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83-444: Stepper is short for step-and-repeat camera. The stepper emerged in the late 1970s but did not become widespread until the 1980s. This was because it was replacing an earlier technology, the mask aligner . Aligners imaged the entire surface of a wafer at the same time, producing many chips in a single operation. In contrast, the stepper imaged only one chip at a time, and was thus much slower to operate. The stepper eventually displaced

166-447: A blank silicon wafer . Elements of the circuit to be created on the IC are reproduced in a pattern of transparent and opaque areas on the surface of a glass or plastic plate called a photomask or reticle. The wafer is coated with a photosensitive material called photoresist . The mask is positioned over the wafer and bright light, normally ultraviolet , is shone through the mask. Exposure to

249-420: A ceramic plate. It was also used to etch holes in the silicon dioxide (SiO 2 ) layers to microfabricate diode arrays. Later, in 1959, Lathrop went to Texas Instruments , working for Jack Kilby , and Nall joined Fairchild Semiconductor . 1958: Based on their works, Jay Last and Robert Noyce at Fairchild Semiconductor built one of the first «step-and-repeat» cameras that repeated identical patterns of

332-438: A few well-defined directions. Scoring the wafer along cleavage planes allows it to be easily diced into individual chips (" dies ") so that the billions of individual circuit elements on an average wafer can be separated into many individual circuits. Wafers under 200 mm diameter have flats cut into one or more sides indicating the crystallographic planes of the wafer (usually a {110} face). In earlier-generation wafers

415-480: A group consisting of New York State ( SUNY Poly / College of Nanoscale Science and Engineering (CNSE)), Intel, TSMC, Samsung, IBM, Globalfoundries and Nikon companies has formed a public-private partnership called Global 450mm Consortium (G450C, similar to SEMATECH ) who made a 5-year plan (expiring in 2016) to develop a "cost effective wafer fabrication infrastructure, equipment prototypes and tools to enable coordinated industry transition to 450mm wafer level". In

498-432: A metric ton) and take 2–4 times longer to cool, and the process time will be double. All told, the development of 450 mm wafers requires significant engineering, time, and cost to overcome. In order to minimize the cost per die , manufacturers wish to maximize the number of dies that can be made from a single wafer; dies always have a square or rectangular shape due to the constraint of wafer dicing . In general, this

581-401: A one-to-one magnification, which limited the amount of detail on the wafer to about whatever could be produced on the mask. As feature sizes shrank, following Moore's law , the construction of these complex multi-chip masks became very difficult. In 1975, GCA introduced the first step-and-scan camera, which simplified the process of making masks. In this system, a single parent mask, known as

664-567: A pair of flats at different angles additionally conveyed the doping type (see illustration for conventions). Wafers of 200 mm diameter and above use a single small notch to convey wafer orientation, with no visual indication of doping type. 450 mm wafers are notchless, relying on a laser scribed structure on the wafer surface for orientation. Silicon wafers are generally not 100% pure silicon, but are instead formed with an initial impurity doping concentration between 10 and 10 atoms per cm of boron , phosphorus , arsenic , or antimony which

747-469: A purity of 99.9999999% ( 9N ) or higher. One process for forming crystalline wafers is known as the Czochralski method , invented by Polish chemist Jan Czochralski . In this process, a cylindrical ingot of high purity monocrystalline semiconductor, such as silicon or germanium , called a boule , is formed by pulling a seed crystal from a melt . Donor impurity atoms, such as boron or phosphorus in

830-489: A silicon wafer of the same diameter. Wafer thickness is determined by the mechanical strength of the material used; the wafer must be thick enough to support its own weight without cracking during handling. The tabulated thicknesses relate to when that process was introduced, and are not necessarily correct currently, for example the IBM BiCMOS7WL process is on 8-inch wafers, but these are only 200 μm thick. The weight of

913-430: A single run. More importantly, by focussing the light source onto a single area of the wafer, the stepper can produce much higher resolutions, thus allowing for smaller features on chips ( minimum feature size ). The disadvantage to the stepper is that each chip on the wafer has to be individually imaged, and thus the process of exposing the wafer as a whole is much slower. This computer-engineering -related article

