Glossary

This is a glossary of words you'll read and hear about semiconductors. Most of the words appear in this book, but many do not. They're included because you might come across them in other materials or in discussions with other people.

µ

Abbreviation for micron or micro. In the first sense, a micron is one-millionth of a meter, or about 1/25-thousandth of an inch. As the prefix micro-, it means one one-millionth of something. Finally, this is a letter in the Greek alphabet, pronounced “moo.”

Å

Abbreviation for angstrom, a unit of measure.

Angstrom

A unit of measure that's one-tenth of a nanometer, or about 1/250-millionth of an inch. A single atom is 3 to 10 angstroms across, depending on what material it is an atom of.

ASIC

Application-specific integrated circuit. An ASIC is a chip custom designed by one company for its own use in a specific product or for a specific purpose. ASICs are generally not made available for sale; only the company that designed them uses them. ASIC is pronounced “aay-sick.”

ASSP

Application-specific standard product. An ASSP is almost exactly the same as an ASIC, except that an ASSP is intended to be sold to outside companies. There are no technical or physical differences between an ASIC and an ASSP; the difference hinges purely on whether or not the chip will be sold.

Behavioral

A description of an HDL (hardware-design language) meaning that the description of the desired chip is not extremely detailed. Instead, a behavioral description describes how the chip should behave but does not define exactly how that behavior should be achieved. It's the responsibility of the HDL compiler to convert a behavioral description into a working chip design.

BiCMOS

A method of manufacturing semiconductors that combines bipolar and CMOS techniques. BiCMOS chips can be somewhat faster than CMOS chips but use more power and give off more heat. Pronounced as a three-syllable word, “bye-see-moss.”

Bin

A verb meaning to sort chips just after they're manufactured. Normal variations in manufacturing will cause some chips on a wafer to run faster or slower than others. The faster chips are usually sorted, or binned, and sold for a premium price. Conversely, the slower chips in the bin sort are often sold at a reduced price.

Binary

A system of counting that uses only two numbers, 0 and 1. People normally count using 10 numbers, from 0 through 9, which is called the decimal system. We count to 10 because we have 10 fingers, but there is nothing mathematically important or biologically “correct” about our habit of using 10 numbers. In electronics, it's much easier to have only two numbers that correspond to on and off. This is called the binary system. Binary arithmetic works the same as decimal arithmetic, but requires a lot of 1s and 0s to write big numbers.

Bipolar

A method of manufacturing semiconductors, or the type of chips made this way. Bipolar chips use more energy than CMOS chips but typically run faster. Bipolar processing techniques are often used to manufacture chips for high-end radio and television equipment.

Bit

A unit of measure, the smallest used in digital systems. In binary arithmetic a bit can be either 0 or 1. In electronics a bit is an electrical charge, either on or off. Depending on the context, a bit can be called 0 or 1, asserted or negated, true or false, high or low, off or on. The term was coined as a contraction of “binary digit.”

Byte

A unit of measure equal to 8 bits. Bytes are to bits what words are to letters of the alphabet. Because a single bit can represent only two numbers (i.e., 0 and 1) it takes several bits before you can do any reasonable math. The smallest collection of bits used is a byte. One byte can be rearranged in exactly 256 different combinations of bits (from 00000000 through 11111111), to represent the all the numbers from 0 to 255. Numbers larger than 255 require more bits, usually added eight at a time to make two bytes.

Circuit

A general term for any electronic design. Like water, electricity flows from its source to its final destination, and it might do useful work along the way, such as powering a steel mill. Eventually that electricity, like water, returns to its source, completing a circuit. Thus, all electronic designs, from tiny chips to large televisions, are called circuits.

CMOS

Abbreviation for complementary metal-oxide semiconductor. A dauntingly technical description of the process whereby most semiconductor chips are made. The CMOS process produces chips that consume less electricity and that give off less heat than other processes, such as bipolar (cf.) and BiCMOS (cf.). Pronounced like “sea-moss.”

CMP

Abbreviation for chemical-mechanical polishing, a method of smoothing the surface of a silicon wafer. Chemical-mechanical polishing is like sanding a mirror using very fine sandpaper. Silicon wafers are polished mirror-smooth before chips are etched onto them.

