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126-511: The telescope was completed in the year 2000 for an exoplanet research program. The telescope contains two different measuring devices. First of all, there is the MeropeII CCD camera . This camera has a size of 2k by 6k pixels Frame Transfer detector originally designed for ESA's canceled Eddington space mission. The filters used together with this camera are according to the so-called geneva photometric system . The second instrument on

252-534: A MOSFET (metal–oxide–semiconductor field-effect transistor) using the silicon-on-sapphire process at RCA Laboratories . Semiconductor device manufacturing has since spread from Texas and California in the 1960s to the rest of the world, including Asia , Europe , and the Middle East . Wafer size has grown over time, from 25 mm in 1960, to 50 mm in 1969, 100 mm in 1976, 125 mm in 1981, 150 mm in 1983 and 200 mm in 1992. In

378-423: A charge amplifier , which converts the charge into a voltage . By repeating this process, the controlling circuit converts the entire contents of the array in the semiconductor to a sequence of voltages. In a digital device, these voltages are then sampled, digitized, and usually stored in memory; in an analog device (such as an analog video camera), they are processed into a continuous analog signal (e.g. by feeding

504-481: A shift register . The essence of the design was the ability to transfer charge along the surface of a semiconductor from one storage capacitor to the next. The concept was similar in principle to the bucket-brigade device (BBD), which was developed at Philips Research Labs during the late 1960s. The first experimental device demonstrating the principle was a row of closely spaced metal squares on an oxidized silicon surface electrically accessed by wire bonds. It

630-485: A CCD is the higher cost: the cell area is basically doubled, and more complex control electronics are needed. An intensified charge-coupled device (ICCD) is a CCD that is optically connected to an image intensifier that is mounted in front of the CCD. An image intensifier includes three functional elements: a photocathode , a micro-channel plate (MCP) and a phosphor screen. These three elements are mounted one close behind

756-669: A cooling system—using either thermoelectric cooling or liquid nitrogen—to cool the chip down to temperatures in the range of −65 to −95 °C (−85 to −139 °F). This cooling system adds additional costs to the EMCCD imaging system and may yield condensation problems in the application. However, high-end EMCCD cameras are equipped with a permanent hermetic vacuum system confining the chip to avoid condensation issues. The low-light capabilities of EMCCDs find use in astronomy and biomedical research, among other fields. In particular, their low noise at high readout speeds makes them very useful for

882-428: A factor of 2–3 compared to the surface-channel CCD. The gate oxide, i.e. the capacitor dielectric , is grown on top of the epitaxial layer and substrate. Later in the process, polysilicon gates are deposited by chemical vapor deposition , patterned with photolithography , and etched in such a way that the separately phased gates lie perpendicular to the channels. The channels are further defined by utilization of

1008-555: A few percent. That image can then be read out slowly from the storage region while a new image is integrating or exposing in the active area. Frame-transfer devices typically do not require a mechanical shutter and were a common architecture for early solid-state broadcast cameras. The downside to the frame-transfer architecture is that it requires twice the silicon real estate of an equivalent full-frame device; hence, it costs roughly twice as much. The interline architecture extends this concept one step further and masks every other column of

1134-429: A full-frame device, all of the image area is active, and there is no electronic shutter. A mechanical shutter must be added to this type of sensor or the image smears as the device is clocked or read out. With a frame-transfer CCD, half of the silicon area is covered by an opaque mask (typically aluminum). The image can be quickly transferred from the image area to the opaque area or storage region with acceptable smear of

1260-592: A gain register is placed between the shift register and the output amplifier. The gain register is split up into a large number of stages. In each stage, the electrons are multiplied by impact ionization in a similar way to an avalanche diode . The gain probability at every stage of the register is small ( P < 2%), but as the number of elements is large (N > 500), the overall gain can be very high ( g = ( 1 + P ) N {\displaystyle g=(1+P)^{N}} ), with single input electrons giving many thousands of output electrons. Reading

1386-401: A large lateral electric field from one gate to the next. This provides an additional driving force to aid in transfer of the charge packets. The CCD image sensors can be implemented in several different architectures. The most common are full-frame, frame-transfer, and interline. The distinguishing characteristic of each of these architectures is their approach to the problem of shuttering. In

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1512-417: A layer of silicon dioxide over the silicon wafer, for which they observed surface passivation effects. By 1957 Frosch and Derick, using masking and predeposition, were able to manufacture silicon dioxide transistors; the first planar field effect transistors, in which drain and source were adjacent at the same surface. At Bell Labs, the importance of their discoveries was immediately realized. Memos describing

1638-399: A non-equilibrium state called deep depletion. Then, when electron–hole pairs are generated in the depletion region, they are separated by the electric field, the electrons move toward the surface, and the holes move toward the substrate. Four pair-generation processes can be identified: The last three processes are known as dark-current generation, and add noise to the image; they can limit

1764-417: A p+ doped region underlying them, providing a further barrier to the electrons in the charge packets (this discussion of the physics of CCD devices assumes an electron transfer device, though hole transfer is possible). The clocking of the gates, alternately high and low, will forward and reverse bias the diode that is provided by the buried channel (n-doped) and the epitaxial layer (p-doped). This will cause

1890-638: A rate of 4 Hz , changing between the filters of the photometric system. The Swiss Euler 1.2m Telescope and the Mercator Telescope were part of the Southern Sky extrasolar Planet search Programme which has discovered numerous extrasolar planets. The Hermes spectrograph was used to monitor the Star Delta Cephei in the 2010s. The data seemed to suggest a previously unknown stellar companion. The Hermes spectrograph for Mercator

2016-409: A reflective material such as aluminium. When the exposure time is up, the cells are transferred very rapidly to the hidden area. Here, safe from any incoming light, cells can be read out at any speed one deems necessary to correctly measure the cells' charge. At the same time, the exposed part of the CCD is collecting light again, so no delay occurs between successive exposures. The disadvantage of such

