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Back end
In semiconductor manufacturing, the package assembly and test stages of production. Includes burn-in and environmental test functions. Compare front end.
Back end manufacturing
The portion of semiconductor manufacturing that happens after the wafer has left the clean room. 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. Much of the assembly capacity is based in the Pacific Rim countries.
Back End-Of-Line (BEOL)
process steps from contact through completion of the wafer prior to electrical test. Also called back end.
Back oxide
a layer of silicon dioxide formed on the back of a wafer during oxidation.
Back plate
in a flat panel display, for a panel that consists of two plates of glass (or substrates) bonded together, the plate farthest from the viewer of the display.
Back surface
of a semiconductor wafer, the exposed surface opposite to that on which active semiconductor devices have been or will be fabricated. Also called backside.
Backgrind
an operation using an abrasive on the back side of a substrate to achieve the necessary thinness for scribing, cutting, and packaging of die.
Background
in the bar code marking of silicon wafers, the uniform, lighter or more reflective region that provides contrast for the darker bars of a bar code symbol, including the "quiet zones."
Background counts
in particle counting, signal of particle counts that is observed during analysis of a particle-free standard test specimen. Background particle counts include electronic noise, particles contributed by the test apparatus, and signals induced by surface roughness.
Backside
see back surface.
Bake
in wafer manufacturing, a process step in which a wafer is heated in order to harden resist, remove moisture, or cure a film deposited on the wafer.
Balancing
in equipment exhaust systems, adjustments made after the ventilated equipment and the ventilation system are installed to ensure that air flow to each piece of ventilated equipment is within design specifications.
Ball Grid Array (BGA)
an integrated circuit surface mount package with an area array of solder balls that are attached to the bottom side of a substrate with routing layers. The die are attached to the substrate using die and wire bonding or flip-chip interconnection. Also called land grid array, pad grid array, or pad-array carrier.
Ball valve
a shutoff valve of the packed type that incorporates a round, internal dynamic member, or "ball," and containing one or more through holes that connect the ports of the valve to each other. Also see packed valve.
Bandwidth
the difference between the highest and lowest values in a range of two pattern characteristics, such as efficiency, frequency, or impedance. The bandwidth of significant frequencies (frequencies that conform to standards or that are required for reliable frequencies) within a spectrum is expressed in hertz.
Banking pins
in flat panel display, round elements in a positioning fixture that define a coordinate system origin, and against which a substrate is placed for processing or inspection.
Bar
see die, crossbar, and bar end.
Bar code
in the bar code marking of silicon wafers, an array of parallel rectangular bars and spaces that together represent data elements of characters in a particular symbology. The bars and spaces are arranged in a predetermined pattern following unambiguous rules defined by the symbology, that is, BC-412.
Bar code character
in the bar code marking of silicon wafers, a single group of bars and spaces that represent an individual number, letter, punctuation mark, or other symbol.
Bar end
1: in the bar code marking of silicon wafers, the darker or less reflective element of a bar code symbol. 2: of a wafer carrier, see crossbar.
Bar radius
in plastic and metal wafer carriers, the radius nearest the bar end of the carrier on the crossbar.
Bar web
in plastic and metal wafer carriers, the mass of material for structural support that may or may not be present on the crossbar.
Bar width
in plastic and metal wafer carriers, the distance or thickness of the bar when measured perpendicular to the top face. Also see crossbar.
Bare die
individual, unpackaged silicon integrated circuits.
Barrier
a physical layer designed to prevent intermixing of the layers above and below the barrier layer; for example, titanium-tungsten and titanium-nitride layers.
Barrier layer
see depletion layer.
Base
1: in semiconductor manufacturing chemicals, a substance that dissociates in water to liberate hydroxyl ions, accepts a proton, has an unshared pair of electrons, or reacts with acid to form a salt. A base has a pH greater than 7 and turns litmus paper blue. 2: in facilities and safety, a corrosive material with the chemical reaction characteristic of an electron donor. 3: in quartz and high temperature carriers, the material at the bottom of a wafer carrier on which the wafer carrier rests when placed on a flat surface. 4: of a cerdip or cerpack package, the bottom ceramic portion. A leadframe, a window frame, and the cap are attached to the base-generally with devitrifying solder glass-during package/device manufacture.