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996-573: A stepper system with a scanner that images only a portion of the mask at a time. Doing so allows much better focus over the tiny part of the mask, although it also makes the IC production process much slower. As of 2008, step-and-scan systems are the most widely used systems for high-end semiconductor device fabrication . A typical stepper has the following subassemblies: wafer loader, wafer stage, wafer alignment system, reticle loader, reticle stage, reticle alignment system, reduction lens, and illumination system. Process programs for each layer printed on

1079-407: A stepper, to resolve narrow lines is limited by the wavelength of the light used for illumination, the ability of the lens to capture light (or actually orders of diffraction ) coming at increasingly wider angles (called numerical aperture or N.A.), and various improvements in the process itself. This is expressed by the following equation: C D {\displaystyle \mathrm {CD} }

1162-443: A wafer exists commercially, does not imply in any way that processing equipment to produce chips on that wafer exists, indeed such equipment tends to lag development until paying end customer demand materializes. Even after equipment is developed (years), it can take further years for fabs to figure out how to use the machines productively. A unit of wafer fabrication step, such as an etch step, can produce more chips proportional to

1245-403: A wavelength of 193 nm. Although fluoride (F2) lasers are available that produce 157 nm light, they are not practical because of their low power and because they quickly degrade photoresist and other materials used in the stepper. Since practical light sources with wavelengths narrower than these lasers have not been available, manufacturers have sought to improve resolution by reducing

1328-409: Is 100–200 mm square and the thickness is 100–500 μm. Electronics use wafer sizes from 100 to 450 mm diameter. The largest wafers made have a diameter of 450 mm, but are not yet in general use. Wafers are cleaned with weak acids to remove unwanted particles. There are several standard cleaning procedures to make sure the surface of a silicon wafer contains no contamination. One of

1411-418: Is 6 inches square and has a usable area of 104mm by 132mm. A variety of reticles, each appropriate for one stage in the process, are contained in a rack in the reticle loader , usually located at the upper front of the stepper. Before the wafer is exposed a reticle is loaded onto the reticle stage by a robot, where it is also very precisely aligned. Since the same reticle can be used to expose many wafers, it

1494-399: Is a computationally complex problem with no analytical solution, dependent on both the area of the dies as well as their aspect ratio (square or rectangular) and other considerations such as the width of the scribeline or saw lane, and additional space occupied by alignment and test structures . (By simplifying the problem so that the scribeline and saw lane are both zero-width, the wafer

1577-425: Is a stub . You can help Misplaced Pages by expanding it . Silicon wafer In electronics , a wafer (also called a slice or substrate ) is a thin slice of semiconductor , such as a crystalline silicon (c-Si, silicium), used for the fabrication of integrated circuits and, in photovoltaics , to manufacture solar cells . The wafer serves as the substrate for microelectronic devices built in and upon

1660-523: Is a function of the maximum angle of light that can enter the lens and the refractive index of the medium through which the light passes. When water is employed as the medium, it greatly increases numerical aperture, since it has a refractive index of 1.44 at 193 nm, while air has an index of 1.0003. Current production machines employing this technology are capable of resolving lines in the 32 nm range, and may eventually be able to achieve lines of 30 nm. Modern scanners are steppers that increase

1743-424: Is a system that produces integrated circuits (IC) using the photolithography process. It holds the photomask over the silicon wafer while a bright light is shone through the mask and onto the photoresist . The "alignment" refers to the ability to place the mask over precisely the same location repeatedly as the chip goes through multiple rounds of lithography. Aligners were a major part of IC manufacture from

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1826-485: Is added to the melt and defines the wafer as either bulk n-type or p-type. However, compared with single-crystal silicon's atomic density of 5×10 atoms per cm , this still gives a purity greater than 99.9999%. The wafers can also be initially provided with some interstitial oxygen concentration. Carbon and metallic contamination are kept to a minimum. Transition metals , in particular, must be kept below parts per billion concentrations for electronic applications. There

1909-476: Is considerable resistance to the 450 mm transition despite the possible productivity improvement, because of concern about insufficient return on investment. There are also issues related to increased inter-die / edge-to-edge wafer variation and additional edge defects. 450mm wafers are expected to cost 4 times as much as 300mm wafers, and equipment costs are expected to rise by 20 to 50%. Higher cost semiconductor fabrication equipment for larger wafers increases

1992-505: Is different from silicon substrate as the substrate is sapphire, while superstrate is silicon, while epitaxal layers and doping can be anything. SOS in commercial production is typically maxed out at 150 mm wafer sizes as of 2024. GaAs wafers tend to be 150 mm at largest, in commercial production as of 2024. AlN tends to be 50 mm or 2 inch wafers in commercial production, while 100 mm or 4 inch wafers are being developed as of 2024 by wafer suppliers like Asahi Kasei. However, merely because

