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Vacuum
An absence of air or other gas.
Vacuum decay method
Leakage detection determined by the loss vacuum (increase in pressure), over a period of time within a vessel or piping system.
Vacuum valve
A shutoff valve that, when open, connects the system to a pressure less than atmospheric pressure.
Value-added operation
Any operation required to meet the final performance criteria for the product, assuming every step is run optimally and without delays between operations.
Valve seat
The internal sealing area of a valve, either seat or interference fit valve design.
Vapor
The gaseous form of substances that are normally in the solid or liquid state, and that can be changed to these states either by increasing the pressure or decreasing the temperature.
Vapor density
The weight of a vapor or gas compared to the weight of an equal volume of air.
Vapor pressure
The pressure exerted when a solid or liquid is in equilibrium with its own vapor.¢?簾岬? Vapor pressure is a function of the substance and of the temperature.
Variables
Those characteristics of a part or process that can be measured.¢?簾岬? Examples are thickness in angstroms, step height in ¡×¡ⓒ, and haze in parts per million.¢?簾岬? Variables are measured on a continuous scale.
Verification run
Any unit or units (product or nonproduct) processed by the equipment to establish that it is performing its intended function within specifications.
Very large scale integration
The placement of between 1,000 and 1,000,000 components on a die.
VHSIC
Very High Speed Integrate Circuits. The acronym applied to the Department of Defense sponsored research and development program to advance the state of the art in semiconductor device speeds, densities, power consumption, and system effectiveness.
Via
An opening in the dielectric layer(s) through which a riser passes, or in which the walls are made conductive; an area that provides an electrical pathway from one metal layer to the metal layer above or below.
Virtual design
An approach to designing a product whereby the entire process is completed on a computer without the actual implementation in silicon.Design trade-off and implementation decisions, as well as verification exercises, occur entirely with the help of software tools. Only after all specifications are met and the designer is satisfied with the result does the actual implementation take place.
Virtual factory
A rapid prototyping software environment for factory design and manufacturing engineering based on computer simulations at various levels, such as process, device, circuit, equipment, and line.
Virtual semiconductor device
A virtual control computer in s SECS message service/open systems interconnection network environment for the control of semiconductor equipment. Any number of virtual semiconductor devices may reside in a single physical computer system. Also called virtual device.
Virtual tracking unit
An object or group of objects, such as a number of substrates or an individual die or mask group, that the factory floor control system treats as a single entity for purposes of tracking.
Viscosity
Measurement of the flow properties of a material expressed as its resistance to flow.
VLSI
Very Large Scale Integrated Circuits. VLSI devices are generally accepted to be those that contain more than 1000 gate equivalents, but less than 10,000.
Retry count
In the block transfer protocol, the number of unsuccessful attempts to send a block. Also see block, block transfer protocol, and RTY.
Critical temperature
The temperature above which gas cannot be liquefied by pressure alone.
Rework
Material rejected the first time through ; sent back through the production area in an effort to cull or current the defect and use the material.
Provability of failure
see fault probability.
Photophobia
abnormal sensitivity to light, especially by the eyes.