SEMATECH Dictionary of Semiconductor Terms

A-Am | An-Az | B | C-Ch | Ci-Com | Con-Cz | D-De | Df-Dz | E-En | Eo-Ez | F-Fl
Fm-Fz | G | H | I | J-K | L | M-Mes | Met-Mz | N | O | P-Ph | Pi-Pq | Pr-Pz | Q | R
S-Se | Sh-So | Sp-Sta | Ste-Sz | T-Th | Ti-Tz | U-V | W-Z

"W, X, Y, & Z "

wafer n		in semiconductor technology, a thin slice with parallel faces cut from a semiconductor crystal. [ASTM F1241] Also called a slice. Also see substrate.
wafer bumping n		the process by which contact points on a wafer are heightened above the wafer surface by adding conductor material. These contact bumps are bonded or fused to make all required electrical connections to tape, packages, or other interconnection substrates in a single process step. Bumps may be provided on the die edges or distributed over the surface of the die in an area array. [1994 National Technology Roadmap for Semiconductors]
wafer, calibration n		a wafer with a known distribution of simulated particles to be used for sizing (for example, polystyrene latex spheres) in terms of diameter in micrometers or a known number of simulated particles to be used for counting accuracy and location information (for example, etch pits) on the wafer surface. [SEMATECH]
wafer carrier n		1 : any vessel or supporting structure used to contain or transfer wafers during processing. [SEMATECH] 2 : a device for holding a wafer for various processing steps in semiconductor manufacturing. [SEMI E1-86] Also see carrier, quartz carrier, and transfer carrier.
wafer, control n		a wafer that is allowed to pass entirely through a tool, being subject to a mechanical characterization without being subject to the actual process conditions. [SEMATECH]
wafer, dummy n		a noncritical wafer added to a load-sensitive operation or run to complete a load of the equipment or process. Dummy wafers are never measured. [SEMATECH] Also called filler wafer.
wafer environment n		the atmosphere contained within a chamber in which the wafers are exposed. [SEMATECH]
wafer flat n		straight cuts on the side of a wafer; used to indicate the type of free-carrier conduction and orientation of the crystal surface. Also used to align the wafer during processing and scribing. [SEMATECH]
wafer height n		in quartz and high-temperature wafer carriers, the distance from the horizontal center line of a wafer to the bottom plane of the wafer carrier. [SEMI E2-86]
wafer interface line n		in wafer transport equipment, the intersection of a side that contains a port (or an extension from such a side) and the wafer interface plane. An extension from a side is in 75-mm (approximately 2.95 in) multiples and applies to the distance between the front and rear wafer interface lines and to the center lines of input and output ports. [Adapted from SEMI E8-92]
wafer interface plane n		in wafer transport equipment, the static height of the physical wafer support at the input and output ports, regardless of the processing height. [SEMI E8-92]
wafer-level reliability n		a methodology to assess the reliability impact of tools and processes by testing mechanism-specific test structures under accelerated conditions during device processing. [SEMATECH]
wafer, monitor n		a wafer used to assess a unit process concurrent with product wafers. [SEMATECH] Also see wafer, test.
wafer plane (Wp) n		in multiple wafer carriers, the position of the wafer within a carrier. [SEMI E1.9-94]
wafer plane offset n		in a wafer carrier pocket, the distance from the pocket center plane to the center of the wafer zone. The offset from the pocket center plane toward datum A is a negative value. [SEMI E1.9-94]
wafer process chamber (WPC) n		the chamber(s) within the process equipment in which wafers are processed. A process chamber interfaces with any or all of the cleanroom interface chambers, wafer treatment chambers, and pre- or post-process treatment chambers. [SEMATECH]
wafers, horizontal n		that orientation of a wafer carrier in which the wafers in the wafer carrier are horizontal, with their finished side normally up. This orientation implies that the crossbar end of the wafer carrier is down. [SEMI E11-89] Also called horizontal orientation.
wafer, reclaim n		a silicon wafer that has been processed, then stripped, sometimes polished, and then cleaned; can be reprocessed for a different use. [SEMATECH]
wafer, reclaim test n		a silicon wafer that has been subjected to semiconductor manufacturing and subsequently restored to a condition suitable for use in process monitoring. [SEMI M8-84] Contrast wafer, virgin test.
wafer's seated surface n		of a wafer in a multiple wafer carrier, the surface closest to the bar end of the carrier, regardless of the carrier's orientation. [Adapted from SEMI E1.9-94]
wafer sort n		the process after wafer fabrication during which the electrical parameters of integrated circuits are tested for functionality. Probes contact the pads of the circuit to conduct the test. [1994 National Technology Roadmap for Semiconductors]
wafer support platform n		a slot, pedestal, or set of pins used to hold a wafer in a horizontal attitude. [SEMI E22-91]
wafers, vertical n		that orientation of a wafer carrier in which the wafers are vertical, or standing on edge. This orientation implies that the bottom of the wafer carrier is down. [SEMI E11-89] Also called vertical orientation.