2142-543: A semiconductor device might not need all techniques. Equipment for carrying out these processes is made by a handful of companies . All equipment needs to be tested before a semiconductor fabrication plant is started. These processes are done after integrated circuit design . A semiconductor fab operates 24/7 and many fabs use large amounts of water, primarily for rinsing the chips. Additionally steps such as Wright etch may be carried out. When feature widths were far greater than about 10 micrometres , semiconductor purity

2268-419: A semiconductor fabrication facility are required to wear cleanroom suits to protect the devices from contamination by humans. To increase yield, FOUPs and semiconductor capital equipment may have a mini environment with ISO class 1 level of dust, and FOUPs can have an even cleaner micro environment. FOUPs and SMIF pods isolate the wafers from the air in the cleanroom, increasing yield because they reduce

2394-445: A signal from a CCD gives a noise background, typically a few electrons. In an EMCCD, this noise is superimposed on many thousands of electrons rather than a single electron; the devices' primary advantage is thus their negligible readout noise. The use of avalanche breakdown for amplification of photo charges had already been described in the U.S. patent 3,761,744 in 1973 by George E. Smith/Bell Telephone Laboratories. EMCCDs show

2520-422: A similar sensitivity to intensified CCDs (ICCDs). However, as with ICCDs, the gain that is applied in the gain register is stochastic and the exact gain that has been applied to a pixel's charge is impossible to know. At high gains (> 30), this uncertainty has the same effect on the signal-to-noise ratio (SNR) as halving the quantum efficiency (QE) with respect to operation with a gain of unity. This effect

2646-432: A simple die shrink of a currently produced chip design to reduce costs, improve performance, and increase transistor density (number of transistors per unit area) without the expense of a new design. Early semiconductor processes had arbitrary names for generations (viz., HMOS I/II/III/IV and CHMOS III/III-E/IV/V). Later each new generation process became known as a technology node or process node , designated by

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2772-416: A single slice of the image, whereas a two-dimensional array, used in video and still cameras, captures a two-dimensional picture corresponding to the scene projected onto the focal plane of the sensor. Once the array has been exposed to the image, a control circuit causes each capacitor to transfer its contents to its neighbor (operating as a shift register). The last capacitor in the array dumps its charge into

2898-411: A small part of the device such as a memory cell to store data. Thus F is used to measure the area taken up by these cells or sections. A specific semiconductor process has specific rules on the minimum size (width or CD/Critical Dimension) and spacing for features on each layer of the chip. Normally a new semiconductor process has smaller minimum sizes and tighter spacing. In some cases, this allows

3024-424: A time. During the readout phase, cells are shifted down the entire area of the CCD. While they are shifted, they continue to collect light. Thus, if the shifting is not fast enough, errors can result from light that falls on a cell holding charge during the transfer. These errors are referred to as "vertical smear" and cause a strong light source to create a vertical line above and below its exact location. In addition,

3150-464: A variety of astronomical applications involving low light sources and transient events such as lucky imaging of faint stars, high speed photon counting photometry, Fabry-Pérot spectroscopy and high-resolution spectroscopy. More recently, these types of CCDs have broken into the field of biomedical research in low-light applications including small animal imaging , single-molecule imaging , Raman spectroscopy , super resolution microscopy as well as

3276-472: A wafer box or a wafer carrying box. In semiconductor device fabrication, the various processing steps fall into four general categories: deposition, removal, patterning, and modification of electrical properties. Modification of electrical properties now also extends to the reduction of a material's dielectric constant in low-κ insulators via exposure to ultraviolet light in UV processing (UVP). Modification

3402-408: A wafer will be processed by a particular machine in a processing step during manufacturing. Process variability is a challenge in semiconductor processing, in which wafers are not processed evenly or the quality or effectiveness of processes carried out on a wafer are not even across the wafer surface. Wafer processing is separated into FEOL and BEOL stages. FEOL processing refers to the formation of

3528-438: A wide variety of modern fluorescence microscopy techniques thanks to greater SNR in low-light conditions in comparison with traditional CCDs and ICCDs. Semiconductor device fabrication Semiconductor device fabrication is the process used to manufacture semiconductor devices , typically integrated circuits (ICs) such as computer processors , microcontrollers , and memory chips (such as RAM and Flash memory ). It

3654-429: Is a multiple-step photolithographic and physico-chemical process (with steps such as thermal oxidation , thin-film deposition, ion-implantation, etching) during which electronic circuits are gradually created on a wafer , typically made of pure single-crystal semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications. The fabrication process

3780-410: Is a photoactive region (an epitaxial layer of silicon), and a transmission region made out of a shift register (the CCD, properly speaking). An image is projected through a lens onto the capacitor array (the photoactive region), causing each capacitor to accumulate an electric charge proportional to the light intensity at that location. A one-dimensional array, used in line-scan cameras, captures

3906-432: Is a specialized CCD, often used in astronomy and some professional video cameras , designed for high exposure efficiency and correctness. The normal functioning of a CCD, astronomical or otherwise, can be divided into two phases: exposure and readout. During the first phase, the CCD passively collects incoming photons , storing electrons in its cells. After the exposure time is passed, the cells are read out one line at

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4032-402: Is an integrated circuit containing an array of linked, or coupled, capacitors . Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging . In a CCD image sensor , pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors . These MOS capacitors ,

4158-788: Is deposited. Once the epitaxial silicon is deposited, the crystal lattice becomes stretched somewhat, resulting in improved electronic mobility. Another method, called silicon on insulator technology involves the insertion of an insulating layer between the raw silicon wafer and the thin layer of subsequent silicon epitaxy. This method results in the creation of transistors with reduced parasitic effects . Semiconductor equipment may have several chambers which process wafers in processes such as deposition and etching. Many pieces of equipment handle wafers between these chambers in an internal nitrogen or vacuum environment to improve process control. Wet benches with tanks containing chemical solutions were historically used for cleaning and etching wafers. At

