Technical Glossary | Lam Research

Technical Glossary

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  • µm

    see micron
  • 3D IC

    an integrated circuit (IC) formed by stacking wafers and/or dies vertically (three-dimensional) and connecting them electrically using through-silicon vias
  • 3D NAND

    a device architecture in which memory cells are arranged vertically (three-dimensional), rather than horizontally (planar) to increase memory bit density
  • 3D TRANSISTOR

    a transistor architecture formed vertically (three-dimensional, for example, a FinFET), rather than horizontally (planar)

A

  • Å

    see angstrom 
  • AHM

  • ALD

  • ALE

  • ANGSTROM (Å)

    a unit of length equal to 1 x 10−10 meters
  • ANISOTROPIC

    in semiconductor manufacturing, a term used to describe a process that is directional (versus isotropic, or uniformly in all directions)
  • ANNEAL

    a process used to change the properties of materials through controlled heating
  • ANTI-REFLECTIVE LAYER (ARL)

    a thin layer of light-absorbing material deposited on top of reflective materials on the wafer to improve photolithography results
  • AR

  • ARL

  • ASHABLE HARDMASK (AHM)

    a carbon-based patterning film often used for its ability to provide better selectivity to and protection of underlying layers than conventional photoresist; easily removed by a dry process, such as ashing
  • ASHING

    a type of strip process that removes organic materials, typically photoresist, by using heat and plasma
  • ASPECT RATIO (AR)

    the comparison of the height to the width of a geometric shape (for example, 20:1)
  • ATOMIC LAYER DEPOSITION (ALD)

    a deposition technique that lays down a thin film, typically a few atomic layers at a time; uses cycles of sequential, self-limiting reactions
  • ATOMIC LAYER ETCHING (ALE)

    an etch technique that removes materials, typically a few atomic layers at a time; uses cycles of sequential, self-limiting reactions

B

  • BACK END

    the set of process steps including packaging (external connection) and device testing that complete semiconductor manufacturing; follows front end processes
  • BACK-END-OF-LINE (BEOL)

    the set of steps that form the interconnect structures (wiring); follows front-end-of-line (transistors) and middle-of-line (contacts) processes
  • BARRIER

    a thin layer deposited between two materials to prevent their interaction
  • BEOL

  • BEVEL

    the rounded or slanted area of the very edge of a wafer
  • BEVEL CLEAN

    a process that removes unwanted material from the wafer's edge that can otherwise migrate to the active die area and negatively impact device performance or yield; may be a dry process (using plasma) or wet process (using liquid chemicals)
  • BIT LINE

    the path used to read and write information to memory cells; connects the sources/drains of the cells in a column that makes up a two-dimensional array

C

  • CAPACITIVELY COUPLED PLASMA (CCP)

    a type of plasma source in which the plasma is formed between two electrodes, typically closely spaced, which are connected to an RF power supply (one may also be connected to ground)
  • CAPACITOR

    a component used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator; used in both logic and memory devices
  • CCP

  • CD

  • CHANNEL

    the conductive path electrons (or holes) follow through a semiconductor; current flow through the channel is controlled by voltage applied across the gate and source terminals
  • CHEMICAL VAPOR DEPOSITION (CVD)

    a process that uses controlled reactions of volatile chemicals to deposit a dielectric or conductive film
  • CHIP

    short for “microchip”; a set of electronic circuits on a small section of a semiconductor wafer; also called a die
  • CLEANING

  • CLEANROOM

    an enclosed area strictly controlled for airborne contamination, humidity, and temperature to be suitable for manufacturing semiconductor devices
  • CMOS