Compiler

A computer program for translating commands written in a computer programming language into binary patterns that a microprocessor can understand and execute. Compilers translate from one specific programming language to one specific type of microprocessor's instructions; they are not universal. Different compilers translate different languages.

Conductor

Any material that conducts electricity. Most kinds of metal, such as copper, steel, and aluminum, make good conductors.

CQFP

Ceramic quad flat pack. One of several types of physical packaging for finished chips. CQFP packages are similar to PLCC packages, but with a body of high-temperature ceramic material instead of plastic. CQFP packages are therefore more expensive than PLCCs of equivalent size and are reserved for high-energy chips that would melt a plastic package.

CVD

Abbreviation for chemical vapor deposition, a method of spraying dielectric material onto a silicon wafer before etching chips onto it.

Debugger

A computer program used by computer programmers to locate and remove accidental or unwanted behavior (“bugs”) from other computer programs. Debuggers, for instance, allow the programmer to run the computer program very slowly to observe its behavior in something approaching human-perceptible speed.

Decimal

A system of counting that uses 10 numbers, from 0 to 9; in other words, the normal number system. Decimal is different from the binary system, which uses only two numbers.

Defect

A flaw in a chip, usually caused when dirt or dust lands on the wafer while it's being processed. The number of defects divided by the size of the wafer is called the defect density.

Dice

Plural of die; bare silicon chips before they are put into plastic or ceramic packages. Dice are very thin and shiny; they are the actual “chip” in semiconductor chips.

Die

A bare chip; the small rectangular piece of silicon after it has had an electronic circuit etched onto it but before it is placed in a plastic or ceramic package. A die (the plural form is dice) is a fully functional electronic device, or chip. It needs only a protective package before it can be handled and sold. In certain cases, vendors might sell a bare die (called known-good die, or KGD) if the customer is equipped to handle unpackaged chips without contaminating them.

Dielectric

A spacer between two electrical components. In capacitors and transistors, the dielectric is an extremely thin layer of material between two layers of metal or silicon. The dielectric acts as a barrier to the electrical flow.

DIL

Dual in-line. A synonym for DIP, which is one of several types of plastic or ceramic packages used for finished chips.

DIP

Dual in-line package. One of several types of package for finished chips. Rectangular DIP packages are made of either black plastic or brown ceramic material, with two parallel rows of metal legs emerging from the long sides. The metal legs, called pins, are the electrical contacts between the outside world and the chip buried inside. Small DIP packages have eight pins (four on each side), whereas large ones might have as many as 68 pins, making them very long and narrow. DIP packages aren't good for very big chips because it would make them too long and fragile. The pins on a DIP package are spaced exactly 0.10-inch (one-tenth of an inch) apart. Pronounced as a single word, “dip.”

Doping

Pure silicon can be “doped,” or mixed, with materials such as selenium to make it a better semiconductor for building transistors.

Download

To transfer data, usually from a distant place or computer to a local place or computer. “Download” is like “bring” because it implies that the object is moving toward the user.

DRAM

Dynamic random-access memory. One of the two major types of RAM, the other being static RAM. The “dynamic” qualifier means these chips can only “remember” data for a few thousandths of a second, so they need to be refreshed at regular intervals. The refresh process also makes DRAM chips consume more electricity than SRAM chips. Finally, DRAM chips are slower than SRAM chips when retrieving the data they have stored. The one great advantage DRAMs have over SRAMs is capacity. DRAMs can store about four times more data per square millimeter of silicon than SRAMs, making them more economical for most uses. Pronounced as a two-syllable word, “dee-ram.”

ECL

Emitter-coupled logic. A particular way of combining transistors when designing chips. ECL chips are rare but tend to be very fast.

EDA

Abbreviation for electronic design automation, a term that describes the business of automating the design of electronic products. Several companies sell EDA software and tools that help engineers design, test, simulate, and fabricate new chips. Pronounced as individual letters, “ee-dee-ay.”

Embedded

A blanket term to describe any chip not associated with personal computers. In other words, everything except PCs is an embedded product. This term is most often used with microprocessors, as in “embedded microprocessor for automotive systems.”

Fab

A verb meaning to build a chip and also a noun for the place where you make chips. A fab is a chip-making factory. More subtly, a fab is a factory owned by a large chip company for its own use, as opposed to a foundry.