2075-414: Is loaded once before a series of wafers is exposed, and is realigned periodically. Once the wafer and reticle are in place and aligned, the wafer stage, which is moved very precisely in the X and Y directions (front to back and left to right) by worm screws or linear motors , carries the wafer so that the first of the many patterns (or "shots") to be exposed on it is located below the lens, directly under

2158-494: Is perfectly circular with no flats, and the dies have a square aspect ratio, we arrive at the Gauss Circle Problem , an unsolved open problem in mathematics.) Note that formulas estimating the gross dies per wafer ( DPW ) account only for the number of complete dies that can fit on the wafer; gross DPW calculations do not account for yield loss among those complete dies due to defects or parametric issues. Nevertheless,

2241-423: Is related to wafer count, not wafer area. Cost for processes such as lithography is proportional to wafer area, and larger wafers would not reduce the lithography contribution to die cost. Nikon planned to deliver 450-mm lithography equipment in 2015, with volume production in 2017. In November 2013 ASML paused development of 450-mm lithography equipment, citing uncertain timing of chipmaker demand. In 2012,

2324-413: Is sawn apart into individual chips, tested, and packaged for sale. Before steppers, wafers were exposed using mask aligners , which patterned the entire wafer at once. Masks for these systems would contain many individual ICs patterned across the mask. Between each step, the operator would use a microscope to align the wafer with the next mask to be applied. During the 1970s, aligners generally worked at

2407-417: Is scanned across the exposure area. There are several benefits to this technique. The field can be exposed with a lesser reduction of size from the reticle to the wafer (such as 4x reduction on a scanner, compared with 5x reduction on a stepper), while allowing a field size much larger than that which can be exposed with a typical stepper. Also the optical properties of the projection lens can be optimized in

2490-404: Is the critical dimension, or finest line resolvable, k 1 {\displaystyle k_{1}} is a coefficient expressing process-related factors, λ {\displaystyle \lambda } is the wavelength of the light, and N A {\displaystyle \mathrm {NA} } is the numerical aperture. Decreasing the wavelength of the light in

2573-586: The Czochralski method . Silicon wafers were first introduced in the 1940s. By 1960, silicon wafers were being manufactured in the U.S. by companies such as MEMC / SunEdison . In 1965, American engineers Eric O. Ernst, Donald J. Hurd, and Gerard Seeley, while working under IBM , filed Patent US3423629A for the first high-capacity epitaxial apparatus. Silicon wafers are made by companies such as Sumco , Shin-Etsu Chemical , Hemlock Semiconductor Corporation and Siltronic . Wafers are formed of highly pure, nearly defect-free single crystalline material, with

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2656-416: The reticle , was produced at large scale so it could be mechanically robust. This was imaged through a photographic projector, shrinking the projected image 5 to 10 times. The mechanism imaged the reticle onto a photographic plate, moved the reticle to another position, and repeated this process. The result was a mask containing many precise images of the original reticle pattern. GCA continued development of

2739-433: The 1960s into the late 1970s, when they began to be replaced by the stepper . Currently, mask aligners are still used in academia and research, as projects often involve devices made using photolithography in smaller batches. In a mask aligner, there is a one-to-one correspondence between the mask pattern and the wafer pattern. The mask covers the entire surface of the wafer which is exposed in its entirety in one shot. This

2822-507: The 200 mm wafers, partly because a FOUP for 300 mm wafers weighs about 7.5 kilograms when loaded with 25 300 mm wafers where a SMIF weighs about 4.8 kilograms when loaded with 25 200 mm wafers, thus requiring twice the amount of physical strength from factory workers, and increasing fatigue. 300mm FOUPs have handles so that they can be still be moved by hand. 450mm FOUPs weigh 45 kilograms when loaded with 25 450 mm wafers, thus cranes are necessary to manually handle

2905-559: The 2000s. Today, step-and-scan systems are so widespread that they are often simply referred to as steppers. An example of a step-and-scan system is the PAS 5500 from ASML . 1957: Attempts to miniaturize electronic circuits started back in 1957 when Jay Lathrop and James Nall of the U.S. Army's Diamond Ordnance Fuze Laboratories were granted a US2890395A patent for a photolithographic technique that could be used to deposit thin-film metal strips that in turn used to connect discrete transistors on