  • COMPLEMENTARY METAL OXIDE SEMICONDUCTOR (CMOS)

    a common type of semiconductor technology that uses complementary pairs of p-type and n-type metal oxide semiconductor field effect transistors (MOSFETs) for logic functions
  • CONDUCTOR

    a material in which electricity flows easily (for example, a metal) that is used to electrically connect components in a semiconductor device
  • CONFORMAL

    a term used to describe uniform coverage of a layer of material over pre-existing topography; thickness of the layer remains the same everywhere on the surface of the feature
  • CONTACT

    the conductive connection between the transistor and the first interconnect layer
  • COPPER INTERCONNECT

    the connections (wiring) of an integrated circuit using copper as the conductive material; offers higher electrical conductivity (faster) than aluminum interconnect
  • COPPER OVERBURDEN

    excess copper deposited on top of the wafer after filling vias and trenches; later removed using chemical-mechanical planarization (CMP)
  • CRITICAL DIMENSION (CD)

    a dimension that must be precisely fabricated to ensure proper device performance and/or yield
  • CVD

D

  • DAMASCENE

    a technique of forming conductive connections (wiring) between circuits by inlaying conductive materials, such as copper, into insulating layers
  • DEEP SILICON ETCHING

    an anisotropic (directional) plasma etch process that creates high aspect ratio (tall and narrow) features in silicon; applications include MEMS devices and TSV structures
  • DEFECT

    any contamination (such as particles or residues) or structural flaw (such as voids); can negatively impact device performance and/or yield
  • DEFECTIVITY

    a measure of the level or degree of defects, including quantity, size, and type; often a comparison against a desired or acceptable level
  • DEPOSITION

    a process that lays down the insulating or conducting materials that make up a semiconductor device
  • DESCUM

    a process that removes a very light organic residue, for example, at the bottom of a trench; typically a plasma process
  • DEVICE GENERATION

  • DIE

    a term used to describe a single semiconductor chip on a wafer
  • DIELECTRIC

    a non-conductive material used to insulate conductive components in a device
  • DIRECTED SELF-ASSEMBLY (DSA)

    a patterning technology that uses block co-polymers to define patterns
  • DOUBLE PATTERNING

    a multiple patterning technique that increases feature density by a factor of two compared to using a single lithography step; involves either decomposing the mask into two easier-to-print lithography steps or using self-aligned double patterning (SADP)
  • DPT

    double patterning technology; see double patterning 
  • DRAM

  • DSA

  • DYNAMIC RANDOM ACCESS MEMORY (DRAM)

    a type of volatile memory (needs power to retain data) that can be electrically refreshed; with dynamic RAM, each bit of data is stored in a separate capacitor, which needs to be refreshed repetitively

E

  • ECD

  • ECP

    electrochemical plating; see electrochemical deposition 
  • EDGE EXCLUSION (EE)

    the outermost distance from the wafer's edge, usually indicated in millimeters, where it is generally more difficult to achieve good process results; the lower the edge exclusion, the larger the wafer area where good process results are achieved
  • EE

  • ELD

  • ELECTROCHEMICAL DEPOSITION (ECD)

    a plating technique that deposits a metal layer by passing an electrical current through a chemical solution using the wafer as an electrode; also referred to as electrochemical plating (ECP) or electroplating
  • ELECTROLESS DEPOSITION (ELD)

    a plating technique that deposits a metal layer using a chemical process and relies on the presence of a reducing agent; unlike electrochemical deposition, electroless deposition does not use external electrical power
  • ELECTROMIGRATION

    the movement of atoms or ions in a metal line (interconnect) during high current flow through momentum transfer from electrons to metal atoms; can create voids in the line and eventually prevent current flow or cause device failure
  • ELECTROPLATING

  • ELECTROSTATIC CHUCK (ESC)

    a piece of hardware that holds the wafer in place by using a static voltage field, in contrast to vacuum-based or physical clamping
  • ESC

  • ETCH

    a process that selectively removes material to create desired features and patterns of a semiconductor device; includes dry (using plasma) and wet (using liquid chemistries) processes

F

  • FAB

    a facility that manufactures semiconductor products; short for “fabrication”
  • FEOL

  • FET

  • FIELD EFFECT TRANSISTOR (FET)

    a type of transistor that uses an electric field to control the electrical conductivity of a channel in a semiconductor material
  • FINFET

    a 3D transistor architecture with tall, fin-like structures that enables smaller overall device dimensions and lower power relative to those with planar (side-by-side) transistors of similar feature sizes
  • FLASH MEMORY

    a non-volatile type of memory (does not need power to retain data) that can be electrically erased and rewritten; a common form of flash memory is NAND
  • FLIP CHIP

    a packaging method that creates electrical connections between semiconductor devices by “flipping” the chip face-down to bond to the external circuitry
  • FOUNDRY

    a wafer fabrication facility that manufactures another company's semiconductor products as a service
  • FOUP