FET

Field-effect transistor. One of a few special classes of transistors that can be purchased by itself in a very small package. Pronounced as individual letters, “eff-ee-tee.”

Flash

A type of nonvolatile memory chip. Flash memories can be electrically erased in a few seconds and loaded with new data in less than a minute. This process is so much faster than the previous generation of EEPROM chips that they earned the name flash memory chips.

Foundry

A chip-manufacturing plant that is operated for the benefit of several client companies; a factory-for-hire. Foundries are distinct from fabs, which are company-owned manufacturing plants for in-house use.

FR-4

The fiberglass material normally used to make printed-circuit boards.

Gate

A basic unit of digital electronics. Gates perform very simple logic functions, such as the AND, OR, and XOR functions. A second meaning of gate is one of the three contact points on a semiconductor transistor.

GB

Abbreviation for gigabyte, or 1,073,741,824 (roughly 1 billion) bytes. With a lowercase b (Gb), it usually means gigabits, a quantity eight times smaller. Beware; not all publications are consistent about this usage.

Gigahertz

One billion cycles or operations per second. Most chips operate at a fixed, regular speed, like the steady beat of a drummer in a band. These beats are measured in units called hertz; a gigahertz is 1 billion beats per second.

HDL

Hardware-description language or high-level design language. A blanket term that covers any language used by a chip designer to describe how a new chip should operate. An HDL compiler will then convert the HDL description into real gates and transistors.

Hertz

A unit of measure, in cycles per second. Similar to RPM, hertz measures how fast something spins around or repeats itself. The word comes from the name of scientist Heinrich Hertz, and has been used for decades to measure the frequency of radio waves, visible light, and other electromagnetic phenomena.

Insulator

Any material that does not conduct electricity. Rubber and plastic are good insulators, which is why they're used on the outside of most electrical products, cords, and plugs.

IP

Intellectual property or Internet Protocol (the two terms are unrelated). In the first sense, IP is a broad term that covers patents, trademarks, copyrights, trade secrets, know-how, and other valuable but intangible assets. The term was popularized in the late 1990s when several semiconductor firms switched from making chips to simply licensing the design of those chips—their intellectual property—to other companies. In that sense, IP licensing is similar in concept to franchising restaurant chains. In its second sense, IP refers to the Internet Protocol, a de facto standard system of communication among computers that is used, obviously, for the Internet as well as in other types of networks. Most often found in the abbreviation TCP/IP.

ITRS

International Technology Roadmap for Semiconductors. A report generated every year or so by the Semiconductor Industry of America that projects what manufacturing trends and advancements will occur in the next few years.

KB

Abbreviation for kilobyte, or 1,024 bytes. With a lowercase b (Kb) it usually means kilobits, a quantity eight times smaller. Beware; not all publications are consistent about this usage.

KGD

Known-good die. Individual silicon chips (die) that have been tested and are guaranteed to be in good working order before being inserted into plastic or ceramic packages. Some large-volume companies prefer to buy KGD instead of normally packaged chips to save space and weight.

Kilohertz

One thousand cycles or operations per second. Most chips operate at a fixed, regular speed, like the steady beat of a drummer in a band. These beats are measured in units called hertz; a kilohertz is 1,000 beats per second.

Kludge

A made-up word for something that's hastily prepared, inelegant, and probably unreliable. The ultimate insult among engineers. Kludge can be used as a noun (“that's a kludge”) or a verb (“let's just kludge something together for the investors”). Pronounced “klooj.”

LED

Light-emitting diode. A small light, usually red, made using semiconductor materials and techniques. LEDs also come in yellow, green, and more recently, blue. Pronounced as individual letters, “ell-ee-dee.”

LSI

Large-scale integration. Part of a series of vague descriptions of the level of complexity on a chip. LSI ranks near the bottom of this series, above SSI but below VLSI and ULSI. The term has no precise meaning or qualifications.

MB

Abbreviation for megabyte, or 1,048,576 bytes. With a lowercase b (Mb) it usually means megabits, a quantity eight times smaller. Beware; not all publications are consistent about this usage.

Megahertz

One million cycles or operations per second. Most chips operate at a fixed, regular speed, like the steady beat of a drummer in a band. These beats are measured in units called hertz; a megahertz is 1 million beats per second.

MEMS

Micro electrical-mechanical sensor. Any of a class of tiny devices that are mechanical in nature but built using semiconductor materials and techniques. Pronounced “mems,” even when there's only one.

