Self-aligned gateIn semiconductor electronics fabrication technology, a self-aligned gate is a transistor manufacturing approach whereby the gate electrode of a MOSFET (metal–oxide–semiconductor field-effect transistor) is used as a mask for the doping of the source and drain regions. This technique ensures that the gate is naturally and precisely aligned to the edges of the source and drain. The use of self-aligned gates in MOS transistors is one of the key innovations that led to the large increase in computing power in the 1970s.
Thin filmA thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many applications. A familiar example is the household mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface. The process of silvering was once commonly used to produce mirrors, while more recently the metal layer is deposited using techniques such as sputtering.
Silicon tetrachlorideSilicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colorless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. It is a part of the chlorosilane family. Silicon tetrachloride is prepared by the chlorination of various silicon compounds such as ferrosilicon, silicon carbide, or mixtures of silicon dioxide and carbon. The ferrosilicon route is most common.
OxideAn oxide (ˈɒksaɪd) is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of –2) of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of (called a passivation layer) that protects the foil from further oxidation.
HydrideIn chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids.
Radical polymerizationIn polymer chemistry, free-radical polymerization (FRP) is a method of polymerization by which a polymer forms by the successive addition of free-radical building blocks (repeat units). Free radicals can be formed by a number of different mechanisms, usually involving separate initiator molecules. Following its generation, the initiating free radical adds (nonradical) monomer units, thereby growing the polymer chain. Free-radical polymerization is a key synthesis route for obtaining a wide variety of different polymers and materials composites.
Reactive oxygen speciesIn chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species: O2{} + e^- -> \ ^\bullet O2- Dismutation of superoxide produces hydrogen peroxide (): 2 H+{} + 2 \ ^\bullet O2^-{} -> H2O2{} + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water: H2O2{} + e^- -> HO^-{} + \ ^\bullet OH 2 H+ + 2 e- + H2O2 -> 2 H2O In a biological context, ROS are byproducts of the normal metabolism of oxygen.
Group 14 hydrideGroup 14 hydrides are chemical compounds composed of hydrogen atoms and group 14 atoms (the elements of group 14 are carbon, silicon, germanium, tin, lead and flerovium). The tetrahydride series has the chemical formula , with X representing any of the carbon family. Methane is commonly the result of the decomposition of organic matter and is a greenhouse gas. The other hydrides are generally unstable, poisonous metal hydrides. They take on a pyramidal structure, and as such are not polar molecules like the other p-block hydrides.
Polycyclic aromatic hydrocarbonA polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. PAHs are uncharged, non-polar and planar. Many are colorless. Many of them are found in coal and in oil deposits, and are also produced by the incomplete combustion of organic matter—for example, in engines and incinerators or when biomass burns in forest fires.
Failure of electronic componentsElectronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits. Failures most commonly occur near the beginning and near the ending of the lifetime of the parts, resulting in the bathtub curve graph of failure rates.
