductively coupled plasma source, DC glow discharge and metal vapor arc. The vacuum chamber can be of two types - diode and triode type depending upon whether the power supply is applied to the substrate as in the former case or to the perforated grid as in the latter.
A microplasma is a plasma of small dimensions, ranging from tens to thousands of micrometers. Microplasmas can be generated at a variety of temperatures and pressures, existing as either thermal or non-thermal plasmas. Non-thermal microplasmas that can maintain their state at standard temperatures and pressures are readily available and accessible to scientists as they can be easily sustained and manipulated under standard conditions. Therefore, they can be employed for commercial, industrial, and medical applications, giving rise to the evolving field of microplasmas.
Plasma is one of four fundamental states of matter, characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, being mostly associated with stars, including the Sun. Extending to the rarefied intracluster medium and possibly to intergalactic regions, plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field.
Plasma polymerization uses plasma sources to generate a gas discharge that provides energy to activate or fragment gaseous or liquid monomer, often containing a vinyl group, in order to initiate polymerization. Polymers formed from this technique are generally highly branched and highly cross-linked, and adhere to solid surfaces well. The biggest advantage to this process is that polymers can be directly attached to a desired surface while the chains are growing, which reduces steps necessary for other coating processes such as grafting. This is very useful for pinhole-free coatings of 100 picometers to 1 micrometre thickness with solvent insoluble polymers.
Plasma-activated bonding is a derivative, directed to lower processing temperatures for direct bonding with hydrophilic surfaces. The main requirements for lowering temperatures of direct bonding are the use of materials melting at low temperatures and with different coefficients of thermal expansion (CTE).
Piezoelectric direct discharge (PDD) plasma is a type of cold non-equilibrium plasma, generated by a direct gas discharge of a high voltage piezoelectric transformer. It can be ignited in air or other gases in a wide range of pressures, including atmospheric. Due to the compactness and the efficiency of the piezoelectric transformer, this method of plasma generation is particularly compact, efficient and cheap. It enables a wide spectrum of industrial, medical and consumer applications.
Glow-discharge optical emission spectroscopy (GDOES) is a spectroscopic method for the quantitative analysis of metals and other non-metallic solids. The idea was published and patented in 1968 by Werner Grimm from Hanau, Germany.