Micron

A unit of measure equal to one one-millionth of a meter, or about one-25,000th of an inch. Transistors on today's semiconductor chips are much smaller than one micron.

MIPS

Millions of instructions per second. A measure of how quickly a microprocessor or computer processes its software instructions. An ineffective measure of performance, however, because different microprocessors process different kinds of instructions. Note for the pedantic: MIPS is singular, not plural, so the S should always be capitalized and always spoken, even when there is only one.

Moore's Law

A casual observation made by industry executive Gordon Moore in 1965, and revised in 1975, that has since become a de facto “law” for estimating progress in the semiconductor industry. Moore observed that the semiconductor industry in general seemed to need only about 18 months to find ways to double the number of transistors they could squeeze onto a silicon chip. This continual shrink in transistor size, and the resulting increase in chip speed and complexity, has become known as Moore's Law.

MOS

Metal-oxide semiconductor. A term describing the chemistry used in the most popular type of semiconductor manufacturing, including the popular CMOS (complimentary metal-oxide semiconductor) process. Pronounced like “moss.”

MSI

Medium-scale integration. Part of a series of vague descriptions of the level of complexity on a chip. MSI ranks near the bottom of this series, above SSI, but below LSI, VLSI, and ULSI. The term has no precise meaning or qualifications.

Nanoacre

A facetious measurement of space or area, sometimes used to brag about how densely packed a chip is, as in “this chip has a million transistors per nanoacre.” A nanoacre is technically one-billionth of an acre, or about one one-hundredth of a square inch, but the term is not used in its literal sense.

Nanometer

One-billionth of a meter or one-thousandth of a micron. One nanometer is about 0.0000000394 of an inch. Modern semiconductor transistors are approximately 100 nanometers across, and getting smaller.

Netlist

An electrical circuit diagram or a blueprint for designing a chip or other electronic product. Wires with components connected to them are called nets and the list of all the nets is, naturally, the netlist.

NIH

Not invented here. An attitude that anything created by outsiders is inferior to anything created by oneself or one's employer. Chauvinism.

Nm

Abbreviation for nanometer (one-billionth of a meter). A nanometer is 1,000 times smaller than a micron, or about 0.0000000394 of an inch.

Nonvolatile

A type of memory chip that retains its data even after power is turned off. Most ROM chips are nonvolatile.

PC board

Printed circuit board, often shortened to PCB.

PCB

Printed circuit board. A fiberglass board (usually green) with copper wires, or traces, imprinted onto it.

Pin

The metal “leg” that sticks out of a packaged chip. The pins are internally connected by wires to the silicon chip inside the chip's plastic or ceramic package.

PLCC

Plastic leaded chip carrier. One of several types of physical packaging for finished chips. PLCC packages are square and flat, with a row of metal pins along all four edges that serve as the electrical contacts into and out of the chip. The package material is plastic, by definition; ceramic versions are called CLCC. PLCC packages might have from 28 pins (seven along each side) to a few hundred pins. The pins on a PLCC package are generally curled under in a J-form, suitable for surface-mounting.

Port

A verb meaning to convert, adjust, or modify a computer program (software) that runs on one type of computer so that it runs on another type of computer. Porting might be a simple task or it can be very complex and involved, taking more time and effort than it did to create the original program.

Printed circuit board

A green fiberglass material used to connect individual chips together, both electrically and mechanically. The fiberglass is an insulator (it does not conduct electricity) but the PCB is embedded with copper wires (which do conduct electricity). The fiberglass board serves as a flat mechanical mounting structure for chips and other components. The copper wires buried in the fiberglass conduct electricity between these components. The arrangement of the copper wires (or “traces”) within the board is key, and determines how the components are wired together. PCBs are generally green in color, with the copper clearly visible on the surface or buried within the layers of the material. Multilayer PCBs are common, with several layers of fiberglass and copper sandwiched together to provide more conductive paths for more complex circuits.

RAM

Random-access memory. One of two major classifications of memory chips, the other being ROM. RAMs are so called because they can retrieve any data they contain, in random order, without regard to where that data is stored within the chip. In other words, the data does not have to be accessed sequentially, like videotape. The term RAM also implies, albeit indirectly, that data can be both written to, and read from, the chip. This distinguishes them from ROMs, which cannot store new data, but only retrieve what data already exists in the chip. The two major subclassifications of RAM are DRAM and SRAM. Pronounced just like the word for a male goat: “ram.”