BASE council
see TQM-BASE Council.
Base end to first slot
in quartz and high temperature wafer carriers, the distance from either end of the base of a wafer carrier to the first slot.
Base length
in plastic and metal wafer carriers, the length of the base of a wafer carrier from end to end.
Base side to wafer center line
in plastic and metal wafer carriers, the horizontal distance from the vertical wafer center line to either side of the base.
Base step height
in quartz and high-temperature wafer carriers, the distance from the bottom plane to the widest point of the base.
Base width
in quartz and high-temperature wafer carriers, the outside dimension of the base from side to side.
Baseline
a specification or product that has been formally reviewed and agreed on, which thereafter serves as a basis for further development and can be changed only through formal change control procedures. (Copyright 1993 IEEE. All rights reserved.)
Basic cell
an arrangement of features or groups, as defined by SEMI P19-92, based on a specific nominal feature dimension.
Batch
1: one or more sets of data or programs accumulated for processing in one noninteractive job. 2: a group of wafers intended for a process sequence, as opposed to single-wafer processing.
Bay
of a cleanroom, a confined area that contains equipment used for one or more steps in a process.
Bead
an individual spherical particle of an ion-exchange resin material.
Behavior
in object-oriented technology, how an object acts and reacts.
Behavioral
a level of logic design that involves describing a system at a level of abstraction that does not involve detailed circuit elements, but instead expresses the circuit functionality linguistically or as equations.
Behavioral simulation
The ability to simulate the behavior of a function described by a high-level descriptive language such as C, Pascal, Verilog HDL and VHDL.
Bell jar
a glass, quartz, or stainless steel chamber used to isolate substrates in a subatmospheric environment for deposition or etch.
Bellows valve
a packless valve that incorporates a statically sealed bellows to isolate the controlled medium from the atmosphere.
Benchmarks
standard circuits or tests that can be used to compare the performance of software programs or tools. Each program or tool is applied to the benchmark circuit and the results compared.
Bend radius
of a fluorocarbon tube, the distance from the center of an imaginary circle on which the arc of the bent tube falls to a point on that arc.
BEOL
see back end-of-line.
Best focus
in the testing of photolithographic instruments, the position of a processed image surface in which the best compromise of focus across the whole of the processed image is obtained, as defined by the application requirements for the processed image.
Beta distribution
see Pearson distribution.
Beta test
performance testing done on a pilot production version of a process tool installed at customer sites. The testing is performed by customers and monitored by the manufacturer's applications engineering group. No design changes are made during the testing period.
Bevel angle
the smaller of the angles between the wafer surface and the section plane.
BGA
see ball grid array.
BHT
see Brinell hardness test.
BiCMOS
Bipolar Complementary Metal Oxide Semiconductor. An IC technology combining the linearity and speed advantages of bipolar and the low-power advantages of CMOS on a single IC. BiCMOS can operate at either ECL (emitter-coupled-logic) or TTL (transistor-transistor-logic) levels, and is ideal for mixed-signal devices. It has been predicted that BiCMOS will eclipse CMOS in the '90s, just as CMOS edged out MOS and bipolar circuits in the '80s.
biCMOS design
the combination of bipolar and complementary metal oxide semiconductor design and processing principles on a single wafer or substrate.
Bidirectional
in the bar code marking of silicon wafers, refers to a bar code that can be read successfully in either scanning direction, right to left or left to right.
Bimetal mask
see mask, bimetal.
BiMOS
Bipolar Metal Oxide Semiconductor. A general term to refer to bipolar and MOS on one chip. Sometimes used interchangeably with "BiCMOS." See also Power BiMOS.
Bin
of particle measurement instruments, a subset of the total range of particles counted, based on size. Many particle counting instruments measure the size of a particle while counting and then sort the total number of counts into bins. Some instruments have the size ranges of the bins set at the factory, while some designs allow the user to set the ranges of the bins. Also called channel.
Binary Intensity Mask (BIM)
a mask consisting of patterned areas that transmit or do not transmit, for example, the common chrome-on-quartz mask.