  • FRONT END

    the set of wafer processing steps that include forming the transistors (front-end-of-line, FEOL), contacts (middle-of-line, MOL), and wiring (back-end-of-line, BEOL); followed by back end processes
  • FRONT-END-OF-LINE (FEOL)

    the set of process steps to form transistors and other circuit elements (such as resistors and capacitors) that are later connected electrically with middle-of-line (contacts) and back-end-of-line (wiring) processes
  • FRONT-OPENING UNIFIED POD (FOUP)

    a specialized wafer carrier used to transport wafers from one processing tool to the next; used to minimize exposure to contamination

G

  • GAA

  • GAPFILL

    a type of deposition process that fills narrow spaces with insulating or conducting material
  • GATE

    one of three terminals of a field effect transistor; current flow between source and drain terminals is controlled by applying or removing voltage to the gate
  • GATE STACK

    the set of insulating and conducting layers that make up the gate of a field effect transistor
  • GATE-ALL-AROUND (GAA) FET

    a type of three-dimensional, multi-gate field effect transistor (FET) designed to have a gate wrapping around all sides of the channel; improves current flow control while enabling continued transistor scaling; also referred to as nanowire FET

H

  • HAR

  • HARDMASK

    a film that is more resistant to etching than conventional photoresist, thereby better protecting underling layers from alteration; typically used when high-selectivity etching is required
  • HDP-CVD

  • HIGH ASPECT RATIO (HAR)

    refers to very tall and narrow device features, for example, DRAM capacitor cells; the higher the aspect ratio of a feature, the more challenging it is to create; see also aspect ratio 
  • HIGH-DENSITY PLASMA CHEMICAL VAPOR DEPOSITION (HDP-CVD)

    a CVD process that employs an inductively coupled plasma (ICP) source to deposit material; the ICP source generates a higher plasma density than typical occurs in PECVD
  • HIGH-K DIELECTRIC

    an insulating material with a high dielectric constant (k) value (for example, hafnium oxide) that is used in a transistor gate stack to lower transistor leakage

I

  • IC

  • ICP

  • ILD

  • IMD

  • INDUCTIVELY COUPLED PLASMA (ICP)

    a type of plasma source in which plasma is formed when radio frequency (RF) energy is coupled into a gas by an inductive coil through transformer action
  • INFLECTION

    a revolutionary change in process technology; these changes, in turn, drive development of new semiconductor manufacturing capabilities; examples include the change from aluminum to copper interconnects and the introduction of multiple patterning techniques
  • INTEGRATED CIRCUIT (IC)

    a single, complete semiconductor product of electrically connected components (such as transistors and capacitors) fabricated on the same substrate
  • INTERCONNECT

    the intricate wiring that forms electrical connections between components in an integrated circuit
  • INTERLAYER DIELECTRIC (ILD)

    an insulating material that provides electrical isolation between conducting layers
  • INTERMETAL DIELECTRIC (IMD)

    an insulating material that provides electrical isolation between metal lines
  • ISOTROPIC

    in semiconductor manufacturing, a term used to describe a process that is the same in all directions (versus anisotropic, or directional)

J

K

  • K VALUE

    dielectric constant, the measure of a material’s ability to store an electric charge

L

  • LED

  • LELE

  • LIGHT-EMITTING DIODE (LED)

    a semiconductor device that emits infrared, visible, or ultraviolet light when an electric current flows through it
  • LITHO/ETCH/LITHO/ETCH (LELE)

    a double patterning process that involves splitting a given pattern into two less dense patterns to compensate for lithography resolution limitations; each pattern requires one lithography step and one etch step
  • LITHOGRAPHY

    a process that transfers patterns from a photomask to the wafer
  • LOGIC

    a chip consisting of circuit elements that together perform a function using various types of mathematical operations, for example, microprocessors; can be thought of as the “brains” of an electronic device
  • LOW-K DIELECTRIC

    an insulating material that has a dielectric constant (k value) lower than that of silicon dioxide (~3.9); commonly used in interconnect structures