wafer, test n		1 : a wafer that is exposed to all of the conditions of process characterization, including, but not limited to, actual etch conditions or actual film deposition conditions. [SEMATECH] Also called monitor wafer. 2 : a silicon wafer suitable for process monitoring during semiconductor manufacturing. The two types are the reclaim test wafer and the virgin test wafer. [SEMI M8-84]
wafer transfer chamber (WTC) n		the chamber(s) within the process equipment in which wafers are transferred either from a cleanroom interface chamber or load lock to any process or pre-/post-process treatment chamber. The WTC may also be a chamber used for temporary wafer staging or storage. No wafer processing is performed within the WTC. [SEMATECH]
wafer tilt n		in plastic and metal wafer carriers, the possible unparallel position of a wafer in relation to the crossbar end of a wafer carrier when the wafer carrier is resting on the crossbar end. [SEMI E1-86]
wafer transfer n		the act of relocating wafers from one carrier into another. [SEMI E1-86]
wafer transfer step n		in cluster tools, a sequence of micro moves that form part of a point-to-point wafer transfer and that, from the point of view of the particular port resource, may proceed from start to finish without interruption. [SEMATECH]
wafer transport axis n		the center line of transport module end effector motion. This center line is symmetric with the wafer transport zone. [SEMI E22-91]
wafer transport plane n		in modular equipment, the horizontal surface that a wafer traverses between modules. [SEMI E21-94] Also see cluster tool.
wafer transport position n		a location within a process or cassette module where the wafer is accepted or presented by the transport module end effector. This is also the location of the wafer centroid. [SEMI E22-91]
wafer transport zone n		in modular equipment, the area of the interface plane that is free of physical obstructions and reserved for wafer movement between modules. [SEMI E21-94] Also see cluster tool.
wafer, virgin test n		a silicon slice that has not been used in semiconductor manufacturing and is suitable for use in process monitoring. [SEMI M8-93] Contrast wafer, reclaim test.
warm-up time n		in mass flow devices, the time required, after going from an unpowered to a powered state, for the device to achieve sufficient electrical and thermal stability such that rated performance specifications can be met. [SEMI E29-93]
warp n		of a free, unclamped semiconductor wafer, the difference between the maximum and minimum distances of the median surface from a reference plane. [ASTM F1241]
warp factor n		a measure of the warpage of a plastic semiconductor package. Warp factor is defined as total warp in millimeters (inches) divided by package dimension in millimeters (inches), expressed as a percentage. [SEMATECH]
water bath n (process chemicals)		a bath of vigorously boiling water. [Adapted from SEMI C1-94]
water reactive adj		describes a material that reacts with water to release a gas that is either flammable or that presents a health hazard. [SEMI S4-92]
watt (W) n		a measurement unit for electrical power. One volt of electrical potential difference causing one ampere of electrical current to flow will produce one watt of power. [SEMATECH]
waves n		in the manufacture of silicon wafers, uneven contours in the surface of a wafer that are visible to the unaided eye under large-area diffuse illumination. [SEMI M1-94 and ASTM F1241]
wave soldering n		a technique for solder application and reflow in which a wave of liquid solder is directed onto the underside of a printed circuit board to solder the components. [SEMATECH]
waviness n		the more widely spaced component of surface texture. DISCUSSION-Waviness may be caused by such factors as machine or work piece deflections, vibration, and chatter. Roughness may be considered as superimposed on a wavy surface. [ASTM F1241]
wax residue n		a film of wax that migrated onto a wafer surface from (any of) several possible sources. [ASTM F1241]
W-bit (wait-bit) n		in a header for message transfer, a bit indicating that the sender of a primary message expects a reply. NOTE-A value of one in the W-bit means that reply is expected. A value of zero in the W-bit means that no reply is expected. The W-bit must be set to zero in all secondary messages. [SEMI E4-91]
wedge		see taper.
weld splatter n		in metal lid/preform assembly, melted preform material that extends from the weld. [SEMI G53-92]
well n		a localized n-type region on a p-type wafer or a p-type region on an n-type wafer. [SEMATECH]
wet chemical etch n		a physical etch process that uses chemicals such as hydrofluoric acid to remove unprotected areas of a wafer layer. [SEMATECH]
wetted surface n		1 : surface that contacts the fluid. [SEMI F4-90] 2 : in a fluid distribution system component, any internal surface that will come into contact with the process media contained by the component during normal operation. [SEMATECH]
whirler		see coater.
white arsenic		see arsenic trioxide.
window n		any dielectric opening in an insulating wafer that allows electrical connection between lower and upper layers. [SEMATECH] Also see contact and v ia.
