Thin-film deposition is any technique for depositing a thin film of material onto a substrate or onto previously deposited layers. "Thin" is a relative term, but most deposition techniques allow layer thickness to be controlled within a few hundred nanometers, and some allow one layer of atoms to be deposited at a time. Deposition is a word used in many fields to describe different processes: In law, deposition is the taking of testimony outside of court. ... A nanometre (American spelling: nanometer) is 1. ... Molecular beam epitaxy, also called MBE, is the deposition of one or more pure materials onto a single crystal wafer, one layer of atoms at a time, under ultra-high vacuum, forming a perfect crystal. ...

It is useful in the manufacture of optics (for reflective or anti-reflective coatings, for instance), electronics (layers of insulators, semiconductors, and conductors form integrated circuits), and packaging (i.e., aluminum-coated mylar). Similar processes are sometimes used where thickness is not important: for instance, the purification of copper by electroplating, and the deposition of silicon and enriched Uranium by a CVD-like process after gas-phase processing. See also list of optical topics. ... The term reflection (also spelt reflexion) can refer to several different concepts: In mathematics, reflection is the transformation of a space. ... Anti-reflective coatings are applied to lenses and other devices to reduce reflection from optical surfaces. ... Two digital voltmeters The field of electronics is the study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ... Insulators are materials which prevent the flow of heat (thermal insulators) or electric charge (electrical insulators). ... A semiconductor is a material with an electrical conductance that is intermediate to those of an insulator and a conductor. ... It has been suggested that Conductor (power engineering) be merged into this article or section. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... Packaging is the enclosing of a physical object, typically a product that will be offered for sale. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2. ... Mylar is a trade name of DuPont Teijin Films of Hopewell, VA for biaxially-oriented polyethylene terephthalate (BOPET) polyester film used for its high tensile strength, chemical and dimensional stability, transparency, and electrical insulation. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance copper, metallic Atomic mass 63. ... Electroplating is the coating of an electrically conductive item with a layer of metal using electrical current. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery gray metallic Atomic mass 238. ... CVD can refer to: Chemical vapor deposition Center for Voting and Democracy This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Deposition techniques fall into two broad categories, based on whether they are understood in terms of chemistry, or of physics. Chemistry (in Greek: χημεία) is the science of matter and its interactions with energy and itself (see physics, biology). ... When stuff moves. ...

Chemical deposition

Here, a fluid precursor undergoes a chemical change at a solid surface, leaving a solid layer. An everyday example is the formation of soot on a cool object when it is placed inside a flame. Since the fluid surrounds the solid object, deposition happens on every surface, with little regard to direction; thin films from chemical deposition techniques tend to be conformal, rather than directional. // General In generic terms, a precursor is something that existed before and was incorporated into something that came later. ...

Chemical deposition is further categorized by the phase of the precursor:

• Plating relies on liquid precursors, often a solution of water with a salt of the metal to be deposited. Some plating processes are driven entirely by reagents in the solution (usually for noble metals), but by far the most commercially important process is electroplating. It was not commonly used in semiconductor processing for many years, but has seen a resurgence with more widespread use of Chemical-mechanical polishing techniques.

• Chemical vapor deposition (CVD) generally uses a gas-phase precursor, often a halide or hydride of the element to be deposited. In the case of MOCVD, an organometallic gas is used. Commercial techniques often use very low pressures of precursor gas.

• Plasma enhanced CVD uses an ionized vapor, or plasma, as a precursor. Unlike the soot example above, commercial PECVD relies on electromagnetic means (electric current, microwave excitation), rather than a chemical reaction, to produce a plasma.

This article is about the industrial process. ... In chemistry, salt is a general term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. ... A reagent is any substance used in a chemical reaction. ... Noble can refer to a member of the nobility a Noble gas or Noble is a British automobile manufacturer. ... Electroplating is the coating of an electrically conductive item with a layer of metal using electrical current. ... Chemical-mechanical planarization or Chemical-mechanical polishing, commonly abbreviated CMP, is a technique used in semiconductor fabrication for planarizing the top surface of an in-process semiconductor wafer or other substrate. ... Chemical vapor deposition (CVD) is a chemical process for depositing thin films of various materials. ... A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. ... A hydride is a chemical compound of a hydrogen with other elements. ... Organometallic have classically been compounds having bonds between one or more metal atoms and one or more carbon atoms of an organyl group. ... The word plasma has a Greek root which means to be formed or molded (the word plastic shares this root). ... This page is about the radiation; for the appliance, see microwave oven. ...

Physical deposition

Physical deposition uses mechanical or thermodynamic means to produce a thin film of solid. An everyday example is the formation of frost. Since most engineering materials are held together by relatively high energies, and chemical reactions are not used to store these energies, commercial physical deposition systems tend to require a low-pressure vapor environment to function properly; most can be classified as physical vapor deposition. Blades of grass coated in frost. ...