M

  • MAGNETORESISTIVE RANDOM-ACCESS MEMORY (MRAM)

    a non-volatile memory technology that uses magnetic storage elements rather than conventional electric charges to store data
  • MASK

    a layer of material that protects certain areas of the wafer while other areas are being processed; generally later removed; also short for photomask, typically a transparent negative used to print a pattern during lithography
  • MEMORY CELL CAPACITOR

    the storage part of a DRAM cell; information is retained as a charge in the capacitor
  • MEMS

  • METAL GATE

    a type of transistor gate where the material used for the gate electrode is a metal, rather than traditional polysilicon
  • METAL HARDMASK (MHM)

    a metal layer that may be used in critical patterning applications to improve etch selectivity and profile control
  • METALLIZATION

    the process of depositing metal films, for example, the tungsten contacts and copper interconnects (wiring) in an integrated circuit
  • MHM

  • MICRO-ELECTROMECHANICAL SYSTEM (MEMS)

    a miniature device generally consisting of a central component for data processing (such as a microprocessor) and other components that interact with their surroundings (such as micro-sensors)
  • MICRON (µm)

    a unit of length equal to 1 x 10−6 meters; also known as micrometer
  • MICROPROCESSOR

    a type of logic chip; also called a central processing unit (CPU)
  • MIDDLE-OF-LINE (MOL)

    the set of wafer processing steps used to create the structures that provide the local electrical connections between transistors; mainly gate contact formation; occurs after front-end-of-line (transistors) and before back-end-of-line (wiring) processes
  • MILLIMETER (mm)

    a unit of length equal to 1 x 10-3 meters; commonly used in the semiconductor industry to describe the diameter of a silicon wafer, for example, a 300 mm wafer
  • mm

    see millimeter 
  • MOL

  • MOORE'S LAW

    an observation made by Gordon Moore in 1965 and later revised in 1975 that the number of transistors in an integrated circuit doubles roughly every two years, while the cost per IC decreases
  • MRAM

  • MSSD

  • MSSP

  • MULTI-STATION SEQUENTIAL DEPOSITION (MSSD)

    a tool architecture with multiple deposition stations designed to improve film uniformity; allows multiple wafers to be processed at the same time, thereby also improving productivity
  • MULTI-STATION SEQUENTIAL PROCESSING (MSSP)

    a tool architecture with multiple stations designed to improve process repeatability; also allows processing multiple wafers at the same time, thereby also improving productivity
  • MULTIPLE PATTERNING

    a manufacturing strategy used to create patterns that are more dense than would be possible with a single lithography step; involves decomposing a pattern into two or more separate, easier-to-print lithography steps or using a self-aligned patterning technique

N

  • NAND

    short for NAND flash memory; a type of memory cell that connects transistors in a way that resembles the NAND (not-and) logic operator; often used in memory cards, USB drives, and solid state drives
  • NANOMETER (nm)

    a unit of length equal to 1 x 10−9 meters; commonly used in the semiconductor industry to describe device dimensions as well as technology nodes, for example, the 10 nm node
  • nm

    see nanometer 
  • NON-UNIFORMITY

    a measure of the inconsistency or variation of a process result on the wafer, for example, changes in film thickness; low non-uniformity is desirable
  • NUCLEATION LAYER

    a thin layer of material generally used to aid subsequent metal film growth, for example, tungsten CVD for gapfill

O

  • OEM

  • ORIGINAL EQUIPMENT MANUFACTURER (OEM)

    a supplier that designs and manufactures equipment; in the semiconductor industry, distinguished from second-source suppliers who market components for equipment they do not design or manufacture
  • OXIDE

    an insulating material; usually refers to silicon dioxide (SiO2)

P

  • PACKAGING

    the process of enclosing a chip in a protective container (package) and providing power and signal connectivity
  • PARTICLE

    a miniature piece of unwanted material on the wafer; depending on its size and location, may be a defect that impacts device performance or yield
  • PATTERNING

    the processes involved in creating the features of an integrated circuit; includes design transfer using lithography and steps such as deposition and etch
  • PECVD

