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An equivalent oxide thickness usually given in
nanometer 330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...
s (nm) is the thickness of
silicon oxide Silicon oxide may refer to either of the following: *Silicon dioxide or quartz, SiO2, very well characterized *Silicon monoxide Silicon monoxide is the chemical compound with the formula SiO where silicon is present in the oxidation state +2. In ...
film that provides the same electrical performance as that of a high-κ material being used. The term is often used when describing field effect transistors, which rely on an electrically insulating pad of material between a
gate A gate or gateway is a point of entry to or from a space enclosed by walls. The word derived from old Norse "gat" meaning road or path; But other terms include ''yett and port''. The concept originally referred to the gap or hole in the wall ...
and a doped
semiconducting A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
region. Device performance has typically been improved by reducing the thickness of a silicon oxide insulating pad. As the thickness of the insulating pad approached 5–10 nm, leakage current became a problem and alternate materials were necessary. These new materials had a lower equivalent oxide thickness so they could retain an appropriate gate oxide thickness to prevent leakage current while also increasing the switching speed. For example, a high-κ material with
dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulat ...
of 39 (compared to 3.9 for silicon oxide) would be ten times thicker than that of silicon oxide, helping to reduce the leakage of electrons across the dielectric pad, while achieving the same
capacitance Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...
and high performance. In other words
silicon oxide Silicon oxide may refer to either of the following: *Silicon dioxide or quartz, SiO2, very well characterized *Silicon monoxide Silicon monoxide is the chemical compound with the formula SiO where silicon is present in the oxidation state +2. In ...
film of one-tenth the thickness of the high-κ film would be required to achieve similar performance while ignoring leakage current. Commonly used high-κ gate dielectrics include
hafnium oxide Hafnium(IV) oxide is the inorganic compound with the formula . Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. H ...
and more recently aluminum oxide for gate-all-around devices. :\mathrm = t_\text \left( \frac\right) The EOT definition is useful to quickly compare different
dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...
materials to the industry standard silicon oxide dielectric, as: :\epsilon_0\, \epsilon_ \frac = \epsilon_0 \, \epsilon_\text \, \frac = C Semiconductors {{electronics-stub