Absorption

To take up a substance into or throughout a material or fabric by physical or chemical means. A particular piece of protective clothing may act more like a sponge and absorb certain liquids rather than act active barrier.

Ambient temperature

The temperature of the environment (air) around a suite, object or individual.

Analog integrated circuit

A type of integrated circuit in which the signals are continuous and can take on any value within a range, instead of just one of two possible values (digital). Analog chips are often used for applications like multimedia and communications. Testing of analog chips must be done on a test designed to be able to handle analog signals.

ASTM F1001

Standard chemical test battery used to compare material resistance across like chemicals. Currently consists of 15 liquids and 6 gases with each chemical representing a different family of chemicals.

ASTM F1052

Standard practice for pressure testing of “Level A” totally encapsulating chemical protective suits. Test if suit has “air leaks” which could possibly allow entry of hazardous substances.

ASTM F739

Standard test method for resistance of protective clothing materials to permeation. Fives consistent and repeatable method to determine if material “X” provides sufficient barrier to chemical “Y”.

ASTM

American Society for Testing and Materials – Guidelines for safety and standardization of manufactured goods. Organized into 140 committees. Co F23 is made up of individuals representing both producers and users of protective clothing. The group develops test methods and voluntary standards assessing the performance of protective clothing against occupational hazards.

Atomic force microscope (AFM)

A microscope that works by bringing a fine needle right up to the surface of a semiconductor and tracing the topography of the material. AFM’s are an alternative to scanning electron microscopes as a means of measuring and monitoring the widths and heights of critical geometries (critical dimensions – CDs) on a circuit.

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Back end manufacturing

The portion of semiconductor manufacturing that happens after the wafer has left the cleanroom. This includes testing the chips at wafer level, repairing the chips if necessary, dicing the wafers and putting the individual chips into packages. In short, back end manufacturing is test and assembly. There is a growing trend among semiconductor manufacturers to outsource the assembly, and often the testing too, to independent assembly houses.

Back grind

Thinning the wafers just before dicing them up in the packaging process by grinding away at the reverse side of the wafer on a grinding wheel. Wafers must be a certain minimum thickness during processing or they will break too easily. If the chips are too thick they become difficult to package.

Binning

Classifying chips by their performance (usually speed) – the analogy is to physically drop things into different bins. This happens at the final test. Once the chops have been packaged, they are tested one more time to see if they work and how well they perform.

Body Box Test

This is a test to determine how particle shed a garment has. During the body box test, a subject is placed in a Class 10 room and performs a series of activities during a 10 minute test period. The activities include arm extensions for 3 minutes, walking for 3 minutes and doing 5 deep knee bends in 1 minute. These activities are separated by 1 minute intervals of standing still. The data is reported as the average number of particles .5 micron and larger counted per minute during the 10 minute test period.

Boiling Point

The temperature at which a liquid turns to gas in standard atmospheric pressure. For example, the boiling point of water at sea level is 100°C, 212°F.

Bootie

A sock-like extension of the suit leg designed to protect the wearer’s feet. Allows the wearer to use his own boots while ensuring the chemical protection provided by the primary suit material.

Bound seam

A clean-finished binding that encapsulates the raw edges of two plies of fabric. All layers are sewn through with a chain stitch.

Breakthrough time

The time that elapses between the time the challenge chemical first contacts the test specimen (e.g. suit fabric) and the time at which the chemical is detected on the collection side of the permeation cell. Basically, how long dies the suit material “X” holds out challenge chemical “Y”? This is determined by permeation testing. Also referred to as “Chemical Detection Time”.

Butyl

Synthetic or man-made rubber. Invented during the 1950’s for use in everything from car tires to chemical warfare suits. Considered a durable fabric, it has good barrier to a limited number of chemicals.

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Challenge agent

The chemical or mixture to which a material is exposed. Also called “attacking chemical”.

Chemical Mechanical Polishing (CMP)

Polishing the top surface of a wafer aided by a slurry containing abrasive grit suspended in reactive chemical agents. As the name implies, the polishing action is partly mechanical and partly chemical.

Chemical Vapor Deposition (CVD)

Deposition of thin films (usually dielectrics or insulators) on silicon wafers by placing the wafers in a mixture of gases that react at the surface of the wafers.

Cleanroom

The facility in which semiconductor manufacturers process their wafers. Dust and particles that might fall on the wafers during processing and result is not working are kept out of the cleanroom by filtering the air and managing the airflow. Humans are required to wear specially designed cleanroom apparel over their street clothes, and must put on gloves and face masks.

