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In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term memory is often synonymous with the term primary storage or main memory. An archaic synonym for memory is store.
The metal–oxide–semiconductor field-effect transistor, also known as the metal–oxide–silicon transistor, is a type of insulated-gate field-effect transistor that is fabricated by the controlled oxidation of a semiconductor, typically silicon. The voltage of the gate terminal determines the electrical conductivity of the device; this ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals.
Static random-access memory is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed.
Dynamic random-access memory is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxide-semiconductor (MOS) technology. While most DRAM memory cell designs use a capacitor and transistor, some only use two transistors. In the designs where a capacitor is used, the capacitor can either be charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. The electric charge on the capacitors gradually leaks away; without intervention the data on the capacitor would soon be lost. To prevent this, DRAM requires an external memory refresh circuit which periodically rewrites the data in the capacitors, restoring them to their original charge. This refresh process is the defining characteristic of dynamic random-access memory, in contrast to static random-access memory (SRAM) which does not require data to be refreshed. Unlike flash memory, DRAM is volatile memory, since it loses its data quickly when power is removed. However, DRAM does exhibit limited data remanence.
Robert Dennard is an American electrical engineer and inventor.
Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retain stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data.
Volatile memory, in contrast to non-volatile memory, is computer memory that requires power to maintain the stored information; it retains its contents while powered on but when the power is interrupted, the stored data is quickly lost.
Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to MOS memory, where data is stored within metal–oxide–semiconductor (MOS) memory cells on a silicon integrated circuit memory chip. There are numerous different types using different semiconductor technologies. The two main types of random-access memory (RAM) are static RAM (SRAM), which uses several MOS transistors per memory cell, and dynamic RAM (DRAM), which uses a MOS transistor and a MOS capacitor per cell. Non-volatile memory uses floating-gate memory cells, which consist of a single floating-gate MOS transistor per cell.
A fin field-effect transistor (FinFET) is a multigate device, a MOSFET built on a substrate where the gate is placed on two, three, or four sides of the channel or wrapped around the channel, forming a double or even multi gate structure. These devices have been given the generic name "FinFETs" because the source/drain region forms fins on the silicon surface. The FinFET devices have significantly faster switching times and higher current density than planar CMOS technology.
Ferroelectric RAM is a random-access memory similar in construction to DRAM but using a ferroelectric layer instead of a dielectric layer to achieve non-volatility. FeRAM is one of a growing number of alternative non-volatile random-access memory technologies that offer the same functionality as flash memory. An F-RAM chip contains a thin film of ferroelectric material, often lead zirconate titanate, commonly referred to as PZT. The atoms in the PZT layer change polarity in an electric field, thereby producing a power-efficient binary switch. However, the most important aspect of the PZT is that it is not affected by power disruption or magnetic interference, making F-RAM a reliable nonvolatile memory.
The floating body effect is the effect of dependence of the body potential of a transistor realized by the silicon on insulator (SOI) technology on the history of its biasing and the carrier recombination processes. The transistor's body forms a capacitor against the insulated substrate. The charge accumulates on this capacitor and may cause adverse effects, for example, opening of parasitic transistors in the structure and causing off-state leakages, resulting in higher current consumption and in case of DRAM in loss of information from the memory cells. It also causes the history effect, the dependence of the threshold voltage of the transistor on its previous states. In analog devices, the floating body effect is known as the kink effect.
The 22 nm node is the process step following 32 nm in CMOS MOSFET semiconductor device fabrication. The typical half-pitch for a memory cell using the process is around 22 nm. It was first demonstrated by semiconductor companies for use in RAM memory in 2008. In 2010, Toshiba began shipping 24 nm flash memory chips, and Samsung Electronics began mass-producing 20 nm flash memory chips. The first consumer-level CPU deliveries using a 22 nm process started in April 2012 with the Intel Ivy Bridge processors.
A multigate device, multi-gate MOSFET or multi-gate field-effect transistor (MuGFET) refers to a metal–oxide–semiconductor field-effect transistor (MOSFET) that has more than one gate into a single device. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor (MIGFET). The most widely used multi-gate devices are the FinFET and the GAAFET, which are non-planar transistors, or 3D transistors.
Fujio Masuoka is a Japanese engineer, who has worked for Toshiba and Tohoku University, and is currently chief technical officer (CTO) of Unisantis Electronics. He is best known as the inventor of flash memory, including the development of both the NOR flash and NAND flash types in the 1980s. He also invented the first gate-all-around (GAA) MOSFET (GAAFET) transistor, an early non-planar 3D transistor, in 1988.
Random-access memory is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media, where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.
Z-RAM is a tradename of a now-obsolete dynamic random-access memory technology that did not require a capacitor to maintain its state. Z-RAM was developed between 2002 and 2010 by a now-defunct company named Innovative Silicon.
The memory cell is the fundamental building block of computer memory. The memory cell is an electronic circuit that stores one bit of binary information and it must be set to store a logic 1 and reset to store a logic 0. Its value is maintained/stored until it is changed by the set/reset process. The value in the memory cell can be accessed by reading it.
A ferroelectric field-effect transistor is a type of field-effect transistor that includes a ferroelectric material sandwiched between the gate electrode and source-drain conduction region of the device. Permanent electrical field polarisation in the ferroelectric causes this type of device to retain the transistor's state in the absence of any electrical bias.
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of insulated-gate field-effect transistor (IGFET) that is fabricated by the controlled oxidation of a semiconductor, typically silicon. The voltage of the covered gate determines the electrical conductivity of the device; this ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. The MOSFET was invented by Egyptian engineer Mohamed M. Atalla and Korean engineer Dawon Kahng at Bell Labs in 1959. It is the basic building block of modern electronics, and the most frequently manufactured device in history, with an estimated total of 13 sextillion (1.3 × 1022) MOSFETs manufactured between 1960 and 2018.
References
- ↑ Noel Rodriguez, Sorin Cristoloveanu and Francisco Gamiz (5 October 2009). "A-RAM: Novel capacitor-less DRAM memory". 2009 International SOI Conference. IEEE. doi:10.1109/SOI.2009.5318734.
- ↑ Noel Rodriguez, Sorin Cristoloveanu and Francisco Gamiz (September 2010). "A-RAM Memory Cell: Concept and Operation". Electron Device Letters. IEEE: 972–974. doi:10.1109/LED.2010.2055531.
- ↑ Patent number: FR09/52453, "Point mémoire RAM à un transistor", Institut National de la Propriété Industrielle
- ↑ Peter Clarke (19 October 2010). "France's CNRS offers nano-memory IP". EE Times. Retrieved 30 September 2016.
- ↑ "A-RAM: The Advanced DRAM Substitute". Web site. University of Granada. 2010. Archived from the original on 18 May 2013. Retrieved 30 September 2016.
- ↑ University of Granada (22 November 2012). "Scientists design a revolutionary data storage device". Science Daily news release. Retrieved 30 September 2016.