4284-403: Is frequently achieved by oxidation , which can be carried out to create semiconductor-insulator junctions, such as in the local oxidation of silicon ( LOCOS ) to fabricate metal oxide field effect transistors . Modern chips have up to eleven or more metal levels produced in over 300 or more sequenced processing steps. A recipe in semiconductor manufacturing is a list of conditions under which

4410-403: Is known as the linewidth. Patterning often refers to photolithography which allows a device design or pattern to be defined on the device during fabrication. F is used as a measurement of area for different parts of a semiconductor device, based on the feature size of a semiconductor manufacturing process. Many semiconductor devices are designed in sections called cells, and each cell represents

4536-407: Is often based on tungsten and has upper and lower layers: the lower layer connects the junctions of the transistors, and an upper layer which is a tungsten plug that connects the transistors to the interconnect. Intel at the 10nm node introduced contact-over-active-gate (COAG) which, instead of placing the contact for connecting the transistor close to the gate of the transistor, places it directly over

4662-565: Is one of the major advantages of the ICCD over the EMCCD cameras. The highest performing ICCD cameras enable shutter times as short as 200 picoseconds . ICCD cameras are in general somewhat higher in price than EMCCD cameras because they need the expensive image intensifier. On the other hand, EMCCD cameras need a cooling system to cool the EMCCD chip down to temperatures around 170  K (−103  °C ). This cooling system adds additional costs to

4788-446: Is performed in highly specialized semiconductor fabrication plants , also called foundries or "fabs", with the central part being the " clean room ". In more advanced semiconductor devices, such as modern 14 / 10 / 7 nm nodes, fabrication can take up to 15 weeks, with 11–13 weeks being the industry average. Production in advanced fabrication facilities is completely automated, with automated material handling systems taking care of

4914-564: Is referred to as the Excess Noise Factor (ENF). However, at very low light levels (where the quantum efficiency is most important), it can be assumed that a pixel either contains an electron—or not. This removes the noise associated with the stochastic multiplication at the risk of counting multiple electrons in the same pixel as a single electron. To avoid multiple counts in one pixel due to coincident photons in this mode of operation, high frame rates are essential. The dispersion in

5040-512: Is the probability of getting n output electrons given m input electrons and a total mean multiplication register gain of g . For very large numbers of input electrons, this complex distribution function converges towards a Gaussian. Because of the lower costs and better resolution, EMCCDs are capable of replacing ICCDs in many applications. ICCDs still have the advantage that they can be gated very fast and thus are useful in applications like range-gated imaging . EMCCD cameras indispensably need

5166-422: Is the right choice. Consumer snap-shot cameras have used interline devices. On the other hand, for those applications that require the best possible light collection and issues of money, power and time are less important, the full-frame device is the right choice. Astronomers tend to prefer full-frame devices. The frame-transfer falls in between and was a common choice before the fill-factor issue of interline devices

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5292-405: Is used in the construction of interline-transfer devices. Another version of CCD is called a peristaltic CCD. In a peristaltic charge-coupled device, the charge-packet transfer operation is analogous to the peristaltic contraction and dilation of the digestive system . The peristaltic CCD has an additional implant that keeps the charge away from the silicon/ silicon dioxide interface and generates

5418-586: The Czochralski process . These ingots are then sliced into wafers about 0.75 mm thick and polished to obtain a very regular and flat surface. During the production process wafers are often grouped into lots, which are represented by a FOUP, SMIF or a wafer cassette, which are wafer carriers. FOUPs and SMIFs can be transported in the fab between machines and equipment with an automated OHT (Overhead Hoist Transport) AMHS (Automated Material Handling System). Besides SMIFs and FOUPs, wafer cassettes can be placed in

5544-514: The High-κ dielectric , creating dummy gates, manufacturing sources and drains by ion deposition and dopant annealing, depositing an "interlevel dielectric (ILD)" and then polishing, and removing the dummy gates to replace them with a metal whose workfunction depended on whether the transistor was NMOS or PMOS, thus creating the metal gate. A third process, full silicidation (FUSI) was not pursued due to manufacturing problems. Gate-first became dominant at

5670-681: The Kodak Apparatus Division, invented a digital still camera using this same Fairchild 100 × 100 CCD in 1975. The interline transfer (ILT) CCD device was proposed by L. Walsh and R. Dyck at Fairchild in 1973 to reduce smear and eliminate a mechanical shutter . To further reduce smear from bright light sources, the frame-interline-transfer (FIT) CCD architecture was developed by K. Horii, T. Kuroda and T. Kunii at Matsushita (now Panasonic) in 1981. The first KH-11 KENNEN reconnaissance satellite equipped with charge-coupled device array ( 800 × 800 pixels) technology for imaging

5796-566: The LOCOS process to produce the channel stop region. Channel stops are thermally grown oxides that serve to isolate the charge packets in one column from those in another. These channel stops are produced before the polysilicon gates are, as the LOCOS process utilizes a high-temperature step that would destroy the gate material. The channel stops are parallel to, and exclusive of, the channel, or "charge carrying", regions. Channel stops often have

5922-473: The photodiode to the CCD. This led to their invention of the pinned photodiode, a photodetector structure with low lag, low noise , high quantum efficiency and low dark current . It was first publicly reported by Teranishi and Ishihara with A. Kohono, E. Oda and K. Arai in 1982, with the addition of an anti-blooming structure. The new photodetector structure invented at NEC was given the name "pinned photodiode" (PPD) by B.C. Burkey at Kodak in 1984. In 1987,

6048-429: The transistors directly in the silicon . The raw wafer is engineered by the growth of an ultrapure, virtually defect-free silicon layer through epitaxy . In the most advanced logic devices , prior to the silicon epitaxy step, tricks are performed to improve the performance of the transistors to be built. One method involves introducing a straining step wherein a silicon variant such as silicon-germanium (SiGe)