  • PHOTORESIST (PR)

    a photosensitive material used to transfer a pattern onto a wafer during photolithography; defines the areas that will subsequently be processed
  • PHOTORESIST STRIP

    a process that removes remaining photoresist from the wafer, typically following ion implant or etch processes; usually a dry process (using plasma) but may also be a wet process (using liquid chemicals)
  • PHYSICAL VAPOR DEPOSITION (PVD)

    a process that deposits a thin, conductive film by using sputtering
  • PITCH

    the distance from the center of one feature to the center of an adjacent feature, for example, from the center of one metal line to the center of an adjacent line
  • PLASMA

    a state of matter made up of free electrons and ions; created by sending a charge through a gas
  • PLASMA ETCH

    a process in which plasma is used to selectively remove material from the wafer through chemical and/or physical (ion bombardment) mechanisms
  • PLASMA-ENHANCED CHEMICAL VAPOR DEPOSITION (PECVD)

    a process that uses a plasma to lower deposition temperatures relative to conventional chemical vapor deposition (CVD)
  • PMD

  • PR

    see photoresist 
  • PRE-METAL DIELECTRIC (PMD)

    an insulating material that provides electrical isolation between the transistors and the first interconnect layer
  • PROCESS FLOW

    the order in which a set of semiconductor manufacturing processes is performed to fabricate devices on a wafer; there may be several hundred individual steps in a process flow

Q

  • QPT

    quadruple patterning technology; see quadruple patterning
  • QUADRUPLE PATTERNING

    a multiple patterning technique that increases feature density by a factor of four compared to using a single lithography step; involves either decomposing the mask into multiple easier-to-print lithography steps or using self-aligned quadruple patterning (SAQP)

R

  • RDL

  • REACTIVE ION ETCH (RIE)

    a plasma etch process involving chemically reactive species (ions) that are accelerated toward the wafer in a low-pressure environment
  • REDISTRIBUTION LAYER (RDL)

    an extra layer added to the chip during packaging to re-route electrical connection points 
  • RESIDUE

    unwanted material left on the wafer from previous processes; depending on the location and quantity, may be a defect that impacts device performance and/or yield
  • RIE

S

  • SAC

  • SADP

  • SAQP

  • SEED LAYER

    an ultra-thin film deposited to help initiate subsequent deposition; sometimes referred to as a nucleation layer
  • SELECTIVITY

    a measure of the different removal rates between two materials; the faster one material is removed relative to another, the higher the selectivity
  • SELF-ALIGNED CONTACT (SAC)

    a method of creating device contacts by using etch selectivities to follow the sidewall contour of the gate
  • SELF-ALIGNED DOUBLE PATTERNING (SADP)

    a multiple patterning technique that increases feature density by 2X by depositing a spacer film on the sidewalls of a lithographically defined feature, followed by removing that original feature; the remaining spacers are then used to define the final pattern
  • SELF-ALIGNED QUADRUPLE PATTERNING (SAQP)

    a multiple patterning technique that increases feature density by 4X by using repeated spacer films (similar to self-aligned double patterning) to define the desired pattern
  • SEMICONDUCTOR

    a material with electrical conductivity between that of a conductor and an insulator; silicon is a commonly used semiconductor
  • SEMICONDUCTOR MANUFACTURING

    the complete fabrication of semiconductor chips from front end (device and wiring) through back end (assembly, packaging, and test) processes
  • SEMICONDUCTOR MANUFACTURING EQUIPMENT

  • SHALLOW TRENCH ISOLATION (STI)

    a structure that separates neighboring transistors or memory cells; a shallow trench is etched then filled with an insulating material
  • SINGLE-WAFER CLEAN

    a process that removes particles and other materials one wafer at a time, in contrast to batch (multiple wafers); includes wet (using liquid chemistries) and dry (using plasma) processes
  • SIP

