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Semiconductor

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Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. Developments in quantum physics in turn led to the development of the transistor in 1947, the integrated circuit in 1958, and the MOSFET (metal–oxide–semiconductor field-effect transistor) in 1959.

In certain semiconductors, excited electrons can relax by emitting light instead of producing heat. These semiconductors are used in the construction of light-emitting diodes and fluorescent quantum dots. Quantum dots (QDs) are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from larger particles due to quantum mechanics.

Semiconductors with high thermal conductivity can be used for heat dissipation and improving thermal management of electronics. Semiconductors have large thermoelectric power factors making them useful in thermoelectric generators, as well as high thermoelectric figures of merit making them useful in thermoelectric coolers.

Semiconductors for ICs are mass-produced. To create an ideal semiconducting material, chemical purity is paramount. Any small imperfection can have a drastic effect on how the semiconducting material behaves due to the scale at which the materials are used. A high degree of crystalline perfection is also required, since faults in the crystal structure interfere with the semiconducting properties of the material. Crystalline faults are a major cause of defective semiconductor devices. The larger the crystal, the more difficult it is to achieve the necessary perfection. Current mass production processes use crystal ingots between 100 and 300 mm (3.9 and 11.8 in) in diameter which are grown as cylinders and sliced into wafers.

The conductivity of semiconductors may easily be modified by introducing impurities into their crystal lattice. The process of adding controlled impurities to a semiconductor is known as "doping". The amount of impurity, or dopant, added to an intrinsic (pure) semiconductor varies its level of conductivity. Doped semiconductors are referred to as extrinsic. By adding impurity to the pure semiconductors, the electrical conductivity may be varied by factors of thousands or millions.

In the late 1950s, Mohamed Atalla utilized his surface passivation and thermal oxidation methods to develop the metal–oxide–semiconductor (MOS) process, which he proposed could be used to build the first working silicon field-effect transistor. The CMOS (complementary MOS) process was developed by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. The "complimentary" part of CMOS refers to the two different types of semiconductors each transistor contains — N-type and P-type. FinFET (fin field-effect transistor), a type of 3D multi-gate MOSFET, was developed by Digh Hisamoto and his team of researchers at Hitachi Central Research Laboratory in 1989.

The semiconductor industry is the aggregate of companies engaged in the design and fabrication of semiconductors. It formed around 1960, once the fabrication of semiconductor devices became a viable business. The industry's annual semiconductor sales revenue has since grown to over $481 billion, as of 2018. The semiconductor industry is in turn the driving force behind the wider electronics industry, with annual power electronics sales of £135 billion ($216 billion) as of 2011, annual consumer electronics sales expected to reach $2.9 trillion by 2020, tech industry sales expected to reach $5 trillion in 2019, and e-commerce with over $29 trillion in 2017.

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Power electronics is the branch of electrical engineering that deals with the processing of high voltages and currents to deliver power that supports a variety of needs. From household electronics to equipment in space applications, these areas all need stable and reliable electric power with the desired specifications.

The most widely used semiconductor device is the MOSFET (metal-oxide-semiconductor field-effect transistor, or MOS transistor). MOSFET scaling and miniaturization has been the primary factor behind the rapid exponential growth of semiconductor technology since the 1960s. The MOSFET, which accounts for 99.9% of all transistors, is the driving force behind the semiconductor industry and the most widely manufactured device in history, with an estimated total of 13 sextillion (1.3 × 1022) MOSFETs having been manufactured between 1960 and 2018.

The global semiconductor industry is dominated by companies from the Asia-Pacific region. The industry is based on the foundry model, which consists of semiconductor fabrication plants (foundries) and integrated circuit design operations, each belonging to separate companies or subsidiaries. Some companies, known as integrated device manufacturers, both design and manufacture semiconductors. The foundry model has resulted in consolidation among foundries. As of 2021, only three firms are able to manufacture the most advanced semiconductors. Part of this is due to the high capital costs of building foundries. TSMC's latest factory, capable of fabricating 3 nm process semiconductors and completed in 2020, cost $19.5 billion.

Semiconductor sales (2017)

Integrated device manufacturers (IDMs) design and manufacture integrated circuits. Many companies, known as fabless semiconductor companies, only design devices; merchant or pure play foundries only manufacture devices for other companies, without designing them. Largest companies: Samsung (IDM), Intel (IDM), SK Hynix (IDM), TSMC (Pure-play), Micron (IDM), Broadcom (Fabless), Qualcomm (Fabless), Toshiba (IDM), TI (IDM), Nvidia (Fabless).

The transistor count is the number of transistors in an electronic device. It typically refers to the number of MOSFETs (metal-oxide-semiconductor field-effect transistors, or MOS transistors) on an integrated circuit (IC) chip, as all modern ICs use MOSFETs. It is the most common measure of IC complexity (although the majority of transistors in modern microprocessors are contained in the cache memories, which consist mostly of the same memory cell circuits replicated many times). The rate at which MOS transistor counts have increased generally follows Moore's law, which observed that the transistor count doubles approximately every two years.

Since 2009, however, "node" has become a commercial name for marketing purposes that indicates new generations of process technologies, without any relation to gate length, metal pitch or gate pitch. For example, GlobalFoundries' 7 nm processes are similar to Intel's 10 nm process, thus the conventional notion of a process node has become blurred. TSMC and Samsung's 10 nm processes are somewhere between Intel's 14 nm and 10 nm processes in transistor density. The transistor density (number of transistors per square millimetre) is more important than transistor size, since smaller transistors no longer necessarily mean improved performance, or an increase in the number of transistors.

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来源： https://www.cnblogs.com/funwithwords/p/16582905.html