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135-449: DRAM typically takes the form of an integrated circuit chip, which can consist of dozens to billions of DRAM memory cells. DRAM chips are widely used in digital electronics where low-cost and high-capacity computer memory is required. One of the largest applications for DRAM is the main memory (colloquially called the RAM) in modern computers and graphics cards (where the main memory

270-492: A design flow that engineers use to design, verify, and analyze entire semiconductor chips. Some of the latest EDA tools use artificial intelligence (AI) to help engineers save time and improve chip performance. Integrated circuits can be broadly classified into analog , digital and mixed signal , consisting of analog and digital signaling on the same IC. Digital integrated circuits can contain billions of logic gates , flip-flops , multiplexers , and other circuits in

405-627: A fabrication facility (commonly known as a semiconductor fab ) can cost over US$ 12 billion to construct. The cost of a fabrication facility rises over time because of increased complexity of new products; this is known as Rock's law . Such a facility features: ICs can be manufactured either in-house by integrated device manufacturers (IDMs) or using the foundry model . IDMs are vertically integrated companies (like Intel and Samsung ) that design, manufacture and sell their own ICs, and may offer design and/or manufacturing (foundry) services to other companies (the latter often to fabless companies ). In

540-410: A memory controller ; the memory controller needs to know DRAM parameters, especially memory timings , to initialize DRAMs, which may be different depending on different DRAM manufacturers and part numbers. DRAM had a 47% increase in the price-per-bit in 2017, the largest jump in 30 years since the 45% jump in 1988, while in recent years the price has been going down. In 2018, a "key characteristic of

675-412: A microprocessor will have memory on the chip. (See the regular array structure at the bottom of the first image. ) Although the structures are intricate – with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although light waves in the visible spectrum cannot be used to "expose"

810-557: A DRAM using a three-transistor cell that they had developed. This became the Intel 1102 in early 1970. However, the 1102 had many problems, prompting Intel to begin work on their own improved design, in secrecy to avoid conflict with Honeywell. This became the first commercially available DRAM, the Intel 1103 , in October 1970, despite initial problems with low yield until the fifth revision of

945-480: A Japanese patent of a memory circuit composed of several transistors and a capacitor, in 1967 they applied for a patent in the US. The earliest forms of DRAM mentioned above used bipolar transistors . While it offered improved performance over magnetic-core memory , bipolar DRAM could not compete with the lower price of the then-dominant magnetic-core memory. Capacitors had also been used for earlier memory schemes, such as

1080-466: A common active area, but there was no electrical isolation to separate them from each other. The monolithic integrated circuit chip was enabled by the inventions of the planar process by Jean Hoerni and p–n junction isolation by Kurt Lehovec . Hoerni's invention was built on Carl Frosch and Lincoln Derick's work on surface protection and passivation by silicon dioxide masking and predeposition, as well as Fuller, Ditzenberger's and others work on

1215-561: A common substrate in a three-stage amplifier arrangement. Jacobi disclosed small and cheap hearing aids as typical industrial applications of his patent. An immediate commercial use of his patent has not been reported. Another early proponent of the concept was Geoffrey Dummer (1909–2002), a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence . Dummer presented

1350-491: A few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically microprocessors , DSPs , and microcontrollers , use boolean algebra to process "one" and "zero" signals . Among the most advanced integrated circuits are the microprocessors or " cores ", used in personal computers, cell-phones, etc. Several cores may be integrated together in

1485-428: A large transistor count . The IC's mass production capability, reliability, and building-block approach to integrated circuit design have ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics . Computers, mobile phones, and other home appliances are now essential parts of

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1620-408: A layer of material, as they would be too large for the features. Thus photons of higher frequencies (typically ultraviolet ) are used to create the patterns for each layer. Because each feature is so small, electron microscopes are essential tools for a process engineer who might be debugging a fabrication process. Each device is tested before packaging using automated test equipment (ATE), in

1755-530: A leased facility located on Skyline Drive, which is part of an industrial park shared by several area businesses. In 2012 the Hawthorne lease was closed by IBM and remaining employees were relocated to the Yorktown Heights site. The Hawthorne building (located at 19 Skyline Drive) is easily recognizable by its mirrored facade and large blue pole. Located approximately 25 miles north of New York City,

1890-412: A logic one requires the wordline be driven to a voltage greater than the sum of V CC and the access transistor's threshold voltage (V TH ). This voltage is called V CC pumped (V CCP ). The time required to discharge a capacitor thus depends on what logic value is stored in the capacitor. A capacitor containing logic one begins to discharge when the voltage at the access transistor's gate terminal

2025-428: A number of steps for the p–n junction isolation of transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other. Its advantage for integrated circuits was pointed out by Dawon Kahng in 1961. The list of IEEE milestones includes the first integrated circuit by Kilby in 1958, Hoerni's planar process and Noyce's planar IC in 1959. The earliest experimental MOS IC to be fabricated

2160-420: A process known as wafer testing , or wafer probing. The wafer is then cut into rectangular blocks, each of which is called a die . Each good die (plural dice , dies , or die ) is then connected into a package using aluminium (or gold) bond wires which are thermosonically bonded to pads , usually found around the edge of the die. Thermosonic bonding was first introduced by A. Coucoulas which provided

