材料英语证书考试(PEC)-材料词汇解释.doc

材料英语证书考试(PEC)-材料词汇解释Acceptor- An impurity in a semiconductor which accepts electrons excited from the valence band, leading to hole conduction.Active Si layer- Silicon layer on top of the buried oxide (BOX) in SOI substrates.Adhesion- Ability of materials to stick (adhere) to each other.Adhesion layer- Material used to improve adhesion of materials, typically photo resist to the substrate in a photo lithographic processes. Some metals are also used to promote adhesion of subsequent layers.Amorphous Si, a-Si- Non-crystalline thin-film silicon having no long-range crystallography order; inferior electrical characteristics as compared to single-crystal and poly Si but cheaper and easier to manufacture; used primarily to fabricate solar cells.Angstrom, - Unit of length commonly used in semiconductor industry, though it is not recognized as a standard international unit; 1 = 10-8cm = 10-4 micrometer = 0.1 nm; the dimensions of a typical atoms.Anisotropic- Exhibiting physical properties in differing crystallography directions.Anisotropic Etch- A selective etch which exhibits an accelerated etch rate along specific crystallography directions.Batch process- Process in which many wafers are processed simultaneously, as opposed to a single wafer process.Bipolar- Semiconductor device fabrication technology which produces transistors that use both holes and electrons as charge carriers.Boat- 1. A device made of high purity temperature resistant materials such as fused silica, quartz, poly Si, or SiC designed to hold many semiconductor wafers during thermal or other processes; 2. device designed to simultaneously contain source material during evaporation while at the same time heating the source to its melting point; made of highly conductive, temperature-resistant material through which current is passed.Bonded SOI- SOI substrate formed by bonding two silicon wafers with oxidized surfaces such that one wafer is formed with an oxide layer sandwiched between two layers of Si; one wafer is subsequently polished down to a specified thickness to form an active layer where devices will be fabricated.Boron- Element from group III of the periodic table; acts as an acceptor in silicon; Boron is the only p-type dopant used in silicon device manufacturing.Bow- Concavity, curvature, or deformation of the wafer centerline independent of any thickness variation present.BOX-BuriedOxide in SOI substrates; the layer between wafers.Chemical Mechanical Polishing, CMP- A process for removal of surface material from the wafer which uses chemical and mechanical actions to achieve a mirror-like surface for subsequent processing.Chuck Mark- Any physical mark on either surface of a wafer caused by robotic end effecter, chuck, or wand.Clean Room- Enclosed ultra-clean space necessary for semiconductor manufacturing. Airborne particles are removed from the space to specified minimum levels, room temperature and humidity are strictly controlled; clean rooms are rated and range from Class 1 to Class 10,000. The number corresponds to the number of particles per cubic foot.Cleavage Plane- A crystallography preferred fracture plane.Compound Semiconductor- Synthetic semiconductor formed using two or more elements mainly from groups II through VI of the periodic table; compound semiconductors do not appear in natureConductivity- A measure of the ease with which charge carriers flow in a material; the reciprocal of resistivity.Crystal- Solid featuring periodic spatial arrangement of atoms throughout the entire piece of material.Crystal Defects- Departure from the ideal arrangement of atoms in a crystal.Czochralski Crystal Growth, CZ- Process utilizing crystal pulling to obtain single-crystal solids; the most common method for obtaining large diameter semiconductor wafers (e.g. 300mm Si wafers); desired conductivity type and doping level is accomplished by adding dopants to molten material. Wafers used in high-end Si microelectronics are almost uniquely CZ grown.Crystal Pulling- Process in which single-crystal seed is slowly withdrawn from the melt and material condenses at the liquid-solid interface gradually forming a rod-shaped piece of single-crystal material. Crystal pulling is the foundation of the Czochralski (CZ) single-crystal growth technique;D-defects- Very small voids in Si formed by agglomeration of vacancies.Denuded Zone- A very thin region on a semiconductor substrate surface cleared from contaminants and/or defects by gettering;Dicing- Process of cutting semiconductor wafer into individual chips each containing a complete semiconductor device. Large diameter wafer dicing is carried out by partially cutting the wafer along preferred crystallography planes using high precision saw with ultra-thin diamond blade.Die- A single piece of semiconductor containing entire integrated circuit which has not yet been packaged; a chip.Diffusion layer -A region of opposite conductivity type formed near the surface of a semiconductor crystal as a result of the introduction of impurities into the silicon crystal by means of solid state diffusion.Dimple- A shallow depression with gently sloping sides that exhibits a concave, spheroidal shape and is visible to the unaided eye under proper lighting conditions.Donor- An impurity or imperfection in a semiconductor which donates electrons to the conduction band, leading to electron conduction.Dopant- A chemical element, usually from the third or fifth columns of the periodic table,incorporated in trace amounts in a semiconductor crystal to establish its conductivity type and resistivity.Doping- Addition of specific impurities to a semiconductor to control the electrical resistivity.Elemental Semiconductor- A single element semiconductor from group IV of the periodic table; Si, Ge, C, Sn.EPI Layer- The term epitaxial comes from the Greek word meaning arranged upon. In semiconductor technology, it refers to the single crystalline structure of the film. The structure comes about when silicon atoms are deposited on a bare silicon wafer in a CVD reactor. When the chemical reactants are controlled and the system parameters are set correctly, the depositing atoms arrive at the wafer surface with sufficient energy to move around on the