Binary number system
A number system employed in computers and digital systems, in which successive digits are coefficients of powers of the base 2, rather than the base 10. For example, the decimal number 13 is represented by the binary number 1101 (1 x 23 + 1 x 22 + 0 x 21 + 1 x 20). Since the only values in the binary system are "0" and "1," quantities, or BITS (binary digits) are represented electronically with either of two conditions, typically a high voltage representing a "1" and a low voltage representing a "0". See bit.
Binary value
in the dot matrix code marking of silicon wafers, a dot in the wafer surface indicates the binary value 1. The absence of a dot, or a smooth surface surrounding a cell center point, indicates the binary value 0.
Binding energy
the value obtained by subtracting the instrumentally measured kinetic energy of an electron from the energy of the incident photon, corrected for an instrument work function.
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 chips have been packaged, they are tested one more time to see if they work and how well they perform.
Biodegradable
pertains to an organic material capable of decomposition as a result of attack by microorganisms.
Biofilm
a collection of microorganisms, extracellular polymeric products, and organic matter located at the interface in solid-liquid, gas-liquid, or liquid-liquid biphasic systems.
Bipolar
a semiconductor device fabrication technology that produces transistors which use both holes and electrons as charge carriers.
Bipolar transistor
An active semiconductor device formed by two P-N junctions whose function is amplification of an electric current. Bipolar transistors are of two types: NPN and PNP, depending on the manner in which the two P-N junctions are combined. Bipolar transistors have three sections: emitter, base, and collector. Operation of a bipolar transistor depends on the migration of both electrons and holes, in contrast to field-effect transistors, where only one polarity carrier predominates.
Bipolar transmission
see polar transmission.
BIR
Building In Reliability.
Bird's beak
a structural feature produced as a result of the lifting of the edges of the nitride layer during subsequent oxidation.
Birefringence
a double-refraction phenomenon in which an unpolarized beam of light is divided into two beams with different directions and relative velocities.
BIST
see built-in self test.
Bit
Binary digit. A digit (1 or 0) in the representation of a number in binary notation. The smallest unit of information recognized by a digital computer. Used to represent two states in the binary number system. Eight bits make a byte. See binary number system.
Blister ceramic
an enclosed, localized separation within or between the layers of a ceramic package that does not expose an underlying layer of ceramic or metallization. Also called bubble ceramic.
Blister metal
in packaging, an enclosed, localized separation of a metallization layer from its base material (such as ceramic or another metal layer) that does not expose the underlying layer. Also called bubble metal, blister metallization, and bubble metallization. Also see package.
Block
in message transfer, a physical division of a message (a complete unit of communication). NOTE-In SECS-I, each block has a block header (a 10-byte data element used by the message and transaction protocols) and up to 244 bytes of data. For compatibility with SECS-I, SECS-II also recognizes the same block length for data; however, in SECS-II there is only a message header, not a header for each block.
Block length
in message transfer, the number of bytes sent in the block transfer protocol.
Block number
a 15-bit field in the header for the numbering of blocks in a message. Also see multiblock message.
Block structure
see cell structure.
Block transfer protocol
in message transfer, the SECS-I procedure used by a serial line to establish the direction of communication and to provide the environment for passing message blocks. NOTE-A block consists of a 10-byte header plus up to 244 bytes of data. Also see message protocol.
Blocking layer
see depletion layer.
Block-level
describes a high-level architectural schematic of a system or function that hides detail and displays a collection of circuit elements as a single block.
Boat
see quartz carrier.
Boat map
a drawing that shows the relative location of product, test, and dummy wafers in a diffusion cycle.
Boiling Point (bp)
the temperature of a liquid at which the vapor pressure equals the prevailing atmospheric pressure. The normal boiling point is specified at one atmosphere.
BOM
Bill of Materials. List of specifications that uniquely defines manufacturing sequence, materials and procedures utilized in the manufacture of a specific product.
Bond finger
1: in ceramic packages, an area of refractory metal that has been plated, usually with gold, and is intended for wire bonding. Also see lead flat surface. 2: the area of leadframes designated for the attachment of bonding wires between the bond pads on the die and the leadframe.
Bondability
surface conditions (cleanliness) of a bonding area that provide a capability for successfully bonding an interconnection material.