2295-421: A rate predicted by Moore's law , leading to large-scale integration (LSI) with hundreds of transistors on a single MOS chip by the late 1960s. Following the development of the self-aligned gate (silicon-gate) MOSFET by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967, the first silicon-gate MOS IC technology with self-aligned gates , the basis of all modern CMOS integrated circuits,

2430-407: A reliable means of forming these vital electrical connections to the outside world. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Industrial CT scanning can also be used. Test cost can account for over 25% of the cost of fabrication on lower-cost products, but can be negligible on low-yielding, larger, or higher-cost devices. As of 2022 ,

2565-426: A semiconductor to modulate its electronic properties. Doping is the process of adding dopants to a semiconductor material. Since a CMOS device only draws current on the transition between logic states , CMOS devices consume much less current than bipolar junction transistor devices. A random-access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even

2700-859: A single IC or chip. Digital memory chips and application-specific integrated circuits (ASICs) are examples of other families of integrated circuits. In the 1980s, programmable logic devices were developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a chip to be programmed to do various LSI-type functions such as logic gates , adders and registers . Programmability comes in various forms – devices that can be programmed only once , devices that can be erased and then re-programmed using UV light , devices that can be (re)programmed using flash memory , and field-programmable gate arrays (FPGAs) which can be programmed at any time, including during operation. Current FPGAs can (as of 2016) implement

2835-518: A single bitline contact) from a column, then move the DRAM cells from an adjacent column into the voids. The location where the bitline twists occupies additional area. To minimize area overhead, engineers select the simplest and most area-minimal twisting scheme that is able to reduce noise under the specified limit. As process technology improves to reduce minimum feature sizes, the signal to noise problem worsens, since coupling between adjacent metal wires

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2970-407: A single chip, to accommodate more capacity without becoming too slow. When such a RAM is accessed by clocked logic, the times are generally rounded up to the nearest clock cycle. For example, when accessed by a 100 MHz state machine (i.e. a 10 ns clock), the 50 ns DRAM can perform the first read in five clock cycles, and additional reads within the same page every two clock cycles. This

3105-532: A single die. A technique has been demonstrated to include microfluidic cooling on integrated circuits, to improve cooling performance as well as peltier thermoelectric coolers on solder bumps, or thermal solder bumps used exclusively for heat dissipation, used in flip-chip . The cost of designing and developing a complex integrated circuit is quite high, normally in the multiple tens of millions of dollars. Therefore, it only makes economic sense to produce integrated circuit products with high production volume, so

3240-495: A single layer on one side of a chip of silicon in a flat two-dimensional planar process . Researchers have produced prototypes of several promising alternatives, such as: As it becomes more difficult to manufacture ever smaller transistors, companies are using multi-chip modules / chiplets , three-dimensional integrated circuits , package on package , High Bandwidth Memory and through-silicon vias with die stacking to increase performance and reduce size, without having to reduce

3375-486: A six-pin device. Radios with the Loewe 3NF were less expensive than other radios, showing one of the advantages of integration over using discrete components , that would be seen decades later with ICs. Early concepts of an integrated circuit go back to 1949, when German engineer Werner Jacobi ( Siemens AG ) filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on

3510-462: A time determined by an external timer function that governs the operation of the rest of a system, such as the vertical blanking interval that occurs every 10–20 ms in video equipment. The row address of the row that will be refreshed next is maintained by external logic or a counter within the DRAM. A system that provides the row address (and the refresh command) does so to have greater control over when to refresh and which row to refresh. This

3645-444: A value is read, modified, and then written back as a single, indivisible operation (Jacob, p. 459). The one-transistor, zero-capacitor (1T, or 1T0C) DRAM cell has been a topic of research since the late-1990s. 1T DRAM is a different way of constructing the basic DRAM memory cell, distinct from the classic one-transistor/one-capacitor (1T/1C) DRAM cell, which is also sometimes referred to as 1T DRAM , particularly in comparison to

3780-417: A very robust design for customer applications. At the 16 Kbit density, the cost advantage increased; the 16 Kbit Mostek MK4116 DRAM, introduced in 1976, achieved greater than 75% worldwide DRAM market share. However, as density increased to 64 Kbit in the early 1980s, Mostek and other US manufacturers were overtaken by Japanese DRAM manufacturers, which dominated the US and worldwide markets during

3915-418: A wide range of electronic devices, including computers , smartphones , and televisions , to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality. Integrated circuits are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing

4050-505: A year after Kilby, Robert Noyce at Fairchild Semiconductor invented the first true monolithic IC chip. More practical than Kilby's implementation, Noyce's chip was made of silicon , whereas Kilby's was made of germanium , and Noyce's was fabricated using the planar process , developed in early 1959 by his colleague Jean Hoerni and included the critical on-chip aluminum interconnecting lines. Modern IC chips are based on Noyce's monolithic IC, rather than Kilby's. NASA's Apollo Program