6174-437: The 1970s. High-k dielectric such as hafnium oxide (HfO 2 ) replaced silicon oxynitride (SiON), in order to prevent large amounts of leakage current in the transistor while allowing for continued scaling or shrinking of the transistors. However HfO 2 is not compatible with polysilicon gates which requires the use of a metal gate. Two approaches were used in production: gate-first and gate-last. Gate-first consists of depositing

6300-414: The 22nm node, because planar transistors which only have one surface acting as a channel, started to suffer from short channel effects. A startup called SuVolta created a technology called Deeply Depleted Channel (DDC) to compete with FinFET transistors, which uses planar transistors at the 65 nm node which are very lightly doped. By 2018, a number of transistor architectures had been proposed for

6426-601: The 22nm/20nm node. HKMG has been extended from planar transistors for use in FinFET and nanosheet transistors. Hafnium silicon oxynitride can also be used instead of Hafnium oxide. Since the 16nm/14nm node, Atomic layer etching (ALE) is increasingly used for etching as it offers higher precision than other etching methods. In production, plasma ALE is commonly used, which removes materials unidirectionally, creating structures with vertical walls. Thermal ALE can also be used to remove materials isotropically, in all directions at

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6552-463: The 350nm and 250nm nodes (0.35 and 0.25 micron nodes), at the same time chemical mechanical polishing began to be employed. At the time, 2 metal layers for interconnect, also called metallization was state-of-the-art. Since the 22nm node, some manufacturers have added a new process called middle-of-line (MOL) which connects the transistors to the rest of the interconnect made in the BEoL process. The MOL

6678-537: The 90nm node, transistor channels made with strain engineering were introduced to improve drive current in PMOS transistors by introducing regions with Silicon-Germanium in the transistor. The same was done in NMOS transistors at the 20nm node. In 2007, HKMG (high-k/metal gate) transistors were introduced by Intel at the 45nm node, which replaced polysilicon gates which in turn replaced metal gate (aluminum gate) technology in

6804-399: The CCD cannot be used to collect light while it is being read out. A faster shifting requires a faster readout, and a faster readout can introduce errors in the cell charge measurement, leading to a higher noise level. A frame transfer CCD solves both problems: it has a shielded, not light sensitive, area containing as many cells as the area exposed to light. Typically, this area is covered by

6930-402: The CCD concept. Michael Tompsett was awarded the 2010 National Medal of Technology and Innovation , for pioneering work and electronic technologies including the design and development of the first CCD imagers. He was also awarded the 2012 IEEE Edison Medal for "pioneering contributions to imaging devices including CCD Imagers, cameras and thermal imagers". In a CCD for capturing images, there

7056-545: The CCD to deplete, near the p–n junction and will collect and move the charge packets beneath the gates—and within the channels—of the device. CCD manufacturing and operation can be optimized for different uses. The above process describes a frame transfer CCD. While CCDs may be manufactured on a heavily doped p++ wafer it is also possible to manufacture a device inside p-wells that have been placed on an n-wafer. This second method, reportedly, reduces smear, dark current , and infrared and red response. This method of manufacture

7182-477: The CCD-G5, was released by Sony in 1983, based on a prototype developed by Yoshiaki Hagiwara in 1981. Early CCD sensors suffered from shutter lag . This was largely resolved with the invention of the pinned photodiode (PPD). It was invented by Nobukazu Teranishi , Hiromitsu Shiraki and Yasuo Ishihara at NEC in 1980. They recognized that lag can be eliminated if the signal carriers could be transferred from

7308-511: The EFEM which helps reduce the amount of humidity that enters the FOUP and improves yield. Companies that manufacture machines used in the industrial semiconductor fabrication process include ASML , Applied Materials , Tokyo Electron and Lam Research . Feature size is determined by the width of the smallest lines that can be patterned in a semiconductor fabrication process, this measurement

7434-404: The EMCCD camera and often yields heavy condensation problems in the application. ICCDs are used in night vision devices and in various scientific applications. An electron-multiplying CCD (EMCCD, also known as an L3Vision CCD, a product commercialized by e2v Ltd., GB, L3CCD or Impactron CCD, a now-discontinued product offered in the past by Texas Instruments) is a charge-coupled device in which

7560-453: The FOUPs into the machine. Additionally many machines also handle wafers in clean nitrogen or vacuum environments to reduce contamination and improve process control. Fabrication plants need large amounts of liquid nitrogen to maintain the atmosphere inside production machinery and FOUPs, which are constantly purged with nitrogen. There can also be an air curtain or a mesh between the FOUP and

7686-463: The Mercator Telescope is the HERMES echelle spectrograph . It covers a wavelength range between 380 and 875 nm with a spectral resolution of R~85000. The P7 photometer was active from May 2001 until July 2008. The photometer measured in the 7 band Geneva photometric system. It measured the star in one channel and the sky in another so that the sky can be subtracted. The filter wheel is turning at

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7812-610: The PPD began to be incorporated into most CCD devices, becoming a fixture in consumer electronic video cameras and then digital still cameras . Since then, the PPD has been used in nearly all CCD sensors and then CMOS sensors . In January 2006, Boyle and Smith were awarded the National Academy of Engineering Charles Stark Draper Prize , and in 2009 they were awarded the Nobel Prize for Physics for their invention of

7938-497: The Precision 5000. Until the 1980s, physical vapor deposition was the primary technique used for depositing materials onto wafers, until the advent of chemical vapor deposition. Equipment with diffusion pumps was replaced with those using turbomolecular pumps as the latter do not use oil which often contaminated wafers during processing in vacuum. 200 mm diameter wafers were first used in 1990 for making chips. These became

8064-511: The Producer, a cluster tool that had chambers grouped in pairs for processing wafers, which shared common vacuum and supply lines but were otherwise isolated, which was revolutionary at the time as it offered higher productivity than other cluster tools without sacrificing quality, due to the isolated chamber design. The semiconductor industry is a global business today. The leading semiconductor manufacturers typically have facilities all over

