Planar process

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Annotated die photo of a Fairchild chip 74LS244 F 8314 annotated sm.jpg
Annotated die photo of a Fairchild chip

The planar process is a manufacturing process used in the semiconductor industry to build individual components of a transistor, and in turn, connect those transistors together. It is the primary process by which silicon integrated circuit chips are built. The process utilizes the surface passivation and thermal oxidation methods.

Semiconductor industry companies manufacturing semiconductor devices

The semiconductor industry is the aggregate collection 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 revenue has since grown to $412.2 billion in 2017.

Transistor Basic electronics component

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

Silicon Chemical element with atomic number 14

Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard and brittle crystalline solid with a blue-grey metallic lustre; and it is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, and lead are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its melting and boiling points of 1414 °C and 3265 °C respectively are the second-highest among all the metalloids and nonmetals, being only surpassed by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. More than 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust after oxygen.

Contents

The planar process was developed at Fairchild Semiconductor in 1959 by Jean Hoerni, who adopted the surface passivation and thermal oxidation methods originally developed by Mohamed Atalla at Bell Labs in 1957. Hoerni's planar process was in turn the basis for Robert Noyce's invention of the monolithic integrated circuit chip at Fairchild, later in 1959.

Fairchild Semiconductor American company

Fairchild Semiconductor International, Inc. was an American semiconductor company based in San Jose, California. Founded in 1957 as a division of Fairchild Camera and Instrument, it became a pioneer in the manufacturing of transistors and of integrated circuits. Schlumberger bought the firm in 1979 and sold it to National Semiconductor in 1987; Fairchild was spun off as an independent company again in 1997. In September 2016, Fairchild was acquired by ON Semiconductor.

Jean Amédée Hoerni was a Swiss-American engineer. He was a silicon transistor pioneer, and a member of the "traitorous eight". He developed the planar process, an important technology for reliably fabricating and manufacturing semiconductor devices, such as transistors and integrated circuits.

Bell Labs Research and scientific development company

Nokia Bell Labs is an industrial research and scientific development company owned by Finnish company Nokia. With headquarters located in Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. Bell Labs has its origins in the complex past of the Bell System.

Overview

The key concept is to view a circuit in its two-dimensional projection (a plane), thus allowing the use of photographic processing concepts such as film negatives to mask the projection of light exposed chemicals. This allows the use of a series of exposures on a substrate (silicon) to create silicon oxide (insulators) or doped regions (conductors). Together with the use of metallization, and the concepts of p–n junction isolation and surface passivation, it is possible to create circuits on a single silicon crystal slice (a wafer) from a monocrystalline silicon boule.

Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.

Silicon oxide may refer to either of the following:

p–n junction isolation is a method used to electrically isolate electronic components, such as transistors, on an integrated circuit (IC) by surrounding the components with reverse biased p–n junctions.

The process involves the basic procedures of silicon dioxide (SiO2) oxidation, SiO2 etching and heat diffusion. The final steps involves oxidizing the entire wafer with an SiO2 layer, etching contact vias to the transistors, and depositing a covering metal layer over the oxide, thus connecting the transistors without manually wiring them together.

Silicon dioxide chemical compound

Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as synthetic product. Notable examples include fused quartz, fumed silica, silica gel, and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries.

Thermal oxidation process creating a thin layer of silicon dioxide

In microfabrication, thermal oxidation is a way to produce a thin layer of oxide on the surface of a wafer. The technique forces an oxidizing agent to diffuse into the wafer at high temperature and react with it. The rate of oxide growth is often predicted by the Deal–Grove model. Thermal oxidation may be applied to different materials, but most commonly involves the oxidation of silicon substrates to produce silicon dioxide.

Oxide chemical compound with at least one oxygen atom

An oxide is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– atom. Metal oxides thus typically contain an anion of oxygen in the oxidation state of −2. Most of the Earth's crust consists of solid oxides, the result of elements being oxidized by the oxygen in air or in water. Hydrocarbon combustion affords the two principal carbon oxides: carbon monoxide and carbon dioxide. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 (called a passivation layer) that protects the foil from further corrosion. Individual elements can often form multiple oxides, each containing different amounts of the element and oxygen. In some cases these are distinguished by specifying the number of atoms as in carbon monoxide and carbon dioxide, and in other cases by specifying the element's oxidation number, as in iron(II) oxide and iron(III) oxide. Certain elements can form many different oxides, such as those of nitrogen. other examples are silicon, iron, titanium, and aluminium oxides.