2988-507: The FOUPs and handles are no longer present in the FOUP. FOUPs are moved around using material handling systems from Muratec or Daifuku . These major investments were undertaken in the economic downturn following the dot-com bubble , resulting in huge resistance to upgrading to 450 mm by the original timeframe. On the ramp-up to 450 mm, the crystal ingots will be 3 times heavier (total weight

3071-513: The M10 standard (182 mm) are ongoing. Like other semiconductor fabrication processes, driving down costs has been the main driving factor for this attempted size increase, in spite of the differences in the manufacturing processes of different types of devices. Wafers are grown from crystal having a regular crystal structure , with silicon having a diamond cubic structure with a lattice spacing of 5.430710 Å (0.5430710 nm). When cut into wafers,

3154-462: The ability to produce increasingly finer lines on the surface of the wafer has been the wavelength of the light used in the exposure system. As the required lines have become narrower and narrower, illumination sources producing light with progressively shorter wavelengths have been put into service in steppers and scanners. An alternative to conventional light based lithography is nanoimprint lithography . The ability of an exposure system, such as

3237-410: The aligner when the relentless forces of Moore's Law demanded that smaller feature sizes be used. Because the stepper imaged only one chip at a time it offered higher resolution and was the first technology to exceed the 1 micron limit. The addition of auto-alignment systems reduced the setup time needed to image multiple ICs, and by the late 1980s, the stepper had almost entirely replaced the aligner in

3320-464: The area through which the image of the projection slit passes, while optical aberrations can be ignored outside of this area, because they will not affect the exposed area on the wafer. Successful scanning requires extremely precise synchronization between the moving reticle and wafer stages during the exposure. Accomplishing this presents many technological challenges. Stepper makers : Aligner (semiconductor) An aligner , or mask aligner ,

3403-436: The case of silicon, can be added to the molten intrinsic material in precise amounts in order to dope the crystal, thus changing it into an extrinsic semiconductor of n-type or p-type . The boule is then sliced with a wafer saw (a type of wire saw ), machined to improve flatness, chemically etched to remove crystal damage from machining steps and finally polished to form wafers. The size of wafers for photovoltaics

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3486-434: The cost of 450 mm fabs (semiconductor fabrication facilities or factories). Lithographer Chris Mack claimed in 2012 that the overall price per die for 450 mm wafers would be reduced by only 10–20% compared to 300 mm wafers, because over 50% of total wafer processing costs are lithography-related. Converting to larger 450 mm wafers would reduce price per die only for process operations such as etch where cost

3569-439: The desired line widths approached and eventually became narrower than the wavelength of the light used to create them, a variety of resolution enhancement techniques were developed to make this possible, such as phase shifting reticles and various techniques for manipulating the angles of the exposure light in order to maximize the resolving power of the lens. Eventually however, the desired line widths became narrower than what

3652-466: The diameter of wafers that they are tooled to produce. The diameter has gradually increased to improve throughput and reduce cost with the current state-of-the-art fab using 300 mm , with a proposal to adopt 450 mm . Intel , TSMC , and Samsung were separately conducting research to the advent of 450 mm " prototype " (research) fabs , though serious hurdles remain. Wafers grown using materials other than silicon will have different thicknesses than

3735-418: The edge correction is negligible. The correction factor or correction term generally takes one of the forms cited by De Vries: Studies comparing these analytical formulas to brute-force computational results show that the formulas can be made more accurate, over practical ranges of die sizes and aspect ratios, by adjusting the coefficients of the corrections to values above or below unity, and by replacing

3818-500: The end of this decade). Mark LaPedus of semiengineering.com reported in mid-2014 that chipmakers had delayed adoption of 450 mm "for the foreseeable future." According to this report some observers expected 2018 to 2020, while G. Dan Hutcheson, chief executive of VLSI Research, didn't see 450mm fabs moving into production until 2020 to 2025. The step up to 300 mm required major changes, with fully automated factories using 300 mm wafers versus barely automated factories for

3901-465: The extent that it does, it's a long way out in the future. There is not a lot of necessity for Micron, at least over the next five years, to be spending a lot of money on 450mm." "There is a lot of investment that needs to go on in the equipment community to make that happen. And the value at the end of the day – so that customers would buy that equipment – I think is dubious." As of March 2014, Intel Corporation expected 450 mm deployment by 2020 (by