surface and orient themselves to the crystal arrangement of the wafer atoms. Thus an epitaxial film deposited on a oriented wafer will take on a orientation.Epitaxial Layer- A layer grown in the course of epitaxy.Epitaxy- A process by which a thin epitaxial layer of single-crystal material is deposited on single-crystal substrate; epitaxial growth occurs in such way that the crystallography structure of the substrate is reproduced in the growing material; also crystalline defects of the substrate are reproduced in the growing material. Although crystallography structure of the substrate is reproduced, doping levels and the conductivity type of an epitaxial layer is controlled independently of the substrate; e.g. the epitaxial layer can be made more pure chemically than the substrate.Etch- A solution, a mixture of solutions, or a mixture of gases that attacks the surfaces of a film or substrate, removing material either selectively or non-selectively.Evaporation- The common method used to deposit thin-film materials; material to be deposited is heated in a vacuum (10-6 - 10-7 Torr range) until it melts and starts evaporating; this vapor condenses on a cooler substrate inside the evaporation chamber forming very smooth and uniform thin films; not suitable for high melting point materials; PVD method of thin film formation.External, extrinsic gettering- The process in which gettering of contaminants and defects in a semiconductor wafer is accomplished by stressing its back surface (by inducing damage or depositing material featuring different than semiconductor thermal expansion coefficient)and then thermally treating the wafer; contaminants and/or defects are relocated toward back surface and away from the front surface where semiconductor devices can be formed.Flat- A portion of the periphery of a circular wafer that has been removed to a chord.Flatness- For wafer surfaces, the deviation of the front surface, expressed in TIR or maximum FPD, relative to a specified reference plane when the back surface of the wafer is ideally flat, as when pulled down by a vacuum onto an ideally clean, flat chuck.Float-zone Crystal Growth, FZ- The method used to form single crystal semiconductor substrates (alternative to CZ);poly crystalline material is converted into single-crystal by locally melting the plane where a single crystal seed is contacting the poly crystalline material; used to make very pure, high resistance Si wafers; does not allow as large wafers (n); electrons are majority carriers and dominate conductivity.Oxygen in silicon- Oxygen finds its way into silicon during the Czochralski single-crystal growth process; in moderate concentration (below 1017cm3) oxygen improves mechanical properties of a silicon wafer; excess oxygen acts as a n-type dopant in silicon.Particle- A small, discrete piece of foreign material or silicon not connected crystallography to the waferPhysical Vapor Deposition, PVD- Deposition of thin film occurs through physical transfer of material (e.g. thermal evaporation and sputtering) from the source to the substrate; the chemical composition of deposited material is not altered in the process.Planar Defect- Also known as area defect; basically an array of dislocations, e.g. grain boundaries, stacking faults.Point Defect- A localized crystal defect such as lattice vacancy, interstitial atom, or substitutional impurity. Contrast with light point defect.Polishing- Process applied to either reduce roughness of the wafer surface or to remove excess material from the surface; typically polishing is a mechanical-chemical process using chemically reactive slurry.Poly Crystalline Material, Poly- Many (often) small single-crystal regions are randomly connected to form a solid; size of regions varies depending on the material and the method of its formation. Heavily-doped poly Si is commonly used as a gate contact in silicon MOS and CMOS devices.Primary Flat- The flat of longest length on the wafer, oriented such that the chord is parallel with a specified low index crystal plane; major flat.Prime Grade- The highest grade of a silicon wafer. SEMI indicates the bulk, surface, and physical properties required to label silicon wafers as Prime Wafers. Used to manufacture devices, etc., best grade has tight mechanical and electrical properties.P-type Semiconductor- Semiconductor in which the concentration of holes is much higher than the concentration of electrons (np); holes are majority carriers and dominate conductivity.Quartz-Single-crystal SiO2.Reclaim Grade- A lower quality wafer that has been used in manufacturing and then reclaimed (etched or polished) and subsequently used again in manufacturing.Resistivity (electrical)- The measure of difficulty with which charged carriers flow through a material; the reciprocal of conductivity.RCA Clean -Is a standard set of wafer cleaning steps which needs to be performed before high temp processing steps (oxidation,diffusion,CVD) ofsilicon wafersinsemiconductormanufacturing. RCA cleaning includes RCA-1 and RCA-2 cleaning procedures. RCA-1 involves removal of organic contaminants, while RCA-2 involves removal of metallic contaminantsRoughness- The more narrowly spaced components of surface texture.Sapphire- Single-crystal Al2O3; can be synthesized and processed into various shapes; highly resistant chemically; transparent to UV radiation.SC1- 1stcleaning bath in standard RCA Clean sequence, NH4OH/H2O2/H2O solution designed to remove particles from Si surface.SC2- 2ndcleaning bath in standard RCA Clean sequence, HCl/H2O2/H2O solution designed to remove metals from the Si surface.Secondary Flat- A flat of length shorter than the primary orientation flat, whose position with respect to the primary orientation flat identifies the type and orientation of the wafer; minor flat.Seed Crystal- Single crystal material used in crystal growing to set a pattern for the growth of material in which this pattern is reproduced.Silicon- The most common semiconductor, atomic number 14, energy gap Eg=1.12 eV-indirect band gap; crystal structure-diamond, lattice constant 0.543 nm, atomic concentration 5x1022 atoms/cm, index of refraction 3.42, density2.33 g/cm3, dielectric constant 11.7, intrinsic carrier concentration