4185-448: Is 3-4-4-8 with a 200 MHz clock, while premium-priced high performance PC3200 DDR DRAM DIMM might be operated at 2-2-2-5 timing. Minimum random access time has improved from t RAC  = 50 ns to t RCD + t CL = 22.5 ns , and even the premium 20 ns variety is only 2.5 times faster than the asynchronous DRAM. CAS latency has improved even less, from t CAC = 13 ns to 10 ns. However,

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4320-442: Is able to offer better long-term area efficiencies; since folded array architectures require increasingly complex folding schemes to match any advance in process technology. The relationship between process technology, array architecture, and area efficiency is an active area of research. The first DRAM integrated circuits did not have any redundancy. An integrated circuit with a defective DRAM cell would be discarded. Beginning with

4455-438: Is above V CCP . If the capacitor contains a logic zero, it begins to discharge when the gate terminal voltage is above V TH . Up until the mid-1980s, the capacitors in DRAM cells were co-planar with the access transistor (they were constructed on the surface of the substrate), thus they were referred to as planar capacitors. The drive to increase both density and, to a lesser extent, performance, required denser designs. This

4590-401: Is called the graphics memory ). It is also used in many portable devices and video game consoles. In contrast, SRAM, which is faster and more expensive than DRAM, is typically used where speed is of greater concern than cost and size, such as the cache memories in processors . The need to refresh DRAM demands more complicated circuitry and timing than SRAM. This complexity is offset by

4725-413: Is done to minimize conflicts with memory accesses, since such a system has both knowledge of the memory access patterns and the refresh requirements of the DRAM. When the row address is supplied by a counter within the DRAM, the system relinquishes control over which row is refreshed and only provides the refresh command. Some modern DRAMs are capable of self-refresh; no external logic is required to instruct

4860-436: Is fully at its highest voltage and the other bit-line is at the lowest possible voltage. To store data, a row is opened and a given column's sense amplifier is temporarily forced to the desired high or low-voltage state, thus causing the bit-line to charge or discharge the cell storage capacitor to the desired value. Due to the sense amplifier's positive feedback configuration, it will hold a bit-line at stable voltage even after

4995-403: Is given as n F, where n is a number derived from the DRAM cell design, and F is the smallest feature size of a given process technology. This scheme permits comparison of DRAM size over different process technology generations, as DRAM cell area scales at linear or near-linear rates with respect to feature size. The typical area for modern DRAM cells varies between 6–8 F. The horizontal wire,

5130-424: Is inversely proportional to their pitch. The array folding and bitline twisting schemes that are used must increase in complexity in order to maintain sufficient noise reduction. Schemes that have desirable noise immunity characteristics for a minimal impact in area is the topic of current research (Kenner, p. 37). Advances in process technology could result in open bitline array architectures being favored if it

5265-408: Is limited by its capacitance (which increases with length), which must be kept within a range for proper sensing (as DRAMs operate by sensing the charge of the capacitor released onto the bitline). Bitline length is also limited by the amount of operating current the DRAM can draw and by how power can be dissipated, since these two characteristics are largely determined by the charging and discharging of

5400-447: Is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high because the IC's components switch quickly and consume comparatively little power because of their small size and proximity. The main disadvantage of ICs

5535-621: Is named for both Thomas J. Watson, Sr. and Thomas Watson, Jr. , who led IBM as president and CEO, respectively, from 1915 when it was known as the Computing-Tabulating-Recording Company , to 1971. The research is intended to improve hardware ( physical sciences and semiconductors research), services (business modelling, consulting, and operations research), software (programming languages, security, speech recognition , data management, and collaboration tools), systems operating systems and server design, and

Dynamic random-access memory - Misplaced Pages Continue

5670-690: Is obsolete. An early attempt at combining several components in one device (like modern ICs) was the Loewe 3NF vacuum tube first made in 1926. Unlike ICs, it was designed with the purpose of tax avoidance , as in Germany, radio receivers had a tax that was levied depending on how many tube holders a radio receiver had. It allowed radio receivers to have a single tube holder. One million were manufactured, and were "a first step in integration of radioelectronic devices". The device contained an amplifier , composed of three triodes, two capacitors and four resistors in

5805-413: Is the high initial cost of designing them and the enormous capital cost of factory construction. This high initial cost means ICs are only commercially viable when high production volumes are anticipated. An integrated circuit is defined as: A circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for

5940-401: Is the time to open a row, settle the sense amplifiers, and deliver the selected column data to the output. This is also the minimum /RAS low time, which includes the time for the amplified data to be delivered back to recharge the cells. The time to read additional bits from an open page is much less, defined by the /CAS to /CAS cycle time. The quoted number is the clearest way to compare between

6075-530: Is used to support their research both in support of and beyond traditional scaling. This work is done in a collaborative ecosystem based environment which includes academic and industrial partners. The Cambridge research lab can be found at 75 Binney Street in Cambridge, Massachusetts ; it is located in the IBM Watson Health HQ. Research at Cambridge focuses on AI. The Hawthorne building was

6210-441: Is usually arranged in a rectangular array of charge storage cells consisting of one capacitor and transistor per data bit. The figure to the right shows a simple example with a four-by-four cell matrix. Some DRAM matrices are many thousands of cells in height and width. The long horizontal lines connecting each row are known as word-lines. Each column of cells is composed of two bit-lines, each connected to every other storage cell in