window frame n		a pressed ceramic layer, generally in the shape of a window frame, that is used to create an extra layer on top of the leads of a cerdip or cerpack package. It is attached to the leads by a devitrifying solder glass. A cap or cover may be similarly sealed to the window frame. [SEMI G33-90]
WIP		see work-in-progress (WIP) inventory.
wire bonding (W/B) n		the most common method of making an electrical connection from a die to a substrate. The wire is bonded to the die and substrate by using thermal compression and/or ultrasonic welding. Wires are typically made of aluminum or gold. [SEMATECH]
wire-connected interface n		a parallel input/output interface connected by means of wire and connector. [SEMI E23-91]
wood alcohol		see methanol.
working distance n		in scanning electron microscopy, the distance between the bottom of the objective lens and the sample. [SEMATECH]
work-in-progress (WIP) inventory n		inventory, either inactive or being processed, that has been started into manufacturing but has not been completed. [SEMATECH]
WorkStream n		a factory floor management and automation system used to control the tracking of material in the factory, including wafers, equipment, and work instructions. [SEMATECH] Formerly called COMETS.
X-direction		see scan direction.
XLS		see extended light scatterer.
-MR(mean-moving range) control chart n		a chart that tracks the difference between a current measurement and the value of the previous measurement. [SEMATECH]
X-ray fluorescence n		1 : the property of atoms to absorb X rays and emit light of characteristic wavelengths. [SEMATECH] 2 : a material diagnostic technique that determines the surface concentration of contaminants. [SEMATECH]
X-ray lithography n		the use of X rays to transfer integrated circuit patterns from masks or reticles to resist-coated wafers. [SEMATECH]
X terminal n		a graphics workstation or specialized graphics terminal that runs an X Window System manager, such as the Motif Window Manager, as its only active process. An application running on another computer communicates with the X terminal according to X Window System protocol. [SEMATECH]
X Windows n		a suite of specifications for standardized graphics programming; the software technology that supports the windowing environment on most workstation-class computers It is based on X11, originally developed by the Massachusetts Institute of Technology (MIT) and Digital Equipment Corporation. [SEMATECH]
X-X axis n		the horizontal axis, or axis in the left-to-right direction, in a plane Cartesian coordinate system along which a row of functional patterns is nominally disposed by stepping and repeating. [ASTM F127-84 and SEMI D4-94]
xylene n		any one of a family of poisonous, flammable, and colorless hydrocarbon liquids derived from coal tar, wood tar, and petroleum. These liquids are isomeric (contain the same chemical components, but have differing physical and chemical properties because of the arrangement of the molecules). [SEMI C1.21-90]
Y-direction n		in characterizing surface roughness, the direction over which successive scans are taken by a microscope, orthogonal to the scan direction, in the sample plane. [SEMATECH]
Y-Y axis n		the vertical axis orthogonal to the X-X axis in a plane Cartesian coordinate system along which a column of functional patterns is nominally disposed by stepping and repeating. [ASTM F127-84 and SEMI D4-94]
yield n		the percentage of wafers or die produced in an operation or process that conform to specifications. [SEMATECH]
yield model n		a mathematical model that estimates defect limited yields and assists failure analysis characterization by relating integrated circuit yield to circuit and process parameters. [SEMATECH]
Z-direction n		in characterizing surface roughness, the direction perpendicular to the sample plane, orthogonal to the X and Y directions. [SEMATECH] Also called feature height direction.
"zee" purge n		a configuration of purging manifold, similar to the"cross" purge, in which the purge gas inlet valve is connected to an inlet port of a three-ported, two-way regulator isolation valve. [SEMI Chemicals/Gases, Vol. 1, 1990 (no longer in print)]
zero dislocations n		a single-crystal semiconductor with a dislocation density of fewer than 500 dislocations per square centimeter. [SEMI Materials, Vol. 3, Definitions for Semiconductor Materials] Also called zero and zero D.
zero effect n		in flat panel displays, the change in zero due to a change in ambient temperature from one normal operating temperature to a second normal operating temperature. All other conditions must be held within the limits of reference operating conditions. [SEMI E18-91]
zero gas n		in determining contaminant contribution by gas distribution system components, a purified gas that has an impurity concentration below the minimum detection limit (MDL) of the analytical instrument. This gas is used for both instrument calibration and component testing. [SEMATECH]
zeolite n		a group of white or colorless (sometimes red or yellow) hydrous tectosilicate minerals characterized by an aluminosilicate tetrahedral framework, ion-exchangeable large cations, and loosely held water molecules permitting reversible dehydration. [SEMATECH]
Z-plane n		in measuring semiconductor leadframes for characteristics such as lead and die pad planarity, the reference Z-plane is defined as the average of the height of the two dambars when measured at their geometric center, given that the dambars do not differ in location by more than 0.003 in. [SEMI G9-89]

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