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Wafer
in semiconductor technology, a thin slice with parallel faces cut from a semiconductor crystal. Also called a slice. Also see substrate.
Wafer bumping
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.
Wafer carrier
1: any vessel or supporting structure used to contain or transfer wafers during processing. 2: a device for holding a wafer for various processing steps in semiconductor manufacturing. Also see carrier, quartz carrier, and transfer carrier.
Wafer environment
the atmosphere contained within a chamber in which the wafers are exposed.
Wafer flat
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.
Wafer height
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.
Wafer interface line
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.
Wafer interface plane
in wafer transport equipment, the static height of the physical wafer support at the input and output ports, regardless of the processing height.
Wafer plane (Wp)
in multiple wafer carriers, the position of the wafer within a carrier.
Wafer plane offset
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.
Wafer Process Chamber (WPC)
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.
Wafer sort
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.
Wafer support platform
a slot, pedestal, or set of pins used to hold a wafer in a horizontal attitude.
Wafer tilt
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.
Wafer transfer
the act of relocating wafers from one carrier into another.
Wafer Transfer Chamber (WTC)
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.
Wafer transfer step
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.
Wafer transport axis
the center line of transport module end effector motion. This center line is symmetric with the wafer transport zone.
Wafer transport plane
in modular equipment, the horizontal surface that a wafer traverses between modules. Also see cluster tool.
Wafer transport position
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.
Wafer transport zone
in modular equipment, the area of the interface plane that is free of physical obstructions and reserved for wafer movement between modules. Also see cluster tool.
Wafer, calibration
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.
Wafer, control
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.
Wafer, dummy
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. Also called filler wafer.
Wafer, monitor
a wafer used to assess a unit process concurrent with product wafers. Also see wafer, test.
Wafer, reclaim
a silicon wafer that has been processed, then stripped, sometimes polished, and then cleaned; can be reprocessed for a different use.
Wafer, reclaim test
a silicon wafer that has been subjected to semiconductor manufacturing and subsequently restored to a condition suitable for use in process monitoring. Contrast wafer, virgin test.
Wafer, test
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. 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.
Wafer, virgin test
a silicon slice that has not been used in semiconductor manufacturing and is suitable for use in process monitoring. Contrast wafer, reclaim test.
Wafer-level reliability
a methodology to assess the reliability impact of tools and processes by testing mechanism-specific test structures under accelerated conditions during device processing.
Wafer's seated surface
of a wafer in a multiple wafer carrier, the surface closest to the bar end of the carrier, regardless of the carrier's orientation.
Wafers, horizontal
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. Also called horizontal orientation.
Wafers, vertical
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. Also called vertical orientation.
Warm-up time
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.
Warp
of a free, unclamped semiconductor wafer, the difference between the maximum and minimum distances of the median surface from a reference plane.
Warp factor
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.
WAT
Wafer Acceptance Test. See wafer.
Water bath
a bath of vigorously boiling water.
Water reactive
describes a material that reacts with water to release a gas that is either flammable or that presents a health hazard.
Watt (W)
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.
Wave soldering
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.
Wavelength
The color of light. A rule of thumb is that one must use a wavelength of light that is close to or smaller than the size of the feature one is trying to create in a photolithography process. Visible light (the rainbow) runs from wavelengths of about 0.4 microns (violet) to nearly 0.8 microns (red). The violet G-line wavelength of a mercury lamp is 0.44 microns and is used in photolithography for 0.65 micron semiconductor technologies and above. The ultra-violet I-line of a mercury lamp (0.36 microns) is currently used for 0.5 and 0.35 micron processes. To move to the 0.25 and 0.18 micron geometries of the next generation of semiconductors it will be necessary to move to a different light source - the excimer laser - with wavelengths in the deep ultra-violet range (0.25 microns for a krypton fluoride laser and 0.19 microns for an argon fluoride laser).
Waves
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.
Waviness
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.
Wax residue
a film of wax that migrated onto a wafer surface from (any of) several possible sources.
W-bit (wait-bit)
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.
Wedge
see taper.
Weld splatter
in metal lid/preform assembly, melted preform material that extends from the weld.
Well
a localized n-type region on a p-type wafer or a p-type region on an n-type wafer.
Wet chemical etch
a physical etch process that uses chemicals such as hydrofluoric acid to remove unprotected areas of a wafer layer.
Wet cleaning
Cleaning of wafers by immersing them in chemicals such as acids. This can be done in sinks, spray tools (machines that work like dishwashers) or spin tools (machines that work like laundry machines).
Wet etching
Etching away of layers on a wafer by immersion in a chemical bath.
Wetted surface
1: surface that contacts the fluid. 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.
Whirler
see coater.
White arsenic
see arsenic trioxide.
Window
any dielectric opening in an insulating wafer that allows electrical connection between lower and upper layers. Also see contact and via.
window frame
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.
Window frame
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.
WIP
see work-in-progress (WIP) inventory.
WIP
see work-in-progress (WIP) inventory.
Wire bonding
The most common method of making the electrical inter- connection from the chip to the leads on a package There are three basic methods: thermal compression, ultrasonic, and pulse. The wires are typically made of either aluminum or gold and are usually 1.25 to 1.50 mils in diameter for ICs but can be as large as 15 mils in diameter for power devices. See mil.
wire bonding (W/B)
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.
Wire Bonding (W/B)
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.
Wire-connected interface
a parallel input/output interface connected by means of wire and connector.
wire-connected interface
a parallel input/output interface connected by means of wire and connector.
WLR
Wafer Level Reliability. See wafer.
wood alcohol
see methanol.
Wood alcohol
see methanol.
Working distance
in scanning electron microscopy, the distance between the bottom of the objective lens and the sample.
working distance
in scanning electron microscopy, the distance between the bottom of the objective lens and the sample.
work-in-progress (WIP) inventory
inventory, either inactive or being processed, that has been started into manufacturing but has not been completed.
Work-In-Progress (WIP) inventory
inventory, either inactive or being processed, that has been started into manufacturing but has not been completed.
WorkStream
a factory floor management and automation system used to control the tracking of material in the factory, including wafers, equipment, and work instructions. Formerly called COMETS.
WorkStream
a factory floor management and automation system used to control the tracking of material in the factory, including wafers, equipment, and work instructions. Formerly called COMETS.
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