p–n junction isolation is a method used to electrically isolate

electronic component An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are n ...

s, such as

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...

s, on an integrated circuit (IC) by surrounding the components with

reverse bias Reverse or reversing may refer to: Arts and media * ''Reverse'' (Eldritch album), 2001 * ''Reverse'' (2009 film), a Polish comedy-drama film * ''Reverse'' (2019 film), an Iranian crime-drama film * ''Reverse'' (Morandi album), 2005 * ''Reverse'' ...

p–n junction A p–n junction is a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. The "p" (positive) side contains an excess of holes, while the "n" (negative) side contai ...

Introduction

By surrounding a transistor, resistor, capacitor or other component on an IC with semiconductor material which is doped using an opposite species of the substrate

dopant A dopant, also called a doping agent, is a trace of impurity element that is introduced into a chemical material to alter its original electrical or optical properties. The amount of dopant necessary to cause changes is typically very low. Wh ...

, and connecting this surrounding material to a voltage which reverse-biases the

that forms, it is possible to create a region which forms an electrically isolated "well" around the component.

Operation

Assume that the

semiconductor wafer In electronics, a wafer (also called a slice or substrate) is a thin slice of semiconductor, such as a crystalline silicon (c-Si), used for the fabrication of integrated circuits and, in photovoltaics, to manufacture solar cells. The wafer ser ...

is p-type material. Also assume a ring of n-type material is placed around a transistor, and placed beneath the transistor. If the p-type material within the n-type ring is now connected to the

negative terminal A terminal is the point at which a conductor from a component, device or network comes to an end. ''Terminal'' may also refer to an electrical connector at this endpoint, acting as the reusable interface to a conductor and creating a point whe ...

of the power supply and the n-type ring is connected to the

positive terminal A terminal is the point at which a conductor from a component, device or network comes to an end. ''Terminal'' may also refer to an electrical connector at this endpoint, acting as the reusable interface to a conductor and creating a point whe ...

, the ' holes' in the p-type region are pulled away from the p–n junction, causing the width of the

nonconducting An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and electrical conductor, conductors—con ...

depletion region In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile ...

to increase. Similarly, because the n-type region is connected to the positive terminal, the electrons will also be pulled away from the junction. This effectively increases the

potential barrier In quantum mechanics, the rectangular (or, at times, square) potential barrier is a standard one-dimensional problem that demonstrates the phenomena of wave-mechanical tunneling (also called "quantum tunneling") and wave-mechanical reflection. T ...

and greatly increases the

electrical resistance The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallel ...

against the flow of

charge carrier In physics, a charge carrier is a particle or quasiparticle that is free to move, carrying an electric charge, especially the particles that carry electric charges in electrical conductors. Examples are electrons, ions and holes. The term is u ...

s. For this reason there will be no (or minimal)

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movin ...

across the junction. At the middle of the junction of the p–n material, a

is created to stand-off the reverse voltage. The width of the

grows larger with higher voltage. The electric field grows as the reverse voltage increases. When the electric field increases beyond a critical level, the junction breaks down and current begins to flow by

avalanche breakdown Avalanche breakdown (or avalanche effect) is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good ...

. Therefore, care must be taken that circuit voltages do not exceed the breakdown voltage or electrical isolation ceases.

History

In an article entitled "Microelectronics", published in ''

Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it i ...

'', September 1977 Volume 23, Number 3, pp. 63–9, Robert Noyce wrote:

"The integrated circuit, as we conceived and developed it at Fairchild Semiconductor in 1959, accomplishes the separation and interconnection of transistors and other circuit elements electrically rather than physically. The separation is accomplished by introducing pn diodes, or rectifiers, which allow current to flow in only one direction. The technique was patented by Kurt Lehovec at the Sprague Electric Company".

Sprague Electric Company engineer

Kurt Lehovec Kurt Lehovec (June 12, 1918 – February 17, 2012) was one of the pioneers of the integrated circuit. While also pioneering the photo-voltaic effect, light-emitting diodes and lithium batteries, he innovated the concept of p-n junction isol ...

filed for p–n junction isolation in 1959, and was granted the patent in 1962. He is reported (during his lectures on semiconductor memory cells) to have said "I never got a dime out of it

he patent He or HE may refer to: Language * He (pronoun), an English pronoun * He (kana), the romanization of the Japanese kana へ * He (letter), the fifth letter of many Semitic alphabets * He (Cyrillic), a letter of the Cyrillic script called ''He'' in ...

" However, I T Histor
states
he was paid (''pro forma'') at least one dollar for what is possibly the most important invention in history, as it also was instrumental in the invention of the

LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

and the

solar cell A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.Lau Wai Shing says Lehovec als
pioneered
the research of. When

Robert Noyce Robert Norton Noyce (December 12, 1927 – June 3, 1990), nicknamed "the Mayor of Silicon Valley", was an American physicist and entrepreneur who co-founded Fairchild Semiconductor in 1957 and Intel Corporation in 1968. He is also credited wit ...

invented the

monolithic integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...

in 1959, his idea of p–n junction isolation was based on Hoerni's planar process. In 1976, Noyce stated that, in January 1959, he did not know about the work of Lehovec.

References

{{DEFAULTSORT:P-n junction isolation Semiconductor structures Integrated circuits Czech inventions

Introduction

Operation

History

See also

References