6345-471: The JEDEC standard. Some systems refresh every row in a burst of activity involving all rows every 64 ms. Other systems refresh one row at a time staggered throughout the 64 ms interval. For example, a system with 2 = 8,192 rows would require a staggered refresh rate of one row every 7.8 μs which is 64 ms divided by 8,192 rows. A few real-time systems refresh a portion of memory at

6480-473: The Technion – Israel Institute of Technology ), and Zvi Galil (former president of Tel Aviv University ). In 2009, the work done at the center from 1960 to 1984 was named an IEEE Milestone . As of November 2010, the center houses three TOP500 supercomputers; the oldest and still fastest of which, a BlueGene/L system designed for protein folding simulations, called BGW (Blue Gene Watson), entered

6615-476: The dual in-line package (DIP), first in ceramic and later in plastic, which is commonly cresol - formaldehyde - novolac . In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier (LCC) packages. Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by

6750-475: The masks . The 1103 was designed by Joel Karp and laid out by Pat Earhart. The masks were cut by Barbara Maness and Judy Garcia. MOS memory overtook magnetic-core memory as the dominant memory technology in the early 1970s. The first DRAM with multiplexed row and column address lines was the Mostek MK4096 4 Kbit DRAM designed by Robert Proebsting and introduced in 1973. This addressing scheme uses

6885-488: The non-recurring engineering (NRE) costs are spread across typically millions of production units. Modern semiconductor chips have billions of components, and are far too complex to be designed by hand. Software tools to help the designer are essential. Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems , including integrated circuits. The tools work together in

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7020-498: The periodic table of the chemical elements were identified as the most likely materials for a solid-state vacuum tube . Starting with copper oxide , proceeding to germanium , then silicon , the materials were systematically studied in the 1940s and 1950s. Today, monocrystalline silicon is the main substrate used for ICs although some III-V compounds of the periodic table such as gallium arsenide are used for specialized applications like LEDs , lasers , solar cells and

7155-544: The small-outline integrated circuit (SOIC) package – a carrier which occupies an area about 30–50% less than an equivalent DIP and is typically 70% thinner. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches. In the late 1990s, plastic quad flat pack (PQFP) and thin small-outline package (TSOP) packages became the most common for high pin count devices, though PGA packages are still used for high-end microprocessors . Ball grid array (BGA) packages have existed since

7290-416: The switching power consumption per transistor goes down, while the memory capacity and speed go up, through the relationships defined by Dennard scaling ( MOSFET scaling ). Because speed, capacity, and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. Over the years, transistor sizes have decreased from tens of microns in

7425-503: The very large-scale integration (VLSI) of more than 10,000 transistors on a single chip. At first, MOS-based computers only made sense when high density was required, such as aerospace and pocket calculators . Computers built entirely from TTL, such as the 1970 Datapoint 2200 , were much faster and more powerful than single-chip MOS microprocessors such as the 1972 Intel 8008 until the early 1980s. Advances in IC technology, primarily smaller features and larger chips, have allowed

7560-425: The 1970s. Flip-chip Ball Grid Array packages, which allow for a much higher pin count than other package types, were developed in the 1990s. In an FCBGA package, the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over

7695-498: The 1980s and 1990s. Early in 1985, Gordon Moore decided to withdraw Intel from producing DRAM. By 1986, many, but not all, United States chip makers had stopped making DRAMs. Micron Technology and Texas Instruments continued to produce them commercially, and IBM produced them for internal use. In 1985, when 64K DRAM memory chips were the most common memory chips used in computers, and when more than 60 percent of those chips were produced by Japanese companies, semiconductor makers in

7830-482: The 22 nm node (Intel) or 16/14 nm nodes. Mono-crystal silicon wafers are used in most applications (or for special applications, other semiconductors such as gallium arsenide are used). The wafer need not be entirely silicon. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon, insulators or metal (typically aluminium or copper) tracks deposited on them. Dopants are impurities intentionally introduced to

7965-504: The 3T and 4T DRAM which it replaced in the 1970s. In 1T DRAM cells, the bit of data is still stored in a capacitive region controlled by a transistor, but this capacitance is no longer provided by a separate capacitor. 1T DRAM is a "capacitorless" bit cell design that stores data using the parasitic body capacitance that is inherent to silicon on insulator (SOI) transistors. Considered a nuisance in logic design, this floating body effect can be used for data storage. This gives 1T DRAM cells

8100-464: The 3T1C cell for performance reasons (Kenner, p. 6). These performance advantages included, most significantly, the ability to read the state stored by the capacitor without discharging it, avoiding the need to write back what was read out (non-destructive read). A second performance advantage relates to the 3T1C cell's separate transistors for reading and writing; the memory controller can exploit this feature to perform atomic read-modify-writes, where

8235-462: The 64 Kbit generation, DRAM arrays have included spare rows and columns to improve yields. Spare rows and columns provide tolerance of minor fabrication defects which have caused a small number of rows or columns to be inoperable. The defective rows and columns are physically disconnected from the rest of the array by a triggering a programmable fuse or by cutting the wire by a laser. The spare rows or columns are substituted in by remapping logic in