Real-time

A type of computer or computer program that responds to events in the real, physical world of humans. For instance, a computer that controls the elevators in a tall office building is a real-time computer, but a computer printing checks in a bank is not. Real-time systems must respond quickly to events as they happen; they cannot postpone processing to a more convenient (for the computer) moment. They must be aware of “real” time to avoid annoying or harming humans.

ROM

Read-only memory. One of two major classifications of memory chips, the other being RAM. ROMs differ from RAMs because they cannot store new data; they can only supply the data they were given during manufacturing or initial programming. ROMs are like stone tablets dried in the sun. Attempting to electronically write new data into a ROM chip will not harm it; the new data is simply ignored. ROM chips are economical where large amounts of permanent storage are required, such as video games, automotive engine control systems, or electronic books. Pronounced as a single word, “rom.”

RTL

Register-transfer level. A description of a type of HDL (hardware-description language), meaning it describes the desired hardware down to the level of individual registers in the chip. An RTL-level description is a detailed description of a chip. A less detailed use of HDL would be a behavioral description.

RTOS

Real-time operating system. A computer operating system that programs a computer to respond to events in real time (cf.). Microsoft Windows, MacOS, UNIX, and Linux are not real-time operating systems; those computers handle tasks as they see fit, in no particular order. A real-time operating system schedules tasks in a predictable and reliable manner, and guarantees that certain time-critical tasks (e.g., stopping a moving subway train at the station platform) will not be postponed.

Schematic

A diagram of an electrical circuit. Similar to blueprints, schematics show where each component and wire is located. Schematics provide a map of an electrical device.

SDRAM

Synchronous dynamic random-access memory. A subtype of DRAM that uses a synchronous method of communicating with other chips. SDRAMs are neither faster nor slower than other types of DRAMs, nor do they store more or less data. Their only difference lies in their communication method with other chips. Pronounced as a three-syllable word, “ess-dee-ram.”

Semiconductor

Any material that conducts electricity, but not particularly well. The most popular and well-known semiconductor is silicon. Semiconductors can be natural or artificial; silicon is a natural substance. Semiconductors are valuable because of their ability to change between a conductive and nonconductive state, making electrical switches.

SIA

Semiconductor Industry Association. A nonprofit organization that conducts research on behalf of the worldwide semiconductor industry as a whole.

Silicon

A natural substance found in soil, especially in sand. Silicon is a natural semiconductor; it conducts electricity but not well. Silicon is refined and processed to produce semiconductor chips. Pronounced “SILL-uh-conn.”

Silicon Valley

The general area around Santa Clara County in California. This 40-mile stretch alongside San Francisco Bay is home to most of the world's semiconductor companies. Silicon Valley is a notional concept; it's only a nickname so it has no official borders. Generally speaking, the Valley reaches from San Jose in the south to approximately Redwood City in the north, or roughly the boundaries of Santa Clara County. Journalist Don Hoefler coined the name in a 1971 article that appeared in Electronic News.

Silicone

An artificial substance used in cosmetic surgery and as a household sealer and lubricant. Silicone is waxy and can be molded into various shapes, making it useful as weather stripping. Silicone is not related to silicon. Pronounced “sill-uh-CONE.”

SIP

Single in-line package. Similar to a DIP package but with only a single row of metal pins. SIPs are used for very small or simple chips that don't need more than a few pins. SIPs can stand upright on a printed circuit board, making them very space-efficient.

SMT

Surface-mount technology. An abbreviation for any chip or printed circuit board that uses surface-mounted components.

Solder

A mixture of lead and tin, two very soft metals that share two useful characteristics: They both conduct electricity and they both melt at low temperatures. Solder therefore makes a good conductive “glue” for attaching wires to chips or chips to boards. Solder is both a noun and a verb and is pronounced “saw-der.”

Solid state

An out-of-date term first used to described semiconductors, as opposed to vacuum tubes. Semiconductors are solid materials, like silicon, with no moving parts. Vacuum tubes, on the other hand, were fragile and had many delicate internal components.