History

Background

In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide could be grown on silicon. [1] Later in 1958, they proposed that silicon oxide layers could protect silicon surfaces during diffusion processes, and could be used for diffusion masking. [2] [3]

Carl John Frosch was a Bell Labs researcher who discovered that silicon could be protectively coated with silicon dioxide by the right exposure to oxygen when hot. Such protective coating overcame a problem of surface states found in active silicon circuit elements. The discovery also revealed the potential for the process of silicon etching.

Surface passivation, the process by which a semiconductor surface is rendered inert, and does not change semiconductor properties as a result of interaction with air or other materials in contact with the surface or edge of the crystal, [4] was first developed by Mohamed Atalla at BTL in the late 1950s. [5] [6] He discovered that the formation of a thermally grown silicon dioxide (SiO2) layer greatly reduced the concentration of electronic states at the silicon surface, [6] and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment. [3] He found that silicon oxide layers could be used to electrically stabilize silicon surfaces. [2] He developed the surface passivation process, a new method of semiconductor device fabrication that involves coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below. By growing a layer of silicon dioxide on top of a silicon wafer, Atalla was able to overcome the surface states that prevented electricity from reaching the semiconducting layer. [5] [7]

Surface states are electronic states found at the surface of materials. They are formed due to the sharp transition from solid material that ends with a surface and are found only at the atom layers closest to the surface. The termination of a material with a surface leads to a change of the electronic band structure from the bulk material to the vacuum. In the weakened potential at the surface, new electronic states can be formed, so called surface states.

A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films is a fundamental step in many applications. A familiar example is the household mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface. The process of silvering was once commonly used to produce mirrors, while more recently the metal layer is deposited using techniques such as sputtering. Advances in thin film deposition techniques during the 20th century have enabled a wide range of technological breakthroughs in areas such as magnetic recording media, electronic semiconductor devices, LEDs, optical coatings, hard coatings on cutting tools, and for both energy generation and storage. It is also being applied to pharmaceuticals, via thin-film drug delivery. A stack of thin films is called a multilayer.

Semiconductor device fabrication manufacturing process used to create integrated circuits

Semiconductor device fabrication is the process used to manufacture semiconductor devices, particularly the metal-oxide-semiconductor (MOS) devices used in the integrated circuit (IC) chips that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photolithographic and chemical processing steps during which electronic circuits are gradually created on a wafer made of pure semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications.

Atalla first published his findings in 1957. [8] [9] According to Fairchild Semiconductor engineer Chih-Tang Sah, the surface passivation process developed by Atalla and his team was "the most important and significant technology advance, which blazed the trail" that led to the silicon integrated circuit. [10] [11] [12]

Development

At a 1958 Electrochemical Society meeting, Mohamed Atalla presented a paper about the surface passivation of PN junctions by thermal oxidation, based on his 1957 BTL memos, [13] and demonstrated silicon dioxide's passivating effect on a silicon surface. [9] This was the first demonstration to show that high-quality silicon dioxide insulator films could be grown thermally on the silicon surface to protect the underlying silicon p-n junction diodes and transistors. [3]

Jean Hoerni attended the same 1958 meeting, and was intrigued by Atalla's presentation. Hoerni came up with the "planar idea" one morning while thinking about Atalla's device. [13] Taking advantage of silicon dioxide's passivating effect on the silicon surface, Hoerni proposed to make transistors that were protected by a layer of silicon dioxide. [13]

The planar process was developed by Jean Hoerni, one of the "traitorous eight", while working at Fairchild Semiconductor, with a first patent issued 1959. [14] [15]

Together with the use of metallization (to join together the integrated circuits), and the concept of p–n junction isolation (from Kurt Lehovec), the researchers at Fairchild were able to create circuits on a single silicon crystal slice (a wafer) from a monocrystalline silicon boule.

In 1959, Robert Noyce built on Hoerni's work with his conception of an integrated circuit (IC), which added a layer of metal to the top of Hoerni's basic structure to connect different components, such as transistors, capacitors, or resistors, located on the same piece of silicon. The planar process provided a powerful way of implementing an integrated circuit that was superior to earlier conceptions of the integrated circuit. [9] Noyce's invention was the first monolithic IC chip. [16] [17]

Early versions of the planar process used a photolithography process using near-ultraviolet light from a mercury vapor lamp. As of 2011, small features are typically made with 193 nm "deep" UV lithography. [18] Some researchers use even higher-energy extreme ultraviolet lithography.