8190-530: The adoption of FOUPs, but many products that are not advanced are still produced in 200 mm wafers such as analog ICs, RF chips, power ICs, BCDMOS and MEMS devices. Some processes such as cleaning, ion implantation, etching, annealing and oxidation started to adopt single wafer processing instead of batch wafer processing in order to improve the reproducibility of results. A similar trend existed in MEMS manufacturing. In 1998, Applied Materials introduced

8316-400: The air in the cleanroom; semiconductor capital equipment may also have their own FFUs to clean air in the equipment's EFEM which allows the equipment to receive wafers in FOUPs. The FFUs, combined with raised floors with grills, help ensure a laminar air flow, to ensure that particles are immediately brought down to the floor and do not stay suspended in the air due to turbulence. The workers in

8442-451: The array's dark current , improving the sensitivity of the CCD to low light intensities, even for ultraviolet and visible wavelengths. Professional observatories often cool their detectors with liquid nitrogen to reduce the dark current, and therefore the thermal noise , to negligible levels. The frame transfer CCD imager was the first imaging structure proposed for CCD Imaging by Michael Tompsett at Bell Laboratories. A frame transfer CCD

8568-544: The average utilization of semiconductor devices increased, durability became an issue and manufacturers started to design their devices to ensure they last for enough time, and this depends on the market the device is designed for. This especially became a problem at the 10 nm node. Silicon on insulator (SOI) technology has been used in AMD 's 130 nm, 90 nm, 65 nm, 45 nm and 32 nm single, dual, quad, six and eight core processors made since 2001. During

8694-692: The basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras , active pixel sensors , also known as CMOS sensors (complementary MOS sensors), are generally used. However,

8820-402: The basis of CMOS technology today. An improved type of MOSFET technology, CMOS , was developed by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. CMOS was commercialised by RCA in the late 1960s. RCA commercially used CMOS for its 4000-series integrated circuits in 1968, starting with a 20   μm process before gradually scaling to a 10 μm process over

8946-400: The carrier, processed and returned to the carrier, so acid-resistant carriers were developed to eliminate this time consuming process, so the entire cassette with wafers was dipped into wet etching and wet cleaning tanks. When wafer sizes increased to 100 mm, the entire cassette would often not be dipped as uniformly, and the quality of the results across the wafer became hard to control. By

9072-426: The channel in which the photogenerated charge packets will travel. Simon Sze details the advantages of a buried-channel device: This thin layer (= 0.2–0.3 micron) is fully depleted and the accumulated photogenerated charge is kept away from the surface. This structure has the advantages of higher transfer efficiency and lower dark current, from reduced surface recombination. The penalty is smaller charge capacity, by

9198-451: The charge could be stepped along from one to the next. This led to the invention of the charge-coupled device by Boyle and Smith in 1969. They conceived of the design of what they termed, in their notebook, "Charge 'Bubble' Devices". The initial paper describing the concept in April 1970 listed possible uses as memory , a delay line, and an imaging device. The device could also be used as

9324-476: The company's financial abilities. From 2020 to 2022, there was a global chip shortage . During this shortage caused by the COVID-19 pandemic, many semiconductor manufacturers banned employees from leaving company grounds. Many countries granted subsidies to semiconductor companies for building new fabrication plants or fabs. Many companies were affected by counterfeit chips. Semiconductors have become vital to

9450-502: The depth of focus of available lithography, and thus interfering with the ability to pattern. CMP ( chemical-mechanical planarization ) is the primary processing method to achieve such planarization, although dry etch back is still sometimes employed when the number of interconnect levels is no more than three. Copper interconnects use an electrically conductive barrier layer to prevent the copper from diffusing into ("poisoning") its surroundings, often made of tantalum nitride. In 1997, IBM

9576-424: The desired complementary electrical properties. In dynamic random-access memory (DRAM) devices, storage capacitors are also fabricated at this time, typically stacked above the access transistor (the now defunct DRAM manufacturer Qimonda implemented these capacitors with trenches etched deep into the silicon surface). Once the various semiconductor devices have been created , they must be interconnected to form

9702-746: The desired electrical circuits. This occurs in a series of wafer processing steps collectively referred to as BEOL (not to be confused with back end of chip fabrication, which refers to the packaging and testing stages). BEOL processing involves creating metal interconnecting wires that are isolated by dielectric layers. The insulating material has traditionally been a form of SiO 2 or a silicate glass , but recently new low dielectric constant materials, also called low-κ dielectrics, are being used (such as silicon oxycarbide), typically providing dielectric constants around 2.7 (compared to 3.82 for SiO 2 ), although materials with constants as low as 2.2 are being offered to chipmakers. BEoL has been used since 1995 at

9828-411: The entire wafer is scrapped to avoid the costs of further processing. Virtual metrology has been used to predict wafer properties based on statistical methods without performing the physical measurement itself. Once the front-end process has been completed, the semiconductor devices or chips are subjected to a variety of electrical tests to determine if they function properly. The percent of devices on

9954-413: The era of 2 inch wafers, these were handled manually using tweezers and held manually for the time required for a given process. Tweezers were replaced by vacuum wands as they generate fewer particles which can contaminate the wafers. Wafer carriers or cassettes, which can hold several wafers at once, were developed to carry several wafers between process steps, but wafers had to be individually removed from

10080-605: The eventual replacement of FinFET , most of which were based on the concept of GAAFET : horizontal and vertical nanowires, horizontal nanosheet transistors (Samsung MBCFET, Intel Nanoribbon), vertical FET (VFET) and other vertical transistors, complementary FET (CFET), stacked FET, vertical TFETs, FinFETs with III-V semiconductor materials (III-V FinFET), several kinds of horizontal gate-all-around transistors such as nano-ring, hexagonal wire, square wire, and round wire gate-all-around transistors and negative-capacitance FET (NC-FET) which uses drastically different materials. FD-SOI