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8370-507: The DDR3 memory does achieve 32 times higher bandwidth; due to internal pipelining and wide data paths, it can output two words every 1.25 ns (1 600  Mword/s) , while the EDO DRAM can output one word per t PC  = 20 ns (50 Mword/s). Each bit of data in a DRAM is stored as a positive or negative electrical charge in a capacitive structure. The structure providing

8505-475: The DRAM market is that there are currently only three major suppliers — Micron Technology , SK Hynix and Samsung Electronics " that are "keeping a pretty tight rein on their capacity". There is also Kioxia (previously Toshiba Memory Corporation after 2017 spin-off) which doesn't manufacture DRAM. Other manufacturers make and sell DIMMs (but not the DRAM chips in them), such as Kingston Technology , and some manufacturers that sell stacked DRAM (used e.g. in

8640-440: The DRAM to refresh or to provide a row address. Under some conditions, most of the data in DRAM can be recovered even if the DRAM has not been refreshed for several minutes. Many parameters are required to fully describe the timing of DRAM operation. Here are some examples for two timing grades of asynchronous DRAM, from a data sheet published in 1998: Thus, the generally quoted number is the /RAS low to valid data out time. This

8775-415: The Hawthorne site was smaller than its sister site at Yorktown Heights (with none of the wet lab space found in the Yorktown Heights facility). The primary focus at Hawthorne was software- and services-related research, whereas Yorktown Heights focuses on chemistry, mathematics, physics, silicon technology, and electrical engineering research, as well as some software and services. The building also contained

8910-557: The United States accused Japanese companies of export dumping for the purpose of driving makers in the United States out of the commodity memory chip business. Prices for the 64K product plummeted to as low as 35 cents apiece from $ 3.50 within 18 months, with disastrous financial consequences for some U.S. firms. On 4 December 1985 the US Commerce Department's International Trade Administration ruled in favor of

9045-479: The bitline, which is almost always made of polysilicon, but is otherwise identical to the COB variation. The advantage the COB variant possesses is the ease of fabricating the contact between the bitline and the access transistor's source as it is physically close to the substrate surface. However, this requires the active area to be laid out at a 45-degree angle when viewed from above, which makes it difficult to ensure that

9180-415: The bitline. Sense amplifiers are required to read the state contained in the DRAM cells. When the access transistor is activated, the electrical charge in the capacitor is shared with the bitline. The bitline's capacitance is much greater than that of the capacitor (approximately ten times). Thus, the change in bitline voltage is minute. Sense amplifiers are required to resolve the voltage differential into

9315-436: The bitlines are divided into multiple segments, and the differential sense amplifiers are placed in between bitline segments. Because the sense amplifiers are placed between bitline segments, to route their outputs outside the array, an additional layer of interconnect placed above those used to construct the wordlines and bitlines is required. The DRAM cells that are on the edges of the array do not have adjacent segments. Since

9450-417: The capacitance can be increased by etching a deeper hole without any increase to surface area (Kenner, p. 44). Another advantage of the trench capacitor is that its structure is under the layers of metal interconnect, allowing them to be more easily made planar, which enables it to be integrated in a logic-optimized process technology, which have many levels of interconnect above the substrate. The fact that

9585-406: The capacitance, as well as the transistors that control access to it, is collectively referred to as a DRAM cell . They are the fundamental building block in DRAM arrays. Multiple DRAM memory cell variants exist, but the most commonly used variant in modern DRAMs is the one-transistor, one-capacitor (1T1C) cell. The transistor is used to admit current into the capacitor during writes, and to discharge

9720-410: The capacitor contact does not touch the bitline. CUB cells avoid this, but suffer from difficulties in inserting contacts in between bitlines, since the size of features this close to the surface are at or near the minimum feature size of the process technology (Kenner, pp. 33–42). The trench capacitor is constructed by etching a deep hole into the silicon substrate. The substrate volume surrounding

9855-417: The capacitor during reads. The access transistor is designed to maximize drive strength and minimize transistor-transistor leakage (Kenner, p. 34). The capacitor has two terminals, one of which is connected to its access transistor, and the other to either ground or V CC /2. In modern DRAMs, the latter case is more common, since it allows faster operation. In modern DRAMs, a voltage of +V CC /2 across

9990-404: The capacitor is required to store a logic one; and a voltage of −V CC /2 across the capacitor is required to store a logic zero. The resultant charge is Q = ± V C C 2 ⋅ C {\textstyle Q=\pm {V_{CC} \over 2}\cdot C} , where Q is the charge in coulombs and C is the capacitance in farads . Reading or writing

10125-410: The capacitor is under the logic means that it is constructed before the transistors are. This allows high-temperature processes to fabricate the capacitors, which would otherwise degrade the logic transistors and their performance. This makes trench capacitors suitable for constructing embedded DRAM (eDRAM) (Jacob, p. 357). Disadvantages of trench capacitors are difficulties in reliably constructing