See also

Related Research Articles

Integrated circuit electronic circuit manufactured by lithography; set of electronic circuits on one small flat piece (or "chip") of semiconductor material, normally silicon

An integrated circuit or monolithic integrated circuit is a set of electronic circuits on one small flat piece of semiconductor material that is normally silicon. The integration of large numbers of tiny MOS transistors into a small chip results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components. The IC's mass production capability, reliability, and building-block approach to circuit design has ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics. Computers, mobile phones, and other digital home appliances are now inextricable parts of the structure of modern societies, made possible by the small size and low cost of ICs.

Microelectromechanical systems technology of very small devices

Microelectromechanical systems is the technology of microscopic devices, particularly those with moving parts. It merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines in Japan, or micro systems technology (MST) in Europe.

Robert Noyce American businessman and engineer

Robert Norton Noyce, nicknamed "the Mayor of Silicon Valley," was an American physicist who co-founded Fairchild Semiconductor in 1957 and Intel Corporation in 1968. He is also credited with the realization of the first monolithic integrated circuit or microchip, which fueled the personal computer revolution and gave Silicon Valley its name.

MOSFET Transistor used for amplifying or switching electronic signals.

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 field-effect transistor that is fabricated by the controlled oxidation of a semiconductor, typically silicon. It has an insulated gate, whose voltage determines the 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 is the basic building block of modern electronics. Since its invention by Mohamed M. Atalla and Dawon Kahng at Bell Labs in November 1959, the MOSFET has become the most widely manufactured device in history, with an estimated total of 13 sextillion (1.3 × 1022) MOS transistors manufactured between 1960 and 2018.

Passivation, in physical chemistry and engineering, refers to a material becoming "passive," that is, less affected or corroded by the environment of future use. Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build from spontaneous oxidation in the air. As a technique, passivation is the use of a light coat of a protective material, such as metal oxide, to create a shell against corrosion. Passivation can occur only in certain conditions, and is used in microelectronics to enhance silicon. The technique of passivation strengthens and preserves the appearance of metallics. In electrochemical treatment of water, passivation reduces the effectiveness of the treatment by increasing the circuit resistance, and active measures are typically used to overcome this effect, the most common being polarity reversal, which results in limited rejection of the fouling layer. Other proprietary systems to avoid electrode passivation, several discussed below, are the subject of ongoing research and development.

Traitorous eight Group of PHDs employed at Shockley Semiconductor that left to form Fairchild Semiconductor.

The traitorous eight was a group of eight employees who left Shockley Semiconductor Laboratory in 1957 to found Fairchild Semiconductor. William Shockley had in 1956 recruited a group of young PhD graduates with the goal to develop and produce new semiconductor devices. While Shockley had received a Nobel Prize in Physics and was an experienced researcher and teacher, his management of the group was authoritarian and unpopular. This was accentuated by Shockley's research focus not proving fruitful. After the demand for Shockley to be replaced was rebuffed, the eight left to form their own company.

In electronics, a self-aligned gate is a transistor manufacturing feature whereby a refractory gate electrode region of a MOSFET is used as a mask for the doping of the source and drain regions. This technique ensures that the gate will slightly overlap the edges of the source and drain.

A diffused junction transistor is a transistor formed by diffusing dopants into a semiconductor substrate. The diffusion process was developed later than the alloy junction and grown junction processes for making BJTs.

A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. The vacuum-tube triode, also called a (thermionic) valve, was the transistor's precursor, introduced in 1907. The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925.

Chih-Tang "Tom" Sah is a Chinese-American engineer. He is best known for inventing CMOS logic with Frank Wanlass at Fairchild Semiconductor in 1963. CMOS is now used in nearly all modern very large-scale integration (VLSI) semiconductor devices.

The integrated circuit (IC) chip was invented during 1958–1959. The idea of integrating electronic circuits into a single device was born when the German physicist and engineer Werner Jacobi developed and patented the first known integrated transistor amplifier in 1949 and the British radio engineer Geoffrey Dummer proposed to integrate a variety of standard electronic components in a monolithic semiconductor crystal in 1952. A year later, Harwick Johnson filed a patent for a prototype IC. Between 1953 and 1957, Sidney Darlington and Yasuro Tarui proposed similar chip designs where several transistors could share a common active area, but there was no electrical isolation to separate them from each other.