Bonded process
a manufacturing-oriented technique to build silicon on insulator substrates. The process involves bonding two oxidized wafers together then thinning the top or active layer to the desired thickness.
Bonded wafer
A composite dielectrically isolated substrate formed by fusing together (at high temperature) the oxidized surfaces of two individual silicon substrates. Bonded wafers are being developed to extend the DI (dielectric isolation) technology to wafers as large as six inches in diameter. ICs formed in such wafers provide higher breakdown voltage and a higher level of radiation resistance than devices fabricated in conventional DI substrates.
Bonding
The process of connecting wires from the package leads to the chip (or die) bonding pads. Part of the assembly process. Alternately, the process of securing a semiconductor die to a lead frame or package. See bond pad.
Bonding area
in packaging, the area of a leadframe designated for the attachment of small diameter bonding wires from the bonding pads on the die to the leadframe. These areas are often coined if the leadframes are stamped to provide a flat surface for bonding. The designated area does not necessarily correspond to the physical dimensions of the bond finger. Also see lead flat surface and package.
Bonding pads
relatively large metal areas on a die used for electrical contact with a package or probe pins.
Booties
conductive shoe covers worn to reduce contamination in a cleanroom.
Border column
in the dot matrix code marking of silicon wafers, the outermost column of a dot matrix.
Border row
in the dot matrix code marking of silicon wafers, the outermost row of a dot matrix.
Boron (B)
a nonmetal that is also a p-type dopant for silicon. The most common source of boron is the gas diborane (B2H6).
Boron implant
the operation whereby boron atoms are accelerated and injected into the surface of a wafer or substrate. The species are physically implanted into the bulk of the silicon to create a locally conductive p-type area.
Boron trichloride (BCl3)
a colorless gas at room temperature and atmospheric pressure. Boron trichloride fumes in the presence of moist air and has a choking odor. This gas is used as a gas etchant of metals such as aluminum. It also is used in boron doping.
Boron trifluoride (BF3)
a colorless gas that fumes in moist air and has a pungent odor. This gas is nonflammable and does not support combustion. It is toxic when inhaled and is corrosive to the skin. Boron trifluoride is used in ion implantation and doping.
Bottom formed width
in packaging, the widest spread of the leads, measured to the outside of the lead or foot, after lead forming. Also see leadframe and package.
Bottom plane
in a wafer carrier, a horizontal plane tangent to the base.
Bottom protrusions
see top or bottom protrusions.
Boundary scan
a scan path that allows the input/output pads of an integrated circuit to be both controlled and observed.
Bow
of a semiconductor wafer, the deviation of the center point of the median surface of a free, unclamped wafer from a median-surface reference plane established by three points equally spaced on a circle with diameter a specified amount less than the nominal diameter of the wafer. Contrast flatness. Also see warp.
Box
an environmentally controlled enclosure for a cassette containing wafers or disks. A box includes a box door and box latches. Also called container.
Box door
a removable bottom for the box that contains a means (such as registration holes) for properly positioning the wafer cassette.
Box latches
for wafers less than or equal to 150 mm, mechanical latches that hold the box door in position until activated by the latch pins. Upon activation, a portion of each box latch engages a latch cavity and smaller, thereby locking the box to the port plate.
BPSG
BoroPhosphoSilicate Glass. BPSG is an oxide primarily used as a field dielectric. It is deposited in a PECVD reactor using a mixture of SiH4, B2H6, and PH3 with N2O in a temperature and pressure controlled environment. BPSG is used principally because of its' lower melting point (viscous flow temperature) compared to other oxides. BPSG can be deposited over delineated polysilicon and can 'flow' at temperatures low enough to not significantly alter the dopant profiles in the underlying device silicon. This smoothing improves metal-level step coverage. BPSG is not a good passivation material because it is hydroscopic in nature. See PECVD
Braze
1: to join two metals together through the use of a third metal or alloy at or above 427 degrees C (800 degrees F). The braze material alloys with each of the two metals that do not alloy with each other. Leads and seal rings may be brazed to designated nickel plated, refractory metallization areas of the package. Contrast solder. 2 n : a material used for brazing, usually a silver/copper (72/28) alloy with a melting point of 779 degrees C.
