Edge Bead - during photoresist spin coating the photoresist layer is thicker at the edge of the wafer due to surface tension. The thicker area is referred to as the edge bead.
Edge Die - die in the edge exclusion area.
Edge Exclusion - an area at the edge of a wafer where die are absent or not used if present. Processes have an area at the edge of a wafer where the process does not conform to specification. In order to avoid shipping marginal die an edge exclusion is used.
EDODRAM - see Extended Data Out Dynamic Random Access Memory.
EEPROM - see, Electrically Erasable Programmable Read Only Memory.
Electrical Current - the flow of electrons.
Electrically Erasable Programmable Read Only Memory - a type of memory that may be electrically programmed to store data for later retrieval. EEPROMs are non volatile. EEPROMs may be electrically erased but all the data is erased at once.
Electrically Programmable Linear Array - a circuit made up of linear circuit elements which may be electrically programmed into a specific circuit configuration.
Electromagnetic Spectrum - the range of electromagnetic wave - wavelengths. There is no theoretical limit on the range of wavelengths in the electromagnetic spectrum.
Electromagnetic Waves - waves propagated through the simultaneous periodic intensity variation of an electric and magnetic fields. Electromagnetic waves propagate through free space without any medium. Electromagnetic waves include radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays and gamma rays.
Electromigration - the migration of atoms in a metal interconnect line due to momentum transfer from conduction electrons. The metal atoms migrate in the direction of current flow and can lead to failure of the metal Line. Electromigration depends on the metal in use with a fairly good correlation to the melting temperature of the metal, higher melting temperatures generally correspond to higher electromigration resistance, temperature, higher is worse, and current density, higher is worse. Electromigration may be due to diffusion in the bulk of the material, the grain boundaries or on the surface. Aluminum electromigration is primarily grain boundary due to the higher grain boundary diffusivity over the bulk diffusivity and the excellent surface Passivation effect of aluminum oxide that forms on the aluminum surface when exposed to oxygen. Copper on the other hand, has lower bulk and grain boundary electromigration and primarily exhibits electromigration on the surface due to poor copper oxide passivation properties.
Electron - a tiny subatomic particle carrying a negative charge equal to 1.602177 x 10-19 Coulombs. An electron is a fundamental unit of electronic charge.
Electron Beam - a focused stream of electrons.
Electron Beam Evaporation - the use of an electron beam to heat up a metal to perform evaporation.
Electron Beam Exposure - the use of an electron beam to write patterns into a photoresist film. A tightly focused electron beam is deflected by an electromagnetic field under computer control.
Electronic circuit - a collection of electronic elements that performs a prescribed function.
Ellipsometer - an optical measurement technique where a polarized laser beam is used to measure thickness and index of refraction for optically transparent films.
Emitter - the area of a bipolar transistor that emits carriers into the base region.
Emulsion Mask - a transparent glass plate with light blocking patterns formed on it by silver salts in suspension in a gelatin or colloidal. Emulsion masks are relatively low cost and were widely used when contact aligners were popular. The quality of emulsion masks is not sufficient for sub micron photolithography and their use largely faded away when projection aligners became popular.
Emitter Coupled Logic - a form of bipolar logic.
Energy - the capacity for doing work.
Energy Level - the allowable stable states of energy from quantum mechanical principles.
Enhancement Device - a MOSFET that is normally off until the channel region is "enhanced" with carriers.
EPAC - see, Electrically Programmable Linear Array.
Epi Layer - see, Epitaxial Layer.
Epitaxial Layer - a single crystal layer formed on top of a single crystal substrate. An epitaxial layer will typically have a different doping level and or type than the substrate upon which the epitaxial layer is formed. In some cases the epitaxial layer may be a completely different type of material than the substrate upon which it is grown. If the substrate and the epitaxial layer are both the same element or compound then the process is homoepitaxy and if the epitaxial layer and the substrate are different elements or compounds then the process if hetroepitaxy. see also, crystalline.
EPROM - see Erasable Programmable Read Only Memory.
Erasable Programmable Read Only Memory - a type of memory that may be electrically programmed to store data and erased by exposure to ultraviolet light. EPROM's are non volatile and can only be erased by shining a strong ultraviolet light through a window in the device package. During erasure all data is erased at once.
Etching - the process of removing a material by chemical reaction.
Ethylene Glycol - chemical formula HOCH2CH2OH, ethylene glycol is used as an etch activity reducer. Ethylene glycol has a density of 1.11Kg/L. Ethylene glycol is hazardous if ingested.
EUV - see Extreme Ultraviolet
Evaporation - a process technology where metal to be deposited on a wafer is heated in a vacuum chamber to it's melting point and the vapor from the metal condenses onto wafers forming a thin film.
Evaporator - a piece of semiconductor equipment used to perform evaporation.
Excimer Laser - The term excimer comes from the combination of excited and dimer. The excimer laser was developed in the late seventies and has output in the ultraviolet and near ultraviolet region. In an excimer laser a noble gas such as krypton, Kr, or xenon, Xe, is excited in the presence of a halogen such as fluorine, F, or chlorine, Cl, and neon, Ne, or helium, He, in a resonant cavity. A high voltage pulse dissociates electrons from the noble gas molecules creating a plasma. In the excited state, noble gas atoms combine with the halogen atoms forming a metastable compound such as KrF or ArF with a lifetime of several nanoseconds. When the electrons in the outer shell of the excited compound are stimulated to a lower energy level, ultraviolet light is emitted and the metastable compound disassociates in a few femtoseconds into the original elements.
Exponential Model - a probability model for converting defect density to projected die yield based on the exponential distribution.
Exposed - an area of photoresist that has had radiation interact with it during an exposure process.
Exposure - the process of allowing radiation to interact with some areas of a photoresist layer while blocking the radiation from reaching other areas of photoresist.
Extended Data Out Dynamic Random Access Memory - a type of DRAM with higher data throughput than standard RAM. EDODRAM has now been largely replaced by higher throughput synchronous DRAM.
Extreme Ultraviolet - an electromagnetic wave with a wavelength of 10 to 100 nanometers. Extreme ultraviolet commonly refers to a wavelength of 13 nanometers used for exposure. Extreme ultraviolet wavelength based aligners are a candidate to replace optical lithography for <70 nanometer linewidth photolithography.
