Semiconductor Glossary

Mainframe: The main unit of a computer that houses such components as the CPU, main memory, channel controller, and memory controller. Mainframe often refers to a large general-purpose computer, which was dominant in the 1970s and early 1980s. Subsequently, mainframes gave way to workstations and Intel architecture-based personal computers.

Micro-Controller Unit: A type of LSI that integrates four basic elements of a microcomputer (data I/O, data processing, program memory [ROM], and data memory [RAM] units) on a single chip. In larger computing systems, the first two elements are combined in microprocessor units or MPUs, and ROM and RAM are provided as separate devices. MPUs are typically used for personal computers.

Micro Electro Mechanical System: The technology that enables microscopic devices with electro-mechanical systems. MEMS devices have minuscule moving parts that are built within a chip using semiconductor processing technologies. The diverse functions enabled by these moving parts give MEMS wide-ranging applications (e.g., accelerometers, gyroscopes, and so on).

Microprocessor: A single LSI chip that is functionally analogous to the central processing unit of a large computer. A microprocessor performs various operations and controls.

Moore's Law: A rule of thumb that the number of transistors in a large-scale integrated circuit would double every 18 months or so. This observation was made by Gordon Moore in 1965, who later co-founded Intel and became its chairman (now retired). In reality, the integration level has doubled every 24 months, but the pace of chip scaling is slowing lately.

Metal-Oxide-Semiconductor Field-Effect Transistor: A type of field-effect transistor (FET) that has the structure of a metal-oxide semiconductor (MOS). It is the most common transistor type in LSIs today. A MOSFET consists of a silicon substrate covered with a dielectric oxide film, on which a patterned conductive metal layer is deposited. When a voltage is applied to the gate terminal on top of the metal layer, electric current flows underneath the dielectric film.

Magnetoresistive Random Access Memory: A random access memory technology with a memory cell structure that uses magnetoresistive elements instead of DRAM capacitors. The magnetoresistive element consists of two magnetic layers (one is pinned and the other is free) separated by a non-magnetic barrier. The resistivity of the element changes depending on the spin direction of the free-moving layer. Either numerical value 0 or 1 is assigned to each cell according to its resistivity change status, enabling data to be stored and read. Because an MRAM stores the data magnetically, it is non-volatile and requires no electricity to maintain data.

Multi-Chip Module (MCM): An electronic assembly integrating a number of bare chips, including a CPU and peripheral logic devices, on a substrate. Because MCMs can be built by putting proven bare chips together, they take less time to package than SOCs. MCMs are often used for mobile phones that require high integration levels with very short development lead times.

Multi-Core MPU: A microprocessor unit (MPU) with two or more processing units called cores. The multi-core design allows faster operations while saving power.

N-Type Semiconductor (Negative Semiconductor): In n-type semiconductors, free electrons move when a voltage is applied, carrying negative charge to produce an electric current. N-type semiconductors are created by doping quadrivalent elements (such as silicon and germanium) with trace amount of pentavalent elements (such as arsenic).

NAND Type Flash Memory: A type of non-volatile memory medium invented in 1987 by Fujio Masuoka (then a Toshiba employee). Compared to the NOR type flash memory, NAND flash is smaller in circuit scale, less costly, and offers larger capacities as well as faster read/write speeds. NAND flash is widely used for USB drives, memory cards for digital cameras, and storage devices for mobile phones and digital music players. As conventional chip scaling technology is reaching its limits, 3D structures have been introduced in flash memory devices in recent years.

Nano Imprint: A lithography technology for nanoscale pattern transference, which is attained by pressing a mold with predefined nanopatterns onto a substrate coated with a polymer film. The technology is attracting attention for its low cost and ease of volume manufacturing.

NOR Type Flash Memory: A type of non-volatile memory medium invented in 1984 by Fujio Masuoka (then a Toshiba employee). In 1988, Intel commercially released the first NOR type flash memory device. Compared to the NAND type flash memory, NOR flash is faster in read operations and superior in random accessibility, while its integration level and write speed are inferior. NOR flash is principally used in microcontrollers and as a firmware storage chip for devices that require high reliability but do not support hard disk drives, including routers, printers, digital cameras, GPS navigation systems, car electronics, and mobile phones.