SRAM

Static random-access memory. One of two major types of RAM, the other being dynamic RAM. These chips are “static” because they do not need to be refreshed like DRAM chips do. They hold their storage for as long as the power is on. SRAMs are more energy efficient than DRAMs, and are also faster. These qualities makes SRAMs the memory of choice for both high-performance systems and low-power systems. The major disadvantage of SRAMs is their cost; they store only one-quarter the amount of data compared to DRAMs, making DRAMs cheaper where large quantities of memory are required. Pronounced as a two-syllable word, “ess-ram.”

SSI

Small-scale integration. Part of a series of vague descriptions of the level of complexity on a chip. SSI ranks at the bottom of this series, below MSI, LSI, VLSI, and ULSI. The term has no precise meaning or qualifications.

Surface-mount

A method of soldering chips to a printed circuit board without drilling holes in the board for the chip's pins. Surface-mounted chips have their pins curled in a J pattern so they can be soldered to the top or bottom of a PC board.

Trace

A copper wire buried in a printed circuit board. A trace is a thin, flat wire embedded into or etched onto a layer of fiberglass for the purpose of conducting electricity between two or more components soldered on the board. Each layer of a printed circuit board will have several such traces, but the traces cannot cross each other. Even simple printed circuit boards have traces on both sides, running north to south on one side and east to west on the other side. Complex printed circuit boards will sandwich multiple layers together to increase the density of traces and improve opportunities for interconnection among components.

ULSI

Ultra large-scale integration. Part of a series of vague descriptions of the level of complexity on a chip. ULSI ranks at the top of this series, above SSI, MSI, LSI, and VLSI. The term has no precise meaning or qualifications.

Upload

To transfer data, usually from a local place or computer to a distant place or computer. “Upload” is like “send” and implies that the object is moving away from the user.

Verilog

One of two very popular hardware-design languages (HDLs) used to design new chips.

VHDL

Very high-level design language. One of two very popular hardware-design languages (HDLs) used to design new chips.

Via

A small copper-plated hole in a printed circuit board used to join traces from opposite sides of the board. When it's desirable to connect a copper trace on the top of a PC board to another copper trace on the bottom of a PC board, a hole is drilled through the board and plated with copper. These vias are the only place that copper traces travel vertically through the thickness of the PC board. Several vias might be required for a trace to negotiate a crowded PC board to a trace on the opposite side. Vias generally penetrate all layers of a multilayer PC board; holes drilled only partway through are called “blind vias.”

VLIW

Very long instruction word. A type of computer or microprocessor architecture or design. A VLIW computer's instructions are very long in comparison to the more common 16-bit or 32-bit instructions used by contemporary microprocessors. VLIW instructions might be 128 bits or 512 bits long, for example. The purpose of VLIW is to get multiple instructions into the microprocessor at once. Pronounced as individual letters.

VLSI

Very large-scale integration. Part of a series of vague descriptions of the level of complexity on a chip. VLSI ranks near the top of this series, above SSI, MSI, and LSI, but below ULSI. The term has no precise meaning or qualifications.

Volatile

A type of memory chip that loses its data when power is turned off. All DRAM and SRAM chips are volatile.

Wafer

The round, flat “pancake” of silicon used to make chips. Wafers are thin, shiny slices cut from an ingot of pure silicon. The size of a wafer depends on the diameter of the ingot from which it is cut, but 6 to 8 inches (200 to 300 mm) is standard. Wafers have a characteristic flat spot on one side as an aid to the automated chip-handling equipment.

Wafer start

The act of beginning to process a wafer of silicon to make chips. The productivity of a fab or foundry can be measured in wafer starts per week.

WSI

Wafer-scale integration. The process of using an entire silicon wafer to create one gigantic chip. WSI was explored in the 1980s as the next step beyond VLSI and ULSI integration. Rather than assemble chips on a PC board, WSI would assemble them while still at the bare-die stage. WSI never caught on, largely because of cost, complexity, and the enormous waste if any part of the chip was found to be faulty.

Yield

The number of working chips out of the total number of chips manufactured, usually expressed as a percentage. In even the best fabs and foundries, some chips will fail final inspection and be discarded. The percentage of chips that work is called the yield percentage. Yields improve over time as the semiconductor vendor gains experience with the product. Mature chips might yield at 97 percent or better; early prototypes might yield fewer than 20 percent good chips.