10206-437: The first automatic reticle and photomask inspection tool. In 1985, KLA developed an automatic inspection tool for silicon wafers, which replaced manual microscope inspection. In 1985, SGS (now STmicroelectronics ) invented BCD, also called BCDMOS , a semiconductor manufacturing process using bipolar , CMOS and DMOS devices. Applied Materials developed the first practical multi chamber, or cluster wafer processing tool,

10332-819: The gain is shown in the graph on the right. For multiplication registers with many elements and large gains it is well modelled by the equation: P ( n ) = ( n − m + 1 ) m − 1 ( m − 1 ) ! ( g − 1 + 1 m ) m exp ⁡ ( − n − m + 1 g − 1 + 1 m )  if  n ≥ m {\displaystyle P\left(n\right)={\frac {\left(n-m+1\right)^{m-1}}{\left(m-1\right)!\left(g-1+{\frac {1}{m}}\right)^{m}}}\exp \left(-{\frac {n-m+1}{g-1+{\frac {1}{m}}}}\right)\quad {\text{ if }}n\geq m} where P

10458-438: The gate of the transistor to improve transistor density. Historically, the metal wires have been composed of aluminum . In this approach to wiring (often called subtractive aluminum ), blanket films of aluminum are deposited first, patterned, and then etched, leaving isolated wires. Dielectric material is then deposited over the exposed wires. The various metal layers are interconnected by etching holes (called " vias") in

10584-403: The high-k dielectric and then the gate metal such as Tantalum nitride whose workfunction depends on whether the transistor is NMOS or PMOS, polysilicon deposition, gate line patterning, source and drain ion implantation, dopant anneal, and silicidation of the polysilicon and the source and drain. In DRAM memories this technology was first adopted in 2015. Gate-last consisted of first depositing

10710-506: The image sensor for storage. In this device, only one pixel shift has to occur to transfer from image area to storage area; thus, shutter times can be less than a microsecond and smear is essentially eliminated. The advantage is not free, however, as the imaging area is now covered by opaque strips dropping the fill factor to approximately 50 percent and the effective quantum efficiency by an equivalent amount. Modern designs have addressed this deleterious characteristic by adding microlenses on

10836-497: The incident light. Most common types of CCDs are sensitive to near-infrared light, which allows infrared photography , night-vision devices, and zero lux (or near zero lux) video-recording/photography. For normal silicon-based detectors, the sensitivity is limited to 1.1 μm. One other consequence of their sensitivity to infrared is that infrared from remote controls often appears on CCD-based digital cameras or camcorders if they do not have infrared blockers. Cooling reduces

10962-412: The insulating material and then depositing tungsten in them with a CVD technique using tungsten hexafluoride ; this approach can still be (and often is) used in the fabrication of many memory chips such as dynamic random-access memory (DRAM), because the number of interconnect levels can be small (no more than four). The aluminum was sometimes alloyed with copper for preventing recrystallization. Gold

11088-423: The interconnect (from silicon dioxides to newer low-κ insulators). This performance enhancement also comes at a reduced cost via damascene processing, which eliminates processing steps. As the number of interconnect levels increases, planarization of the previous layers is required to ensure a flat surface prior to subsequent lithography. Without it, the levels would become increasingly crooked, extending outside

11214-467: The invention and began development programs. Fairchild's effort, led by ex-Bell researcher Gil Amelio, was the first with commercial devices, and by 1974 had a linear 500-element device and a 2D 100 × 100 pixel device. Peter Dillon, a scientist at Kodak Research Labs, invented the first color CCD image sensor by overlaying a color filter array on this Fairchild 100 x 100 pixel Interline CCD starting in 1974. Steven Sasson , an electrical engineer working for

11340-431: The large quality advantage CCDs enjoyed early on has narrowed over time and since the late 2010s CMOS sensors are the dominant technology, having largely if not completely replaced CCD image sensors. The basis for the CCD is the metal–oxide–semiconductor (MOS) structure, with MOS capacitors being the basic building blocks of a CCD, and a depleted MOS structure used as the photodetector in early CCD devices. In

11466-411: The late 1960s, Willard Boyle and George E. Smith at Bell Labs were researching MOS technology while working on semiconductor bubble memory . They realized that an electric charge was the analogy of the magnetic bubble and that it could be stored on a tiny MOS capacitor. As it was fairly straightforward to fabricate a series of MOS capacitors in a row, they connected a suitable voltage to them so that

11592-467: The multiplied electrons back to photons which are guided to the CCD by a fiber optic or a lens. An image intensifier inherently includes a shutter functionality: If the control voltage between the photocathode and the MCP is reversed, the emitted photoelectrons are not accelerated towards the MCP but return to the photocathode. Thus, no electrons are multiplied and emitted by the MCP, no electrons are going to

11718-530: The name of its 10 nm process to position it as a 7 nm process. As transistors become smaller, new effects start to influence design decisions such as self-heating of the transistors, and other effects such as electromigration have become more evident since the 16nm node. In 2011, Intel demonstrated Fin field-effect transistors (FinFETs), where the gate surrounds the channel on three sides, allowing for increased energy efficiency and lower gate delay—and thus greater performance—over planar transistors at

11844-591: The next several years. Many early semiconductor device manufacturers developed and built their own equipment such as ion implanters. In 1963, Harold M. Manasevit was the first to document epitaxial growth of silicon on sapphire while working at the Autonetics division of North American Aviation (now Boeing ). In 1964, he published his findings with colleague William Simpson in the Journal of Applied Physics . In 1965, C.W. Mueller and P.H. Robinson fabricated

11970-443: The node with the highest transistor density is TSMC's 5   nanometer N5 node, with a density of 171.3   million transistors per square millimeter. In 2019, Samsung and TSMC announced plans to produce 3 nanometer nodes. GlobalFoundries has decided to stop the development of new nodes beyond 12 nanometers in order to save resources, as it has determined that setting up a new fab to handle sub-12 nm orders would be beyond

