Electronics. Mechanical watches. Semiconductor device fabrication. History When feature widths were far greater than about 10 micrometres, purity was not the issue that it is today in device manufacturing.
As devices became more integrated, cleanrooms became even cleaner. Today, the fabs are pressurized with filtered air to remove even the smallest particles, which could come to rest on the wafers and contribute to defects. The workers in a semiconductor fabrication facility are required to wear cleanroom suits to protect the devices from human contamination. Progress of miniaturisation, and comparison of sizes of semiconductor manufacturing process nodes with some microscopic objects and visible light wavelengths. Semiconductor device manufacturing has spread from Texas and California in the 1960s to the rest of the world, including Europe, the Middle East, and Asia.
Wafers Processing Modern chips have up to eleven metal levels produced in over 300 sequenced processing steps. Amorphous silicon. Amorphous silicon (a-Si) is the non-crystalline form of silicon used for solar cells and thin-film transistors in LCD displays.
Used as semiconductor material for a-Si solar cells, or thin-film silicon solar cells, it is deposited in thin films onto a variety of flexible substrates, such as glass, metal and plastic. Amorphous silicon cells generally feature low efficiency, but are one of the most environmentally friendly photovoltaic technologies, since they do not use any toxic heavy metals such as cadmium or lead. As a second-generation thin-film solar cell technology, amorphous silicon was once expected to become a major contributor in the fast-growing worldwide photovoltaic market, but has since lost its significance due to strong competition from conventional crystalline silicon cells and other thin-film technologies such as CdTe and CIGS.
Description Silicon is a fourfold coordinated atom that is normally tetrahedrally bonded to four neighboring silicon atoms. Black silicon. Properties Scanning electron micrograph of black silicon, produced by RIE (ASE process) SEM micrograph of black silicon formed by cryogenic RIE.
Notice the smooth, sloped surfaces, unlike the undulated sidewalls obtained with the Bosch process RIE. Black silicon is a needle-shaped surface structure where needles are made of single-crystal silicon and have a height above 10 µm and diameter less than 1 µm. Its main feature is an increased absorption of incident light—the high reflectivity of the silicon, which is usually 20–30% for quasi-normal incidence, is reduced to about 5%. This is due to the formation of a so-called effective medium by the needles. Applications The unusual optical characteristics, combined with the semiconducting properties of silicon make this material interesting for sensor applications.
Covalent superconductor. Covalent superconductors are superconducting materials where the atoms are linked by covalent bonds.
The first such material was synthetic diamond grown by the high-pressure high-temperature (HPHT) method. The discovery had no practical importance, but surprised most scientists as superconductivity had not been observed in covalent semiconductors, including diamond and silicon. Diamond Superconductivity in diamond was achieved through heavy p-type doping by boron such that the individual doping atoms started interacting and formed an "impurity band". The superconductivity was of type-II with the critical temperature Tc = 4 K and critical magnetic field Hc = 4 T. Later, Tc ~ 11K has been achieved in homoepitaxial CVD films. Silicon Silicon carbide Superconductivity in SiC was achieved by heavy doping with boron or aluminum. Both the cubic (3C-SiC) and hexagonal (6H-SiC) phases are superconducting and show a very similar Tc of 1.5 K. Transistor. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.
It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes 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. The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Printed electronics. Gravure printing of electronic structures on paper.
Printed electronics is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. By electronic industry standards, these are low cost processes. Electrically functional electronic or optical inks are deposited on the substrate, creating active or passive devices, such as thin film transistors or resistors. Printed electronics is expected to facilitate widespread, very low-cost, low-performance electronics for applications such as flexible displays, smart labels, decorative and animated posters, and active clothing that do not require high performance. The term printed electronics is often related to organic electronics or plastic electronics, in which one or more inks are composed of carbon-based compounds.