Cm2

Square centimeter. Measure of area about equal to the size of a standard shirt button.

Composite (Films/Materials)

Refers to materials constructed with two or more layers of dissimilar (different) materials. Generally exhibit broad chemical resistance. Adding more layers increases the barrier protection of chemical protective clothing.

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Damascene process

A way of making metal lines which involves depositing an insulator (oxide), etching a trench in the oxide, depositing metal everywhere and then polishing back with CMP so there is just metal left in the trench. This is the opposite of the traditional sequence that has metal being deposited first, the metal being patterned through etching, and the oxide being deposited to try to fill the gaps between the metal.

Degradation

Refers to the loss of integrity of a material when attacked by a chemical. When a glove is dipped into a chemical, does it change color, wrinkle, fall apart, or show other signs of attack? Test are usually based on weight gain over a period of time, in other words, has material absorbed chemical? Does not indicate if gases passed through material (permeation).

Dice

Semiconductor chips. Plural of die.

Dicing

Cutting up the wafer into individual chips. This is usually done with a circular saw called a dicing saw.

Die

The term for a single semiconductor chip. Strictly speaking, the plural of die is dice, though engineers have a tendency to use the term die both in singular and the plural.

Die attach

Attaching a die to its mount in its package. This is often done with a metal-based glue-like silver epoxy for good conduction of heat way from the chip. Chips get hot when they are running in normal operation, so packages must be designed to help dissipate the heat.

Dielectric

See insulator.

Digital

A type of circuit in which the signals can have only one of the two possible states (an “I” or an “O”). This is in contrast to analog circuits in which the signals are continuous and can take on any value within a range.

Doffing

Taking off a protective suit.

Donning

Putting on a protective suit.

Dopant

Tiny amounts of impurities can change the electronic properties of the silicon, affecting greatly how it conducts electric current. Selected impurities called dopants are deliberately introduced into the silicon to create devices such as transistors.

Dry etching

Another name for plasma etching.

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Elastomeric

“Rubber” based materials; e.g. Butyl, Neoprene, and Viton. Typically durable but have limited chemical resistance.

Elongation

Stretching without breaking. One of the physical properties used to compare fabrics.

Encapsulation

Encasing the die in plastic as part of the packaging process. This is done after the die has been attached to its lead by clamping a mold around the die and injecting molten plastic into the cavity of the mold

Endothermic (Reactions)

A process or chemical reaction that is characterized by the absorption of heat.

Epitaxy

The deposition of a thin film of silicon on a silicon wafer, in such a way that the deposited layer forms a single continuous crystal with the underlying wafer. This method is used to create a high quality, low doped surface in which to make transistors and other devices on top of a highly doped substrate with a low electrical resistance.

Evaporation

The changing of a liquid to a gaseous state. See also: Boiling Point, Sublimation, and Vapor Pressure.

Exothermal (Reactions)

A process or chemical reaction that is characterized by release of heat, for example, combustion reactions.

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F.E.P.

Fluorinated ethylenepropylene – type of material commonly known as Teflon® – used in clear form as an overlay for chemical suit visors, to provide extra chemical protection. (Also known as Fluoroethylene Polymer).

Fab

Short for wafer fabrication facility - a semiconductor factory. Often used to refer to a semiconductor cleanroom.

Field

Since a photolithographic stepper cannot accurately deal with imaging the microscopic circuit features over all of a wafer at one time, it exposes an area it can easily manage. This is called a field. The stepper will keep moving the wafer and exposing a new area the size of a field till the whole wafer is done (about 80 fields on an 8-inch wafer).

Film (products/fabrics)

Usually refers to materials composed of multiple layers. Such products generally are less durable, but present a wider range of chemical holdout than elastomeric fabrics.

Flame resistant

Material that inherently resists ignition (burning), melting or other degradation when exposed to heat or flame.

Flame retardant

Material that is typically treated to extinguish itself upon ignition from a flame source.

Flexural Fatigue Test

Physical test used to measure the durability of a suit material. NFPA test consists of twisting a fabric many times.

Flow rate

The rate at which a quantity of fluid or gas passes a given point, expressed as volume over time (ft3/min, cm2/min).

Footprint

The area a machine takes up in the cleanroom. This is important because cleanroom space is expensive, and so minimizing the footprint of a machine is a good thing to do. There are two numbers that semiconductor manufacturers are interested in – the footprint and the linear frontage number (length of the front of the machine). The linear frontage number w many machines will fit into a bay since the machines are all lined up side by side.