12096-474: The number of defects caused by dust particles. Also, fabs have as few people as possible in the cleanroom to make maintaining the cleanroom environment easier, since people, even when wearing cleanroom suits, shed large amounts of particles, especially when walking. A typical wafer is made out of extremely pure silicon that is grown into mono-crystalline cylindrical ingots ( boules ) up to 300 mm (slightly less than 12 inches) in diameter using

12222-413: The other in the mentioned sequence. The photons which are coming from the light source fall onto the photocathode, thereby generating photoelectrons. The photoelectrons are accelerated towards the MCP by an electrical control voltage, applied between photocathode and MCP. The electrons are multiplied inside of the MCP and thereafter accelerated towards the phosphor screen. The phosphor screen finally converts

12348-491: The output of the CCD, and this must be taken into consideration in satellites using CCDs. The photoactive region of a CCD is, generally, an epitaxial layer of silicon . It is lightly p doped (usually with boron ) and is grown upon a substrate material, often p++. In buried-channel devices, the type of design utilized in most modern CCDs, certain areas of the surface of the silicon are ion implanted with phosphorus , giving them an n-doped designation. This region defines

12474-450: The output of the charge amplifier into a low-pass filter), which is then processed and fed out to other circuits for transmission, recording, or other processing. Before the MOS capacitors are exposed to light, they are biased into the depletion region; in n-channel CCDs, the silicon under the bias gate is slightly p -doped or intrinsic. The gate is then biased at a positive potential, above

12600-407: The phosphor screen and no light is emitted from the image intensifier. In this case no light falls onto the CCD, which means that the shutter is closed. The process of reversing the control voltage at the photocathode is called gating and therefore ICCDs are also called gateable CCD cameras. Besides the extremely high sensitivity of ICCD cameras, which enable single photon detection, the gateability

12726-615: The process' minimum feature size in nanometers (or historically micrometers ) of the process's transistor gate length, such as the " 90 nm process ". However, this has not been the case since 1994, and the number of nanometers used to name process nodes (see the International Technology Roadmap for Semiconductors ) has become more of a marketing term that has no standardized relation with functional feature sizes or with transistor density (number of transistors per unit area). Initially transistor gate length

12852-509: The results of their work circulated around Bell Labs before being formally published in 1957. At Shockley Semiconductor , Shockley had circulated the preprint of their article in December 1956 to all his senior staff, including Jean Hoerni , who would later invent the planar process in 1959 while at Fairchild Semiconductor . In 1948, Bardeen patented an insulated-gate transistor (IGFET) with an inversion layer, Bardeen's concept, forms

12978-469: The same time but without the capability to create vertical walls. Plasma ALE was initially adopted for etching contacts in transistors, and since the 7nm node it is also used to create transistor structures by etching them. Front-end surface engineering is followed by growth of the gate dielectric (traditionally silicon dioxide ), patterning of the gate, patterning of the source and drain regions, and subsequent implantation or diffusion of dopants to obtain

13104-455: The standard until the introduction of 300 mm diameter wafers in 2000. Bridge tools were used in the transition from 150 mm wafers to 200 mm wafers and in the transition from 200 mm to 300 mm wafers. The semiconductor industry has adopted larger wafers to cope with the increased demand for chips as larger wafers provide more surface area per wafer. Over time, the industry shifted to 300 mm wafers which brought along

13230-406: The surface of the device to direct light away from the opaque regions and on the active area. Microlenses can bring the fill factor back up to 90 percent or more depending on pixel size and the overall system's optical design. The choice of architecture comes down to one of utility. If the application cannot tolerate an expensive, failure-prone, power-intensive mechanical shutter, an interline device

13356-407: The threshold for strong inversion, which will eventually result in the creation of an n channel below the gate as in a MOSFET . However, it takes time to reach this thermal equilibrium: up to hours in high-end scientific cameras cooled at low temperature. Initially after biasing, the holes are pushed far into the substrate, and no mobile electrons are at or near the surface; the CCD thus operates in

13482-505: The time 150 mm wafers arrived, the cassettes were not dipped and were only used as wafer carriers and holders to store wafers, and robotics became prevalent for handling wafers. With 200 mm wafers manual handling of wafer cassettes becomes risky as they are heavier. In the 1970s, several companies migrated their semiconductor manufacturing technology from bipolar to CMOS technology. Semiconductor manufacturing equipment has been considered costly since 1978. In 1984, KLA developed

13608-456: The total usable integration time. The accumulation of electrons at or near the surface can proceed either until image integration is over and charge begins to be transferred, or thermal equilibrium is reached. In this case, the well is said to be full. The maximum capacity of each well is known as the well depth, typically about 10 electrons per pixel. CCDs are normally susceptible to ionizing radiation and energetic particles which causes noise in

13734-611: The transition from 200 mm to 300 mm wafers in 2001, many bridge tools were used which could process both 200 mm and 300 mm wafers. At the time, 18 companies could manufacture chips in the leading edge 130nm process. In 2006, 450 mm wafers were expected to be adopted in 2012, and 675 mm wafers were expected to be used by 2021. Since 2009, "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 process

13860-559: The transport of wafers from machine to machine. A wafer often has several integrated circuits which are called dies as they are pieces diced from a single wafer. Individual dies are separated from a finished wafer in a process called die singulation , also called wafer dicing. The dies can then undergo further assembly and packaging. Within fabrication plants, the wafers are transported inside special sealed plastic boxes called FOUPs . FOUPs in many fabs contain an internal nitrogen atmosphere which helps prevent copper from oxidizing on

13986-504: The two types of transistors separately and then stacked them. This is a list of processing techniques that are employed numerous times throughout the construction of a modern electronic device; this list does not necessarily imply a specific order, nor that all techniques are taken during manufacture as, in practice the order and which techniques are applied, are often specific to process offerings by foundries, or specific to an integrated device manufacturer (IDM) for their own products, and