3984-522: The fact that the 300mm manufacturing optimization is more cheap than costly 450mm transition may also have played a role. The timeline for 450 mm has not been fixed. In 2012, it was expected that 450mm production would start in 2017, which never realized. Mark Durcan, then CEO of Micron Technology , said in February 2014 that he expects 450 mm adoption to be delayed indefinitely or discontinued. "I am not convinced that 450mm will ever happen but, to

4067-497: The first successful stepper, the DSW 4800 , in 1975. It could reach critical dimensions of 1 micron, better than any other system at the time. Integrated circuits (ICs) are produced in a process known as photolithography. The process starts with a large highly purified cylindrical crystal of the semiconductor material known as a boule . Thin slices are cut off the boule to form disks, and then undergo initial processing and treatment to create

4150-485: The following parts: The projection aligner is similar to the wafer stepper in concept, but with one key difference. The aligner uses a mask that holds the pattern for the entire wafer, which may require large masks. The stepper uses a smaller mask on the wafer repeatedly, and steps across the surface to repeat the pattern of the chip layer. This reduces mask costs dramatically and allows a single wafer to be used for different integrated circuit layouts or mask designs in

4233-407: The hardware as a direct-to-wafer system, eliminating the need to produce a mask from the reticle and instead using the reticle to expose the wafer directly. Because the reticle was at a much larger scale than the final image, the resolution could be improved, as this was formerly limited to the resolution of the mask itself. To pattern the entire wafer, the mask is repeatedly moved, or stepped , across

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4316-416: The high-end market. The stepper was itself replaced by the step-and-scan systems (scanners) which offered an additional order of magnitude resolution advance. Step-and-scan systems work by scanning only a small portion of the mask for an individual IC, and thus require much longer operation times than the original steppers. Step-and-scan systems became widespread during the 1990s and essentially universal by

4399-420: The illumination system increases the resolving power of the stepper. Twenty years ago, the "g-line" (436 nm) of the mercury spectrum was used to create lines in the 750 nm range in steppers that employed mercury lamps as their illumination source. Several years later systems employing the ultraviolet "i-line" (365 nm) from mercury lamps were introduced to create lines as low as 350 nm. As

4482-554: The increase in wafer area, while the cost of the unit fabrication step goes up more slowly than the wafer area. This was the cost basis for increasing wafer size. Conversion to 300 mm wafers from 200 mm wafers began in early 2000, and reduced the price per die for about 30–40%. Larger diameter wafers allow for more die per wafer. M1 wafer size (156.75 mm) is in the process of being phased out in China as of 2020. Various nonstandard wafer sizes have arisen, so efforts to fully adopt

4565-415: The length of the area exposed in each shot (the exposure field) by moving the reticle stage and wafer stage in opposite directions to each other during the exposure. Instead of exposing the entire field at once, the exposure is made through an "exposure slit" that is as wide as the exposure field, but only a fraction of its length (such as a 9x25 mm slit for a 35x25 mm field). The image from the exposure slit

4648-439: The light causes sections of the resist to either harden or soften, depending on the process. After exposure, the wafer is developed like photographic film, causing the photoresist to dissolve in certain areas according to the amount of light the areas received during exposure. These areas of photoresist and no photoresist reproduce the pattern on the reticle. The developed wafer is then exposed to solvents . The solvent etches away

4731-434: The linear die dimension S {\displaystyle {\sqrt {S}}} with ( H + W ) / 2 {\displaystyle (H+W)/2} (average side length) in the case of dies with large aspect ratio: While silicon is the prevalent material for wafers used in the electronics industry , other compound III-V or II-VI materials have also been employed. Gallium arsenide (GaAs),

4814-416: The lower front of the stepper. A robot in the wafer loader picks up one of the wafers from the cassette and loads it onto the wafer stage where it is aligned to enable another, finer alignment process that will occur later on. The pattern of the circuitry for each chip is contained in a pattern etched in chrome on the reticle, which is a plate of transparent quartz . A typical reticle used in steppers

4897-538: The mid of 2014 CNSE has announced that it will reveal first fully patterned 450mm wafers at SEMICON West. In early 2017, the G450C began to dismantle its activities over 450mm wafer research due to undisclosed reasons. Various sources have speculated that demise of the group came after charges of bid rigging made against Alain E. Kaloyeros , who at the time was a chief executive at the SUNY Poly. The industry realization of