Front-end manufacturing

This refers to wafer processing that takes place in the cleanroom, as opposed to processing that happens after the wafer has been essentially finished. Once the wafer is done with its cleanroom processing, it moves into the back end manufacturing which involves test and assembly (packaging). There is potential for confusion with this terminology because semiconductor engineers also divide the front end manufacturing into two parts, called front end processing and back end processing. Front end processing is the device formation part, and the back end processing (in the wafer fab) is the part in which all the interconnect wires of the integrated circuit are laid down and defined.

Furnace

A long glass (quartz) tube that can be heated to high temperatures. Furnaces are used for giving wafers heat treatments, oxidizing them, or reacting gases in the vicinity of the wafers to result in the deposition of thin films on the wafers (CVD). Furnaces used to be horizontal (long direction parallel to the floor) but current generation ones built for eight inch wafers are mostly vertical (tubes standing upright).

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Gas

One of the three physical states (gas/solid/liquid) in which a chemical or substance can appear. This state is characterized by very low density. The gas phase of a substance is dependent on temperature and pressure. Many chemicals appear commercially in liquid and gas state, and require different levels of protection accordingly.

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Hazardous chemical

Any substance that can cause physical harm.

Helmke Drum Test

A test for measuring particle shedding of a suit used for cleanroom applications. The suit is tumbled for 10 minutes at 10 revolutions per minute in a stainless steel drum having an enclosed volume of 1 cubic foot to determine the average rate of release of particles 0.3 microns and larger. An automatic particle counter is used to sample the air at the rate of one cubic foot per minute during the ten minute test period. The particle counts are then summarized.

High k e dielectric

An insulator which will not conduct electricity but which when sandwiched between metal plates will easily allow these plates to talk to each other via electric fields (this is called a capacitor structure). While high k dielectrics are good for capacitors, the opposite is true of the insulators used to separate metal lines, for which low k dielectrics are desirable.

High-Density Plasma (HDP)

Plasma that contains a high concentration of reactive elements. High-density plasmas are used in advanced plasma etchers and CVD machines.

High-Density Plasma CVD (HDPCVD)

A chemical vapor deposition technique in which a concentrated plasma is created. This suppresses the bulging at outside corners that standard CVD films tend to show. HDPCVD is thus a good solution to the problem of getting insulating films to fill in between narrowly spaced metal lines (the gap fill problem). Gap fill is becoming more and more of an issue as semiconductor manufacturers scale down circuit dimensions.

High-Density Plasma Etcher

An advanced etcher that uses high-density plasma. This results in a better capability for etching small geometries with straight vertical walls (especially difficult for small deep holes) and good selectivity (etching only the layer to be patterned and not attacking the layer beneath.)

Hook and loop

Fastening technique for storm flap closures. Common trade name is Velcro

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Inches of water (or cm of water)

A measure of pressure.

Inking

The process of marking bad dice on a wafer with dots of ink so that these dice will be discarded without the expense of putting them in packages.

Integrated circuit

A complete electronic circuit with transistors and wires connecting these transistors on a semiconductor chip.

Inter Bay Automation

Automated transport of wafers throughout the entire fab, between the machine bays. One way of doing this is with an overhead monorail system.

Interconnect

Wires patterned in integrated circuits to connect different devices together.

Intra Bay Automation

Automated transport of wafers within a bay of machines. There are a number of products that are used for this, as machine interfaces are not yet standardized. Mobile robots that run on rails, or are free standing, can be used. Another option is to extend a brand off a central inter bay overhead

Ion implantation

The process by which dopants are introduced in exact quantities into silicon. A stream of charged particles (called ions) or phosphorus, arsenic, or boron is created and then directed at a silicon wafer at a precisely controlled velocity (energy). In this way both the concentration and depth of the dopant can be controlled.

Insulator

A material that will not allow an electric current to flow through it. In everyday life, we cover electric wires and plugs with rubber or plastic, which are insulators, so that we do not get electric shocks. In semiconductor chips, commonly used insulators are silicon dioxide (glass) and silicon nitride (silicon+nitrogen). Semiconductor engineers more often refer to these materials as dielectrics.

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Lead

A name for the metal prongs which stick out of a chip package, allowing electrical connection between the chip inside the package and the outside world.

Lead frame

A spider-like frame of wires that the chip will be connected to. The lead frame is bent to form the metal pins that run out of the semiconductor package. This allows the packaged chip to be plugged into its electrical socket so that it can function.