14112-478: The various processing steps. For example, thin film metrology based on ellipsometry or reflectometry is used to tightly control the thickness of gate oxide, as well as the thickness, refractive index, and extinction coefficient of photoresist and other coatings. Wafer metrology equipment/tools, or wafer inspection tools are used to verify that the wafers haven't been damaged by previous processing steps up until testing; if too many dies on one wafer have failed,

14238-442: The wafers. Copper is used in modern semiconductors for wiring. The insides of the processing equipment and FOUPs is kept cleaner than the surrounding air in the cleanroom. This internal atmosphere is known as a mini-environment and helps improve yield which is the amount of working devices on a wafer. This mini environment is within an EFEM (equipment front end module) which allows a machine to receive FOUPs, and introduces wafers from

14364-422: The world economy and the national security of some countries. The US has asked TSMC to not produce semiconductors for Huawei, a Chinese company. CFET transistors were explored, which stacks NMOS and PMOS transistors on top of each other. Two approaches were evaluated for constructing these transistors: a monolithic approach which built both types of transistors in one process, and a sequential approach which built

14490-738: The world. Samsung Electronics , the world's largest manufacturer of semiconductors, has facilities in South Korea and the US. Intel , the second-largest manufacturer, has facilities in Europe and Asia as well as the US. TSMC , the world's largest pure play foundry , has facilities in Taiwan, China, Singapore, and the US. Qualcomm and Broadcom are among the biggest fabless semiconductor companies, outsourcing their production to companies like TSMC. They also have facilities spread in different countries. As

14616-554: Was a simple 8-bit shift register, reported by Tompsett, Amelio and Smith in August 1970. This device had input and output circuits and was used to demonstrate its use as a shift register and as a crude eight pixel linear imaging device. Development of the device progressed at a rapid rate. By 1971, Bell researchers led by Michael Tompsett were able to capture images with simple linear devices. Several companies, including Fairchild Semiconductor , RCA and Texas Instruments , picked up on

14742-479: Was addressed. Today, frame-transfer is usually chosen when an interline architecture is not available, such as in a back-illuminated device. CCDs containing grids of pixels are used in digital cameras , optical scanners , and video cameras as light-sensing devices. They commonly respond to 70 percent of the incident light (meaning a quantum efficiency of about 70 percent) making them far more efficient than photographic film , which captures only about 2 percent of

14868-429: Was also used in interconnects in early chips. More recently, as the number of interconnect levels for logic has substantially increased due to the large number of transistors that are now interconnected in a modern microprocessor , the timing delay in the wiring has become so significant as to prompt a change in wiring material (from aluminum to copper interconnect layer) alongside a change in dielectric material in

14994-450: Was demonstrated by Gil Amelio , Michael Francis Tompsett and George Smith in April 1970. This was the first experimental application of the CCD in image sensor technology, and used a depleted MOS structure as the photodetector. The first patent ( U.S. patent 4,085,456 ) on the application of CCDs to imaging was assigned to Tompsett, who filed the application in 1971. The first working CCD made with integrated circuit technology

15120-686: Was in development from at least 2004, and is a "high-resolution fiber-fed echelle spectrograph" type of design. In 2012, the MAIA instrument for astroseismology was installed. MAIA, also called the Mercator Advanced Imager for Astroseismology uses CCD to image in three passbands. Some of the technology was developed for a space telescope called the Eddington mission , which was however cancelled and thus not sent into space at that time. CCD camera A charge-coupled device ( CCD )

15246-415: Was launched in December 1976. Under the leadership of Kazuo Iwama , Sony started a large development effort on CCDs involving a significant investment. Eventually, Sony managed to mass-produce CCDs for their camcorders . Before this happened, Iwama died in August 1982. Subsequently, a CCD chip was placed on his tombstone to acknowledge his contribution. The first mass-produced consumer CCD video camera ,

15372-513: Was not as big of an issue as it is today in device manufacturing. In the 1960s, workers could work on semiconductor devices in street clothing. As devices become more integrated, cleanrooms must become even cleaner. Today, fabrication plants are pressurized with filtered air to remove even the smallest particles, which could come to rest on the wafers and contribute to defects. The ceilings of semiconductor cleanrooms have fan filter units (FFUs) at regular intervals to constantly replace and filter

15498-466: Was seen as a potential low cost alternative to FinFETs. As of 2019, 14 nanometer and 10 nanometer chips are in mass production by Intel, UMC , TSMC, Samsung, Micron , SK Hynix , Toshiba Memory and GlobalFoundries, with 7 nanometer process chips in mass production by TSMC and Samsung, although their 7 nanometer node definition is similar to Intel's 10 nanometer process. The 5 nanometer process began being produced by Samsung in 2018. As of 2019,

15624-475: Was similar to Intel's 10 nm process , thus the conventional notion of a process node has become blurred. Additionally, TSMC and Samsung's 10 nm processes are only slightly denser than Intel's 14 nm in transistor density. They are actually much closer to Intel's 14 nm process than they are to Intel's 10 nm process (e.g. Samsung's 10 nm processes' fin pitch is the exact same as that of Intel's 14 nm process: 42 nm). Intel has changed

15750-666: Was smaller than that suggested by the process node name (e.g. 350 nm node); however this trend reversed in 2009. Feature sizes can have no connection to the nanometers (nm) used in marketing. For example, Intel's former 10 nm process actually has features (the tips of FinFET fins) with a width of 7 nm, so the Intel 10 nm process is similar in transistor density to TSMC 's 7 nm process . As another example, GlobalFoundries' 12 and 14 nm processes have similar feature sizes. In 1955, Carl Frosch and Lincoln Derick, working at Bell Telephone Laboratories , accidentally grew

15876-413: Was the first to adopt copper interconnects. In 2014, Applied Materials proposed the use of cobalt in interconnects at the 22nm node, used for encapsulating copper interconnects in cobalt to prevent electromigration, replacing tantalum nitride since it needs to be thicker than cobalt in this application. The highly serialized nature of wafer processing has increased the demand for metrology in between

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