Bridge
1: a defect in which two adjacent areas connect because of misprocessing such as poor lithography, particle contamination, underdevelop, or etch problems. Also called short. 2: software that allows access to, and combination of, data from incompatible databases.
Bridged interface
a general term for the interconnection between legacy systems.
Bridging fault
a fault modeled as a short-circuit between two nets on a die.
Brightfield illumination
(transmission electron microscopy) : the illumination of an object so that it appears on a bright background.
Brinell Hardness Test (BHT)
an indentation hardness test using calibrated machines to force a hard ball, under specified conditions, into the surface of the material under test and to measure the diameter of the resulting impression after removal of the load.
Bronchitis
an acute or chronic inflammation of the mucous membrane of the tracheobronchial tree.
Browse
to view the components of a structure through a user interface that allows easy navigation through the links connecting objects in the structure.
Browser
a basic tool for the manipulation of a repository; , displaying its objects, links and attributes. The browser also acts as a repository editor, allowing the creation and deletion of objects, modification of links and attributes, etc.
BTAB
see bumped tape automated bonding.
Bubble
a spherical defect formed by air or other gas included in a substrate or film.
Bubble ceramic
see blister ceramic.
Bubble fluid
a liquid, containing soap or other bubble-generating medium, designed to detect leaks from inside a piping system to atmosphere.
Bubble metal/metallization
see blister metal.
Buffer
1 a program routine or storage device that compensates for unequal data flow rates or event timing differences during the transfer of data between devices. 2: a substance added to a solution to attain higher consistency of solution strength over time.
Buffered hydrofluoric acid
an extremely hazardous corrosive used to etch silicon dioxide from a wafer. This acid has a 20- to 30-minute reaction delay after contact with skin or eyes.
Built-In Self Test (BIST)
any of the methods of testing an integrated circuit (IC) that uses special circuits designed into the IC. This circuitry then performs test functions on the IC and signals whether the parts of the IC covered by the BIST circuits are working properly.
Bulk gases
common gases, such as nitrogen, hydrogen, oxygen, and argon that are used in such large quantities in wafer fabrication that they are pumped or piped into the facility.
Bulk processes
semiconductor processes affecting the bulk silicon, for example, silicon materials, implant, cleans and thermal processes.
Bumped Tape Automated Bonding (BTAB)
the preparation of a raised bump site, usually gold or tin, at each bond site on tape bonding material. Also see tape automated bonding.
Bunny suit
a total-body garment worn by personnel in a cleanroom to reduce release of particles and contaminants into the air.
Buried contact
a conductive region between two less conductive regions.
Buried layer
1: a conductive layer between two less conductive films; for example, a localized n+ region in a p-type wafer that reduces the npn collector series resistance for integrated circuit transistors fabricated in an n-type epitaxial layer deposited on the p-type wafer. 2: in epitaxial silicon wafers, a diffused region in a substrate that is, or is intended to be, covered with an epitaxial layer. Also called subdiffused layerand diffusion under film.
Burn-in
the process of exercising an integrated circuit at elevated voltage and temperature. This process accelerates failure normally seen as "infant mortality" in a chip. The resultant tested product is of high quality.
Burr
1: an adherent fragment of parent material at a component edge. In leadframes, due to the stamping operation, the metal burr may be in a horizontal or vertical direction relative to the surface. In ceramic packages, this type of characteristic is called a fin. 2: in cerpack packages, a fragment of excess material or foreign particle adhering to the surface.
Bus
Four or more parallel conductors in an information processing system along which information is transmitted from one part to another. The microprocessor, peripherals, memory and other components are interconnected by a common bus.
Bus driver
An integrated circuit added to the bus to facilitate sufficient drive to the CPU when several peripheral devices are tied to the bus. Drivers are necessary because of capacitive loading, which slows down the data rate and prevents proper time sequencing of system operation. See buffer.
Byte
From the expression "by eights." A group of eight contiguous bits (binary digits) handled as a unit in computer processing. A byte can store one alphanumeric character. A kilobyte (KB) is 1024 bytes or 8192 bits. A megabyte (MB) is 1024 kilobytes or 1,048,576 bytes or 8,388,608 bits.
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