10260-426: The capacitor to the write bitline just as in the 1T1C cell, but there was a separate read wordline and read transistor which connected an amplifier transistor to the read bitline. By the second generation, the drive to reduce cost by fitting the same amount of bits in a smaller area led to the almost universal adoption of the 1T1C DRAM cell, although a couple of devices with 4 and 16 Kbit capacities continued to use

10395-404: The capacitor's structures within deep holes and in connecting the capacitor to the access transistor's drain terminal (Kenner, p. 44). First-generation DRAM ICs (those with capacities of 1 Kbit), such as the archetypical Intel 1103 , used a three-transistor, one-capacitor (3T1C) DRAM cell with separate read and write circuitry. The write wordline drove a write transistor which connected

10530-506: The characteristics of MOS technology, he found it was capable of building capacitors, and that storing a charge or no charge on the MOS capacitor could represent the 1 and 0 of a bit, while the MOS transistor could control writing the charge to the capacitor. This led to his development of the single-transistor MOS DRAM memory cell. He filed a patent in 1967, and was granted U.S. patent number 3,387,286 in 1968. MOS memory offered higher performance,

10665-528: The characters on it "were remembered in a dynamic store." The store used a large bank of capacitors, which were either charged or not, a charged capacitor representing cross (1) and an uncharged capacitor dot (0). Since the charge gradually leaked away, a periodic pulse was applied to top up those still charged (hence the term 'dynamic')". In November 1965, Toshiba introduced a bipolar dynamic RAM for its electronic calculator Toscal BC-1411. In 1966, Tomohisa Yoshimaru and Hiroshi Komikawa from Toshiba applied for

10800-435: The circuitry used to read/write them. Integrated circuit An integrated circuit ( IC ), also known as a microchip , computer chip , or simply chip , is a small electronic device made up of multiple interconnected electronic components such as transistors , resistors , and capacitors . These components are etched onto a small piece of semiconductor material, usually silicon . Integrated circuits are used in

10935-482: The column (the illustration to the right does not include this important detail). They are generally known as the + and − bit lines. A sense amplifier is essentially a pair of cross-connected inverters between the bit-lines. The first inverter is connected with input from the + bit-line and output to the − bit-line. The second inverter's input is from the − bit-line with output to the + bit-line. This results in positive feedback which stabilizes after one bit-line

11070-596: The commercialized Z-RAM from Innovative Silicon, the TTRAM from Renesas and the A-RAM from the UGR / CNRS consortium. DRAM cells are laid out in a regular rectangular, grid-like pattern to facilitate their control and access via wordlines and bitlines. The physical layout of the DRAM cells in an array is typically designed so that two adjacent DRAM cells in a column share a single bitline contact to reduce their area. DRAM cell area

11205-583: The complaint. Synchronous dynamic random-access memory (SDRAM) was developed by Samsung . The first commercial SDRAM chip was the Samsung KM48SL2000, which had a capacity of 16   Mb , and was introduced in 1992. The first commercial DDR SDRAM ( double data rate SDRAM) memory chip was Samsung's 64   Mb DDR SDRAM chip, released in 1998. Later, in 2001, Japanese DRAM makers accused Korean DRAM manufacturers of dumping. In 2002, US computer makers made claims of DRAM price fixing . DRAM

11340-479: The components of the electronic circuit are completely integrated". The first customer for the new invention was the US Air Force . Kilby won the 2000 Nobel Prize in physics for his part in the invention of the integrated circuit. However, Kilby's invention was not a true monolithic integrated circuit chip since it had external gold-wire connections, which would have made it difficult to mass-produce. Half

11475-491: The crescent, which also leads to the employee parking lots. A large overhang protrudes from the front entryway of the building, and faces the visitor parking lot. The building houses a library, an auditorium and a cafeteria. It was designed by the architect Eero Saarinen and built in 1956–1961. The original building named Mohansic, for the area, was in Yorktown Heights; this building is in Yorktown proper. The Mohansic building

11610-473: The desktop Datapoint 2200 were built from bipolar integrated circuits, either TTL or the even faster emitter-coupled logic (ECL). Nearly all modern IC chips are metal–oxide–semiconductor (MOS) integrated circuits, built from MOSFETs (metal–oxide–silicon field-effect transistors). The MOSFET invented at Bell Labs between 1955 and 1960, made it possible to build high-density integrated circuits . In contrast to bipolar transistors which required

11745-418: The die must pass through the material electrically connecting the die to the package, through the conductive traces (paths) in the package, through the leads connecting the package to the conductive traces on the printed circuit board . The materials and structures used in the path these electrical signals must travel have very different electrical properties, compared to those that travel to different parts of

11880-412: The differential sense amplifiers require identical capacitance and bitline lengths from both segments, dummy bitline segments are provided. The advantage of the open bitline array is a smaller array area, although this advantage is slightly diminished by the dummy bitline segments. The disadvantage that caused the near disappearance of this architecture is the inherent vulnerability to noise , which affects

12015-541: The diffusion of impurities into silicon. A precursor idea to the IC was to create small ceramic substrates (so-called micromodules ), each containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which seemed very promising in 1957, was proposed to the US Army by Jack Kilby and led to the short-lived Micromodule Program (similar to 1951's Project Tinkertoy). However, as