  • SPACER

    a deposited film commonly used to passivate sidewalls of the gate stack and to control the placement of dopants during ion implantation; also used to define the pattern in self-aligned multiple patterning schemes
  • SPIN CLEAN

    a wet clean process in which the wafer is rotated at high velocity while being treated with chemical solutions; removes films, particles, and other contaminants that could affect device performance or yield
  • STI

  • SUBSTRATE

    the starting material for the semiconductor manufacturing process, typically silicon; also referred to as a wafer
  • SYSTEM IN PACKAGE (SIP)

    a packaging technology that combines integrated circuits of different functionalities into a single module that performs as a unified system

T

  • TECHNOLOGY NODE

    commonly used to describe a device generation, for example, the 65 nm technology node is followed by the 45 nm technology node; historically referred to the smallest feature dimension
  • THERMAL BUDGET

    the maximum thermal energy (determined by processing temperature and time) allowed for wafer fabrication processes to meet desired device performance and yield requirements
  • THIN FILM DEPOSITION

    the process of forming sub-microscopic layers of conducting or insulating materials; includes dry processes (using plasma, such as PECVD) and wet (using liquid chemistries, such as ECD)
  • THROUGH-SILICON VIA (TSV)

    a high aspect ratio structure that creates vertical electrical connections through a die or a wafer; enables higher functionality and smaller form factor
  • TRANSISTOR

    a component that is used to amplify or switch electronic signals and electrical power; a primary component of an integrated circuit, which can contain up to several billion transistors
  • TRENCH

    a long, narrow feature formed by anisotropic (directional) etching; can be shallow or deep
  • TSV

U

  • UBM

  • ULTRA LOW-K DIELECTRIC

    an insulating material that has a dielectric constant (k value) generally less than 2.0-2.5; introducing porosity into the material is one way to obtain ultra low-k films
  • ULTRAVIOLET THERMAL PROCESSING (UVTP)

    a technique that modifies the characteristics of a film through exposure to ultraviolet (UV) light and heat; used, for example, to improve the integrity of low-k films
  • UNDERBUMP METALLIZATION (UBM)

    a metal deposition process that creates the electrical connection from the silicon die to a solder bump; used in packaging
  • UNIFORMITY

    a measure of the consistency of process results (such as etch CD); may be measured within a die, across a wafer, from one wafer to another wafer, etc.; high uniformity is desirable
  • UVTP

V

  • VARIABILITY

    a measure of the difference in process results (such as film thickness); may be measured within a die, across a wafer, from one wafer to another wafer, etc.; low variability is desirable
  • VIA

    an electrical pathway that connects two conductive layers
  • VOID

    a gap or hole defect where material is missing in a structure (such as a hole in a via); may be a defect that impacts device performance or yield

W

  • WAFER

    a round disk made of semiconducting material, often less than a millimeter thick; multiple chips are fabricated on each wafer; wafer sizes are defined by their diameter, for example, a 300 mm wafer
  • WAFER CLEANING

    the process of removing particles, contaminants, and/or other unwanted materials from the wafer during manufacturing; includes wet (using liquid chemistries) and dry (using plasma) processes
  • WAFER FABRICATION EQUIPMENT (WFE)

    the tools or machines used to manufacture integrated circuits
  • WAFER-LEVEL PACKAGING (WLP)

    a strategy for packaging integrated circuits while they are still part of the wafer; in contrast to conventional packaging methods, which first slice the wafer into dies and then package each die individually
  • WAFER-TO-WAFER UNIFORMITY

    a measure of the consistency in wafer processing results (such as etch profile) from one wafer to another; high uniformity is desirable
  • WET CLEAN

    the process of removing particles, contaminants, and/or other unwanted materials using liquid chemistries
  • WFE

  • WITHIN-WAFER UNIFORMITY

    a measure of the consistency in wafer processing results (such as film thickness) across a wafer; high uniformity is desirable
  • WLP

  • WORD LINE

    the path used to select all the memory cells in a row; connects the gates of the cells in a row that makes up a two-dimensional array

X

Y

  • YIELD

    the percentage or number of die that pass all testing and meet specified performance criteria (sometimes referred to as “good die”); high yield is desirable

Z

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