The material to be deposited is placed in an energetic, entropic environment, so that particles of material escape its surface. Facing this source is a cooler surface which draws energy from these particles as they arrive, allowing them to form a solid layer. The whole system is kept in a vacuum deposition chamber, to allow the particles to travel as freely as possible. Since particles tend to follow a straight path, films deposited by physical means are commonly directional, rather than conformal. Energy is a fundamental quantity that every physical system possesses; it allows us to predict how much work the system could be made to do, or how much heat it can produce or absorb. ... The thermodynamic entropy S, often simply called the entropy in the context of thermodynamics, is a measure of the amount of energy in a physical system that cannot be used to do work. ...

Some examples of physical deposition are given below:

• A thermal evaporator uses an electric heater to boil the material. This is done in a high vacuum, both to prevent the gas from reacting with or scattering against atoms in the chamber, and to lower the material's boiling point. Obviously, only materials with a much lower vapor pressure than the heating element can be deposited without contamination of the film.

• An electron beam evaporator fires a high-energy beam from an electron gun to boil a small spot of material; since the heating is not uniform, higher vapor pressure materials can be deposited.

• Sputtering relies on a plasma (usually a noble gas, such as Argon) to knock material from a "target" a few atoms at a time. The target can be kept at a relatively low temperature, since the process is not one of evaporation, making this one of the most flexible deposition techniques. It is especially useful for compounds or mixtures, where different components would otherwise tend to evaporate at different rates.

• Pulsed laser deposition systems work by an ablation process. Pulses of focused laser light to transform the target material directly from solid to plasma; this plasma usually reverts to a gas before it reaches the substrate.

In particle physics, scattering is a class of phenomena by which particles are deflected by collisions with other particles. ... The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid. ... The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ... A heating element converts electricity into heat through the process of Joule heating. ... An electron gun is a component that produces an electron stream that has a precise kinetic energy, being used in all TVs and monitors which use cathode ray tube technology. ... The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ... Sputtering is a physical process whereby atoms in a solid target material are ejected into the gas phase due to bombardment of the material by energetic ions. ... The word plasma has a Greek root which means to be formed or molded (the word plastic shares this root). ... The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... Pulsed laser deposition is a thin film deposition technique. ... Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. ... Laser (US Air Force) A LASER (Light Amplification by Stimulated Emission of Radiation) is an optical device which uses a quantum mechanical effect called stimulated emission (discovered by Einstein while researching the photoelectric effect) in order to generate a coherent beam of light from a lasing medium of controlled purity...

Other deposition processes

Some methods fall outside these two categories, relying on a mixture of chemical and physical means:

• In reactive sputtering, a small amount of some non-noble gas such as oxygen or nitrogen is mixed with the plasma-forming gas. After the material is sputtered from the target, it reacts with this gas, so that the deposited film is a different material, i.e. an oxide or nitride of the target material.

• In Molecular beam epitaxy (MBE), slow streams of an element can be directed at the substrate, so that material deposits one atomic layer at a time. Compounds such as gallium arsenide are usually deposited by repeatedly applying a layer of one element (i.e., Ga), then a layer of the other (i.e., As), so that the process is chemical, as well as physical.

Sputtering is a physical process whereby atoms in a solid target material are ejected into the gas phase due to bombardment of the material by energetic ions. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Molecular beam epitaxy, also called MBE, is the deposition of one or more pure materials onto a single crystal wafer, one layer of atoms at a time, under ultra-high vacuum, forming a perfect crystal. ... This article is about the chemical compound. ... General Name, Symbol, Number gallium, Ga, 31 Chemical series poor metals Group, Period, Block 13, 4, p Appearance silvery white   Atomic mass 69. ... as, As or AS may stand for: // as A conjunction or preposition in the English language with various meanings. ...

See also

• Materials science
• Photolithography
• MEMS
• CVD, MBE, and Sputtering

The Materials Science Tetrahedron Materials science is a multidisciplinary field focusing on functional solids, whether the function served is structural, electronic, thermal, chemical, magnetic, optical, or some combination of these. ... Photolithography is a process used in semiconductor device fabrication is to transfer a pattern from a photomask (also called reticle) to the surface of a wafer or substrate. ... Micro Electro-Mechanical Systems (MEMS) is the technology of the very small, yet not within the realm of Molecular nanotechnology. ... CVD can refer to: Chemical vapor deposition Center for Voting and Democracy This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Molecular beam epitaxy, also called MBE, is the deposition of one or more pure materials onto a single crystal wafer, one layer of atoms at a time, under ultra-high vacuum, forming a perfect crystal. ... Sputtering is a physical process whereby atoms in a solid target material are ejected into the gas phase due to bombardment of the material by energetic ions. ...

External links

(A Google search on "thin film deposition" leads to 25,000 links, mostly for related equipment, textbooks, and university courses; very little of a tutorial or explanatory nature)

• University of Wisconsin: Laboratory for Thin Film Deposition
• Cambridge University Facilities
• Thin Film Deposition Processes and Techniques (A textbook summary and order form)
• ORNL (Oak Ridge National Laboratory)
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