12150-651: The drum of the Atanasoff–Berry Computer , the Williams tube and the Selectron tube . In 1966, Dr. Robert Dennard invented modern DRAM architecture in which there's a single MOS transistor per capacitor, at the IBM Thomas J. Watson Research Center , while he was working on MOS memory and was trying to create an alternative to SRAM which required six MOS transistors for each bit of data. While examining

12285-537: The early 1970s to 10 nanometers in 2017 with a corresponding million-fold increase in transistors per unit area. As of 2016, typical chip areas range from a few square millimeters to around 600 mm , with up to 25 million transistors per mm . The expected shrinking of feature sizes and the needed progress in related areas was forecast for many years by the International Technology Roadmap for Semiconductors (ITRS). The final ITRS

12420-558: The effectiveness of the differential sense amplifiers. Since each bitline segment does not have any spatial relationship to the other, it is likely that noise would affect only one of the two bitline segments. The folded bitline array architecture routes bitlines in pairs throughout the array. The close proximity of the paired bitlines provide superior common-mode noise rejection characteristics over open bitline arrays. The folded bitline array architecture began appearing in DRAM ICs during

12555-541: The entire die rather than being confined to the die periphery. BGA devices have the advantage of not needing a dedicated socket but are much harder to replace in case of device failure. Intel transitioned away from PGA to land grid array (LGA) and BGA beginning in 2004, with the last PGA socket released in 2014 for mobile platforms. As of 2018 , AMD uses PGA packages on mainstream desktop processors, BGA packages on mobile processors, and high-end desktop and server microprocessors use LGA packages. Electrical signals leaving

12690-580: The equivalent of millions of gates and operate at frequencies up to 1 GHz . Analog ICs, such as sensors , power management circuits , and operational amplifiers (op-amps), process continuous signals , and perform analog functions such as amplification , active filtering , demodulation , and mixing . ICs can combine analog and digital circuits on a chip to create functions such as analog-to-digital converters and digital-to-analog converters . Such mixed-signal circuits offer smaller size and lower cost, but must account for signal interference. Prior to

12825-453: The fastest supercomputers on the exascale ), separately such as Viking Technology . Others sell such integrated into other products, such as Fujitsu into its CPUs, AMD in GPUs, and Nvidia , with HBM2 in some of their GPU chips. The cryptanalytic machine code-named Aquarius used at Bletchley Park during World War II incorporated a hard-wired dynamic memory. Paper tape was read and

12960-417: The forcing voltage is removed. During a write to a particular cell, all the columns in a row are sensed simultaneously just as during reading, so although only a single column's storage-cell capacitor charge is changed, the entire row is refreshed (written back in), as illustrated in the figure to the right. Typically, manufacturers specify that each row must be refreshed every 64 ms or less, as defined by

13095-696: The former Robert S. Lamb estate in Croton-on-Hudson, New York , with others in Yorktown Heights, and downtown Ossining. The new headquarters were finally located with a new lab in Yorktown Heights designed by architect Eero Saarinen completed in 1961, with the 115th Street site closing in 1970. IBM later donated the New York City buildings to Columbia University; they are now known as the Casa Hispanica and Watson Hall. The lab expanded to Hawthorne in 1984. Notable staff have included

13230-412: The foundry model, fabless companies (like Nvidia ) only design and sell ICs and outsource all manufacturing to pure play foundries such as TSMC . These foundries may offer IC design services. The earliest integrated circuits were packaged in ceramic flat packs , which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to

13365-510: The greatest density as well as allowing easier integration with high-performance logic circuits since they are constructed with the same SOI process technologies. Refreshing of cells remains necessary, but unlike with 1T1C DRAM, reads in 1T DRAM are non-destructive; the stored charge causes a detectable shift in the threshold voltage of the transistor. Performance-wise, access times are significantly better than capacitor-based DRAMs, but slightly worse than SRAM. There are several types of 1T DRAMs:

13500-399: The headquarters of IBM Research , situated on private land not generally accessible to the public, is a large crescent-shaped structure consisting of three levels with 40 aisles each, radiating out from the center of the circle described by the crescent. Due to this construction, none of the offices have windows. The lowest level is partially underground in some areas toward the shorter side of

13635-568: The highest-speed integrated circuits. It took decades to perfect methods of creating crystals with minimal defects in semiconducting materials' crystal structure . Semiconductor ICs are fabricated in a planar process which includes three key process steps – photolithography , deposition (such as chemical vapor deposition ), and etching . The main process steps are supplemented by doping and cleaning. More recent or high-performance ICs may instead use multi-gate FinFET or GAAFET transistors instead of planar ones, starting at

13770-488: The hole is then heavily doped to produce a buried n plate with low resistance. A layer of oxide-nitride-oxide dielectric is grown or deposited, and finally the hole is filled by depositing doped polysilicon, which forms the top plate of the capacitor. The top of the capacitor is connected to the access transistor's drain terminal via a polysilicon strap (Kenner, pp. 42–44). A trench capacitor's depth-to-width ratio in DRAMs of