4980-528: The most effective methods is the RCA clean . When used for solar cells , the wafers are textured to create a rough surface to increase surface area and so their efficiency. The generated PSG ( phosphosilicate glass ) is removed from the edge of the wafer in the etching . Silicon wafers are available in a variety of diameters from 25.4 mm (1 inch) to 300 mm (11.8 inches). Semiconductor fabrication plants , colloquially known as fabs , are defined by

5063-443: The number of gross DPW can be estimated starting with the first-order approximation or floor function of wafer-to-die area ratio, where This formula simply states that the number of dies which can fit on the wafer cannot exceed the area of the wafer divided by the area of each individual die. It will always overestimate the true best-case gross DPW, since it includes the area of partially patterned dies which do not fully lie on

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5146-457: The numerical aperture. However, these techniques are approaching their practical limit, and line widths in the 45 nm range appear to be near the best that can be achieved with conventional design. Ultimately, other sources of illumination will have to be put to use, such as electron beams , x-rays or similar sources of electromagnetic energy with wavelengths much shorter than visible light . However, in order to delay as long as possible

5229-413: The possible resolution many times over that of the aligners and were the first systems to allow features smaller than 1 micron. However, the relentless drive of Moore's law pushed the industry to the point where even the maximum magnifications possible in the projection system were not enough to continue shrinking the feature sizes. This led to the 1990 introduction of the step-and-scan systems, which combine

5312-405: The process coefficient k 1 {\displaystyle k_{1}} . This is done by further improving techniques for manipulating the light as it passes through the illumination system and the reticle, as well as improving techniques for processing the wafer before and after exposure. Manufacturers have also introduced ever larger and more expensive lenses as a means of increasing

5395-422: The reticle. Although the wafer is aligned after it is placed on the wafer stage, this alignment is not sufficient to ensure that the layer of circuitry to be printed onto the wafer exactly overlays previous layers already there. Therefore, each shot is aligned using special alignment marks that are located in the pattern for each final IC chip. Once this fine alignment is completed, the shot is exposed by light from

5478-405: The silicon in the parts of the wafer that are no longer protected by the photoresist coating. Other chemicals are used to change the electrical characteristics of the silicon in the bare areas. The wafer is then cleaned, recoated with photoresist, then passed through the process again in a process that creates the circuit on the silicon, layer by layer. Once the entire process is complete, the wafer

5561-417: The stepper's illumination system that passes through the reticle, through a reduction lens , and on to the surface of the wafer. A process program or "recipe" determines the length of the exposure, the reticle used, as well as other factors that affect the exposure. Each shot located in a grid pattern on the wafer and is exposed in turn as the wafer is stepped back and forth under the lens. When all shots on

5644-541: The surface is aligned in one of several relative directions known as crystal orientations. Orientation is defined by the Miller index with (100) or (111) faces being the most common for silicon. Orientation is important since many of a single crystal's structural and electronic properties are highly anisotropic . Ion implantation depths depend on the wafer's crystal orientation, since each direction offers distinct paths for transport. Wafer cleavage typically occurs only in

5727-411: The surface of the wafer. This requires the stepping mechanism to be incredibly accurate, demanding precise alignment. The alignment process is normally automated, eliminating manual operation. As each exposure takes as long as the entire mask in an aligner, steppers are inherently slower to use than aligners, so aligners remain in use for roles where higher resolutions are not required. Steppers increased

5810-522: The surface to avoid this problem, but were difficult to work with and required considerable manual adjustment. Finally, the Micralign projection aligner , introduced by Perkin-Elmer in 1973, held the mask entirely separate from the chip and made the adjustment of the image much simpler. Through these stages of development, yields improved from perhaps 10% to about 70%, leading to a corresponding reduction in chip prices. A typical mask aligner consists of

5893-507: The transistors on a single wafer using photolithography. 1959: (Or no later 1961); The David W. Mann division of GCA Corporation became the first company to make commercial step and repeat mask reduction devices called photo-repeaters, which were the predecessors of modern day photolithography steppers. The company was later sold to GCA Corporation /Mann and Perkin Elmer. 1970: the Cobilt company