Liquid

A substance that, unlike a solid, flows readily, but unlike a gas, does not tend to expand indefinitely. Important to know state of chemicals – gas, liquid, or solid – when determining type of protective clothing necessary.

Logic Chip

A chip that does computations, makes decisions, or makes things happen. Chips can be loosely defined as either logic chips or memory chips.

Low k dielectric

A type of insulator that isolates metal connections, preventing these from interfering with each other. Metals that are close together can affect each other’s signals through the electric fields that run between them.

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Mask

Sometimes called photomask or reticle.

Masking layer

A patterned layer associated with a semiconductor integrated circuit. A typical circuit will require between 12 and 25 masking layers for full definition.

MDL

Minimum Detection Limit. See System Detection Limit.

Memory Chip

A chip that retains information for logic chips to use.

Micron

One thousand microns make one millimeter. A human hair is about 100 microns thick. A transistor in an advanced semiconductor process might have an area of about 4 microns by 1.5 microns (though of course transistors vary greatly in size depending on their purpose.

MIL

Unit of length or thickness. 1/1000 (.001) of an inch.

Mullen Burst Test

A physical property test for material strength. Represents the force that would be applied when a bending elbow bursts through a shirt sleeve.

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Neoprene

Natural rubber, non-synthetic. A durable elastomeric material with moderate chemical resistance.

NFPA 1991

Performance standard for vapor protective clothing.

NFPA 1993

Performance standard for disposable protective garments used in decontamination procedures.

NFPA

National Fire Protection Association.

NIOSH

(National Institute for Occupational Safety and Health) – A regulatory or respiratory protection; technical advisement for OSHA.

Non-conductive

A property of an object, substance or material which restricts or prevents the flow of electricity.

Non-volatile memory

Semiconductor memory that will not forget its data once the power is switched off. This is in contrast to volatile memory that loses information when there is no power supplied to the chip.

NFPA 1992

Performance standard for splash protective garments.

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Oxidation

The oxidation process is used to insulate. Silicon can be oxidized to become silicon dioxide by raising it to high temperatures (about 900 degrees centigrade or above) in an oxygen environment. Silicon dioxide is an insulator, and so is used in semiconductor circuits to isolate different conducting regions.

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Pass Through

A bulkhead coupling system or chamber that allows materials to be passed between the cleanroom and a corridor without causing contamination.

Penetration

Visible physical entry of a chemical in liquid form through an opening such as a seam, zipper, or similar area. Not on a molecular level as with permeation.

Permeation rate

The rate at which permeation occurs. Commonly expressed a micrograms per square centimeter per minute (µg/m2/min).

Permeation

Refers to the passage of a chemical through a protective clothing material on a molecular level. Gases may be passing through the material leaving no detectable physical signs of damage to the clothing. Unlike degradation, testing for permeation involves elaborate gas detection instruments. It is the highest level of testing available for protective clothing fabrics.

Photolithography

The photographic process used to transfer circuit patterns onto a semiconductor wafer. This is done by projecting light through a patterned reticle, onto a silicon wafer covered with a photosensitive material (photoresist). A reticle is a glass plate with a layer of chrome on one side.

Photoresist

Sometimes referred to as resist. This is a photosensitive material that will dissolve in developer if it has been exposed to light. Patterns are transferred to a wafer by covering the wafer with photoresist, exposing a pattern in the photoresist and then using the patterned photoresist as a mask through which to implant dopants or etch the material.

Physical Vapor Deposition (PVD)

Deposition of thin films by physical means as opposed to chemical means. This is most often used for deposition of metals. The most common firm of PVD is sputtering, in which a metal target is exposed to a plasma gas like argon which is not chemically reactive. The excited gas atoms hit the target and knock off metal atoms that deposit onto a wafer place below, building up the desired metal film.

Planarization

Flattening the surface of the wafer. Both the devices and the metal wires used in the circuits have height. Several layers have to be built up, one on top of another, to make a complete circuit. It is difficult to create the lithography and etching layers if the surface of the wafer is not flat. Thus, every so often process steps must be added in to flatten the surface of the wafer. This is called planarization, and in modern advanced processes it is often down with chemical mechanical polishing (CMP).

Plasma

A highly excited gas. Plasmas are created by exposing gases at low pressure to an electric or electromagnetic field. In semiconductor processing, plasmas are used for etching and thin film deposition (the excited state of the gas makes it very reactive).