Mohamed M. Atalla mechanical engineer

Mohamed M. Atalla was an Egyptian-American engineer, physical chemist, cryptographer, inventor, and entrepreneur. His pioneering work in semiconductor technology laid the foundations for modern electronics. Most importantly, his invention of the MOSFET in 1959, along with his earlier surface passivation and thermal oxidation processes, revolutionized the electronics industry. He is also known as the founder of the data security company Atalla Corporation, which he founded after he invented the first hardware security module (HSM) in 1972. He received the Stuart Ballantine Medal and was inducted into the National Inventors Hall of Fame for his important contributions to semiconductor technology as well as data security.

Bernard A Yurash was a significant contributor to the creation of the first commercially viable CMOS integrated circuits by finding the sources of mobile sodium ions coming from the manufacturing process. Today, virtually all digital electronics use CMOS circuitry. Bernard worked at Fairchild Semiconductor in Silicon Valley from 1958, through the buyouts of the company by Schlumberger and National Semiconductor, and finally retiring in 1990. In the 1960s Fairchild Semiconductor, a division of Fairchild Camera and Instrument Corp., and Texas Instruments, revolutionized electronics by employing the first integrated circuit technology. Fairchild's Robert Noyce filed for this patent using deposited (printed) metal lines and Jean Hoerni's Planar Process. At the time virtually all the devices were of the bipolar type which were used to construct RTL and DTL type circuits, which unfortunately drew more power than was desired, and eventually lost ground to Texas Instruments' TTL (Transistor-Transistor-logic). The next great technological leap in computer chips would be CMOS transistors, which promised significantly lower power and greater circuit density than the Bipolar circuitry. Although Frank Wanlass first filed for the CMOS patent in 1963, Fairchild could not produce the devices for commercial output for many years because of the mystery of the mobile ions degrading their performance. Much research time and money was expended in 1967 and 1968 at Fairchild on trying to manufacture the highly promising technology, the MOS SGT circuits utilizing the field effect from the "gate" on the conducting "channel" from source to drain.

References

  1. Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. pp. 22–23. ISBN   9780801886393.
  2. 1 2 Lécuyer, Christophe; Brock, David C. (2010). Makers of the Microchip: A Documentary History of Fairchild Semiconductor. MIT Press. p. 111. ISBN   9780262294324.
  3. 1 2 3 Saxena, A (2009). Invention of integrated circuits: untold important facts. International series on advances in solid state electronics and technology. World Scientific. pp. 96–97. ISBN   9789812814456.
  4. "Surface Passivation - an overview". ScienceDirect . Retrieved 19 August 2019.
  5. 1 2 "Martin Atalla in Inventors Hall of Fame, 2009" . Retrieved 21 June 2013.
  6. 1 2 Black, Lachlan E. (2016). New Perspectives on Surface Passivation: Understanding the Si-Al2O3 Interface. Springer. p. 17. ISBN   9783319325217.
  7. "Dawon Kahng". National Inventors Hall of Fame . Retrieved 27 June 2019.
  8. Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 120 & 321-323. ISBN   9783540342588.
  9. 1 2 3 Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. p. 46. ISBN   9780801886393.
  10. Wolf, Stanley (March 1992). "A review of IC isolation technologies". Solid State Technology: 63.
  11. Huff, Howard R.; Tsuya, H.; Gösele, U. (1998). Silicon Materials Science and Technology: Proceedings of the Eighth International Symposium on Silicon Materials Science and Technology. Electrochemical Society. pp. 181–182.
  12. Sah, Chih-Tang (October 1988). "Evolution of the MOS transistor-from conception to VLSI" (PDF). Proceedings of the IEEE . 76 (10): 1280–1326 (1290). doi:10.1109/5.16328. ISSN   0018-9219.
  13. 1 2 3 Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. p. 120. ISBN   9783540342588.
  14. US 3025589 Hoerni, J. A.: "Method of Manufacturing Semiconductor Devices” filed May 1, 1959
  15. US 3064167 Hoerni, J. A.: "Semiconductor device" filed May 15, 1960
  16. "1959: Practical Monolithic Integrated Circuit Concept Patented". Computer History Museum . Retrieved 13 August 2019.
  17. "Integrated circuits". NASA . Retrieved 13 August 2019.
  18. Shannon Hill. "UV Lithography: Taking Extreme Measures". National Institute of Standards and Technology (NIST).