5976-424: The vast expense and difficulty of adopting a whole new type of illumination technology, manufacturers have turned to a technique, previously used in microscopes , for increasing the numerical aperture of the lens by allowing the light to pass through water instead of air . This method, called immersion lithography , is the current cutting edge of practical production technology. It works because numerical aperture

6059-423: The wafer are executed by a control system centering on a computer that stores the process program, reads it, and communicates with the various subassemblies of the stepper in carrying out the program's instructions. The components of the stepper are contained in a sealed chamber that is maintained at a precise temperature to prevent distortions in the printed patterns that might be caused by expansion or contraction of

6142-482: The wafer are exposed, the wafer is unloaded by the wafer loader robot, and another wafer takes its place on the stage. The exposed wafer is eventually moved to a developer where the photoresist on its surface is exposed to developing chemicals that wash away areas of the photoresist, based on whether or not they were exposed to the light passing through the reticle. The developed surface is then subjected to other processes of photolithography . The greatest limitation on

6225-425: The wafer due to temperature variations. The chamber also contains other systems that support the process, such as air conditioning , power supplies , control boards for the various electrical components, and others. The silicon wafers are coated with photoresist, and placed in a cassette or "boat" that holds a number of wafers. This is then placed in a part of the stepper called the wafer loader , usually located at

6308-562: The wafer increases with its thickness and the square of its diameter. Date of introduction does not indicate that factories will convert their equipment immediately, in fact, many factories do not bother upgrading. Instead, companies tend to expand and build whole new lines with newer technologies, leaving a large spectrum of technologies in use at the same time. GaN substrate wafers typically have had their own independent timelines, parallel but far lagging silicon substrate, but ahead of other substrates. The world's first 300 mm wafer made of GaN

6391-460: The wafer surface (see figure). These partially patterned dies don't represent complete ICs , so they usually cannot be sold as functional parts. Refinements of this simple formula typically add an edge correction, to account for partial dies on the edge, which in general will be more significant when the area of the die is large compared to the total area of the wafer. In the other limiting case (infinitesimally small dies or infinitely large wafers),

6474-566: The wafer. It undergoes many microfabrication processes, such as doping , ion implantation , etching , thin-film deposition of various materials, and photolithographic patterning. Finally, the individual microcircuits are separated by wafer dicing and packaged as an integrated circuit. In the semiconductor industry, the term wafer appeared in the 1950s to describe a thin round slice of semiconductor material, typically germanium or silicon. The round shape characteristic of these wafers comes from single-crystal ingots usually produced using

6557-534: Was announced in Sept 2024 by Infineon, suggesting in the coming future they could put into use the first factory with 300 mm GaN commercial output. Meanwhile world's first Silicon Carbide (SiC) 200 mm wafers were announced in July 2021 by ST Microelectronics. It is not known if SiC 200 mm has entered volume production as of 2024, as typically the largest fabs for SiC in commercial production remain at 150 mm. Silicon on sapphire

6640-520: Was founded by a group of three engineers from Germany and England (from Kasper Instruments), and one salesman Peter Wolken. The company made what would later be called wafer steppers or lithography machines, at the time referred as mask aligners . The throughput of this machine was one 2-Inches wide wafer at a time. The Cobilt, which also traded abroad and had plants in Asia (Hong-Kong, Korea, etc.), in Europe

6723-637: Was originally represented by a company called Advanced Semiconductor Materials (ASM) run by Arthur del Prado  [ nl ] in Holland , who have founded the ASML in the mid of 1960s. Around 1971 or so the Cobilt was acquired by Computervision , which had greatly automated Cobilt machine. 1973: Perkin-Elmer had introduced Micralign projection aligner. It helped to decrease amount of defective chips that resulted in low yields and greatly boosted IC industry by helping to lower prices on chips. GCA introduced

6806-425: Was possible using mercury lamps, and near the middle of the 2000s, the semiconductor industry moved towards steppers that employed krypton-fluoride (KrF) excimer lasers producing 248 nm light. Such systems are currently being used to produce lines in the 110 nm range. Lines as low as 32 nm are being resolved by production-capable steppers using argon -fluoride (ArF) excimer lasers that emit light with

6889-415: Was the standard for the 1:1 mask aligners that were succeeded by steppers and scanners with reduction optics. There are several distinct generations of aligner technology. The early contact aligners placed the mask in direct contact with the top surface of the wafer, which often damaged the pattern when the mask was lifted off again. Used only briefly, proximity aligners held the mask slightly above

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