Plasma Ashing

A variant of plasma etching, used specifically for removal of photoresist. A plasma of oxygen ions is created and these ions react with the oxygen and carbon which make up photoresist to create water vapor and carbon dioxide. The photoresist is thus burned away or ashed, not so much because of high temperature, like in a fire, but because the oxygen is made particularly reactive when it becomes a charged ion in the plasma.

Plasma Enhanced Chemical Vapor Deposition (PECVD)

Chemical vapor deposition in which a plasma is created from the reactant gases. The ions in the plasma are in an excited state and so will easily react with the silicon wafer, without the need for elevated temperatures as in conventional (thermal) CVD.

Plasma Etching

Also called dry etching. This involves using plasma gas to etch a semiconductor layer. Plasma contains highly excited molecules (reactive ions) that easily react chemically. There is also a physical bombardment mechanism in that the ions are accelerated towards the wafer with an electric field. Plasma etching is usually anisotropic, which means that the etching takes place in only in one direction (line of sight). This is a key advantage over wet etching with chemicals.

Platform

The frame of the machine, including robotic handling apparatus, needed to feed wafers from their loading station into the individual process modules in which the processing will occur. Cluster tools are machines in which more than one process chamber is mounted on the platform, so that several wafers can be processed at a time (with identical or different processes).

Polymer

A general term used to define chemical compounds such as polyethylene or polypropylene. Technically they are long chains of molecular bonded repeating structural units of the original molecules.

Polysilicon

Silicon that is deposited on wafers in a form that is crystalline, but is not one continuous crystal like the silicon wafers are. Polysilicon is used as a critical part of a transistor called the transistor gate. It is also sometimes used as a resistor, and as a wire for connecting things together (although it does not conduct electricity as well as the metal wires used in integrated circuits).

PPM

Parts Per Million. A typical example of part per million is one second in 11 days.

Pressure Testing

Standard test used is ASTM Method F1052. Tests for leaks that would compromise the vapor protection of a chemical suit.

Primary Suit Material

The material that is used for the main body parts of a garment.

Prober

A machine for aligning contacting pins (probe cards) to the dice (chips) on a wafer, so that these chips can be electrically tested even before they are packaged and connected to standardized metal leads. This is termed wafer level probing.

PVC

Poly Vinyl Chloride. A durable thermoplastic material with a variety of uses from floor tiles to protective clothing fabric and face shields (visors). Good durability but has limited range of chemical protection. Typically used for protection against acids.

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Radiant heat

The energy given off (for example from a flash fire) in the form of infrared radiation, like that from a heat lamp.

Rapid thermal processing (RTP)

A method of rapidly heating up a wafer by exposing it to bright lamps. Wafers can be raised from room temperature to up to 1100 degrees centigrade in seconds, and cooled in a similar length of time.

Reagent grade

The highest concentration of a chemical commercially available. Typically greater than 95% concentration.

Reduction stepper

A photolithography machine that reduces the image that is projected onto the wafer. The typical reduction factor is 5x, which makes the process easier for the reticle makers since they can make the features on the reticles five times larger than what is needed on the circuit.

Resist

A common term for photoresist.

Resist track

Sometimes called a track. A common name for a photoresist spin coater. The term “track” comes from the early designs in which wafers were transported to and from the spin stations on parallel rails called tracks. These days the more advanced spin coaters use robotic arms for movement of the wafers.

Reticle

Sometimes called a mask or a photomask. This is a glass plate with chrome on one side in which a pattern is etched. The pattern is transferred to the wafer by shining light through the reticle. A typical semiconductor circuit will need between 12 and 25 masking layers.

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Scanning Electron Microscope (SEM)

A microscope that uses an electron beam to image very small features. SEMs have much higher resolutions than optical microscopes. SEMs are used in semiconductor manufacturing for measuring the widths of circuit geometries.

SCBA

Self-Contained Breathing Apparatus. Typically 1-2-air tanks worn on the back and connected to a full-face mask respirator.

SDL

System Detection Limit. Describes the sensitivity of the instruments used for detecting gases during permeation testing. This limit is determined prior to each permeation test by exposing the detection device to a minimum known quantity of the challenge chemical which will produce a measurable signal. SDL is expressed in parts per million.

Seam

Where two sections of a garment are joined. There are several types available; examples include felled, serged, bound, taped.

Serged seam

A seam where three threads are interlocked around the raw edges of two plies of material.

Silicon

Pure silicon is used to make almost all the semiconductor chips currently sold on the market. Silicon is not the only semiconductor that can be used to make integrated circuits, but it does have many properties that make it much better for this purpose than the other known semiconductors. When silicon is combined with oxygen it becomes silicon dioxide.

Silicon Dioxide

Sometimes just called oxide in the semiconductor industry. Sand on the beach and the glass from which we make bottles is silicon dioxide. Silicon dioxide is an insulator, and is used in semiconductor circuits to isolate different conducting regions. Silicon dioxide can be grown from silicon by exposing it to oxygen at high temperatures, or it can be deposited using chemical vapor deposition.

SMIF (Standardized Mechanical Interface)

A wafer manufacturing concept in which wafers are kept in sealed pods when they are not being processed in machines. One of the original drivers for SMIF was the thought that this would reduce particle contamination and possible render large-scale cleanrooms obsolete.

Spin Coater

Also called a resist track or a tract. A machine for applying photoresist uniformly to a wafer by spinning the wafer during or after pouring on the photoresist. Spin coaters are also used for developing resist. In addition they can be used for coating wafers with other liquid films.

Spin Tool

Sometimes called a spin-rinse-dryer or SRD. This is a machine for etching or cleaning wafers in wet chemicals. It is constructed like a front loading laundry machine. A cassette holding its wafers is turned round and round as chemicals are dispensed over the wafers. Wafers are rinsed in de-ionized water, and dried by spinning at high speeds.

Splash Protection

Protection from physical contact with a liquid.

Spray tool

This is a machine for etching or cleaning wafers in wet chemicals. It works like a dishwasher in that chemicals are sprayed at the wafers. The cassettes holding the wafers are rotated while this is happening.

Sputtering

A form of physical vapor deposition (PVD) often used for deposition of metal films. Sputtering involves knocking metal atoms off a disc of pure metal with charged, energetic, chemically inactive atoms called ions (from a plasma). The metal atoms will re-deposit onto the wafer to build up the desired metal film.

Static electricity

Electrical charges generated by friction.

Steady state

Refers to flow rate in permeation testing. The point at which the challenge chemical has begun to permeate the fabric, and the rate of permeation flow is neither increasing, nor decreasing.

Stepper

A photolithography machine used to expose a pattern on a wafer by shining light through a reticle (a glass plate containing a pattern etched in chrome). Since it cannot accurately expose the entire wafer at once, a stepper exposes an area of a smaller size and keeps repeating this until the whole wafer is covered. This process is called step and repeat. An eight-inch wafer might need about 80 fields for full exposure.

Stockers

Automated storage units for wafers when they are not being processed.

Storm Flap

Splash guards constructed from the primary suit material which help keep liquids off the zipper, valves, boots or other components.

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Taped seam

A very strong seam produced when a sewn seam is covered with a strip of compatible material. The strip is attached by heat sealing as with film laminated materials.

TES

Totally Encapsulating Suit – A full coverage suit where the head, arms, torso, and legs are fully protected. Not necessarily gas tight.

Tester

A piece of electronic equipment designed to test chips to check if they work, and if so, how well (usually how fast) they work. Testers are usually specialized as either memory chip testers, digital logic chip testers, or analog chip testers, though some of the more sophisticated testers can deal with more than one of these groups.

Thermal Heat

Direct heat transfer from a source, non-radiant, as in a burning liquid splashed onto a chemical suit.

Thermoplastics

Heat welded or heat laminated fabrics such as PVC or CPE.

Third Party Testing

Testing not performed by any parties who might financially profit by test outcome. Ensures objective, fair test results.

Tongue Tear

A physical test that determines the force (non-shear) required tearing a fabric.

Toxicity

Level of poisonous effects from a chemical.

Track

Sometimes called resist track. A common name for a spin coater.

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Vapor pressure

The pressure created by a gas at any given temperature in equilibrium with its liquid state. The pressure build up (particularly in warm weather) in a car fuel tank is an example of vapor pressure.

Viton

Trademark name for a series of flouroelastomers based on the copolymer of vinylidene fluoride and hexaflouropropylene. A common elastomeric with fair to good chemical holdout.

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Wafer

Semiconductor processing is done on round disks of silicon called wafers. A current generation wafer is 8 inches in diameter, the thickness of a credit card, weighs about a third of a pound, and is polished to a mirror finish on one side. It is silvery gray in color.

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.

Wire bonding

The linking of a chip with the outside world. This involves connecting each of the contact pads (fabricated on the chip) with the metal leads of the package by joining one end of a gold (or aluminum) wire to the pad and the other end to the corresponding lead. The bonds are formed by applying heat, pressure and/or sonic vibration.

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