13905-602: The idea to the public at the Symposium on Progress in Quality Electronic Components in Washington, D.C. , on 7 May 1952. He gave many symposia publicly to propagate his ideas and unsuccessfully attempted to build such a circuit in 1956. Between 1953 and 1957, Sidney Darlington and Yasuo Tarui ( Electrotechnical Laboratory ) proposed similar chip designs where several transistors could share

14040-421: The late 1990s, radios could not be fabricated in the same low-cost CMOS processes as microprocessors. But since 1998, radio chips have been developed using RF CMOS processes. Examples include Intel's DECT cordless phone, or 802.11 ( Wi-Fi ) chips created by Atheros and other companies. Modern electronic component distributors often further sub-categorize integrated circuits: The semiconductors of

14175-425: The lengths of the bitlines and the number of attached DRAM cells attached to them are equal, two basic architectures to array design have emerged to provide for the requirements of the sense amplifiers: open and folded bitline arrays. The first generation (1 Kbit) DRAM ICs, up until the 64 Kbit generation (and some 256 Kbit generation devices) had open bitline array architectures. In these architectures,

14310-471: The levels specified by the logic signaling system. Modern DRAMs use differential sense amplifiers, and are accompanied by requirements as to how the DRAM arrays are constructed. Differential sense amplifiers work by driving their outputs to opposing extremes based on the relative voltages on pairs of bitlines. The sense amplifiers function effectively and efficient only if the capacitance and voltages of these bitline pairs are closely matched. Besides ensuring that

14445-544: The list in the 06/2005 issue, then positioned second behind fellow Blue Gene/L in LLNL . Another well-known installation is Watson , an artificial intelligence system capable of answering natural language questions, which won several Jeopardy! games against human contestants in February 2011 on the site, and defeated Jeopardy! super-champions Ken Jennings and Brad Rutter . The Yorktown Heights building, housing

14580-726: The mathematicians Benoît Mandelbrot , Ralph E. Gomory , Shmuel Winograd , Alan Hoffman , Don Coppersmith , Gregory Chaitin , physicist and presidential advisor Richard Garwin , inventor Robert Dennard , roboticist Matthew T. Mason , author Clifford A. Pickover , computer scientists Frances E. Allen , John Cocke , Stuart Feldman , Ken Iverson , Irene Greif , and Mark N. Wegman , Barry Appelman , Wietse Venema , Harry Markowitz (Economics Nobel Prize, 1990), electrical engineer Jeffrey Kephart , and physicists Llewellyn Thomas , Rolf Landauer , Charles H. Bennett , Elliott H. Lieb , J. B. Gunn , Leroy Chang , Leo Esaki (Physics Nobel Prize, 1973), Jay Gambetta , Uri Sivan (president of

14715-620: The mathematics and science that support the information technology industry. The center was founded at Columbia University in 1945 as the Watson Scientific Computing Laboratory, on 116th Street in Manhattan , expanding to 115th Street in 1953. More labs were later opened in Westchester County, New York beginning in the late 1950s with the temporary facility and research headquarters at

14850-402: The mid-1980s, beginning with the 256 Kbit generation. This architecture is favored in modern DRAM ICs for its superior noise immunity. This architecture is referred to as folded because it takes its basis from the open array architecture from the perspective of the circuit schematic. The folded array architecture appears to remove DRAM cells in alternate pairs (because two DRAM cells share

14985-407: The mid-2000s can exceed 50:1 (Jacob, p. 357). Trench capacitors have numerous advantages. Since the capacitor is buried in the bulk of the substrate instead of lying on its surface, the area it occupies can be minimized to what is required to connect it to the access transistor's drain terminal without decreasing the capacitor's size, and thus capacitance (Jacob, pp. 356–357). Alternatively,

15120-433: The number of MOS transistors in an integrated circuit to double every two years, a trend known as Moore's law. Moore originally stated it would double every year, but he went on to change the claim to every two years in 1975. This increased capacity has been used to decrease cost and increase functionality. In general, as the feature size shrinks, almost every aspect of an IC's operation improves. The cost per transistor and

15255-450: The performance of different DRAM memories, as it sets the slower limit regardless of the row length or page size. Bigger arrays forcibly result in larger bit line capacitance and longer propagation delays, which cause this time to increase as the sense amplifier settling time is dependent on both the capacitance as well as the propagation latency. This is countered in modern DRAM chips by instead integrating many more complete DRAM arrays within

15390-497: The project was gaining momentum, Kilby came up with a new, revolutionary design: the IC. Newly employed by Texas Instruments , Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working example of an integrated circuit on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material … wherein all

15525-592: The purposes of construction and commerce. In strict usage, integrated circuit refers to the single-piece circuit construction originally known as a monolithic integrated circuit , which comprises a single piece of silicon. In general usage, circuits not meeting this strict definition are sometimes referred to as ICs, which are constructed using many different technologies, e.g. 3D IC , 2.5D IC , MCM , thin-film transistors , thick-film technologies , or hybrid integrated circuits . The choice of terminology frequently appears in discussions related to whether Moore's Law

15660-422: The row and column decoders (Jacob, pp. 358–361). Electrical or magnetic interference inside a computer system can cause a single bit of DRAM to spontaneously flip to the opposite state. The majority of one-off (" soft ") errors in DRAM chips occur as a result of background radiation , chiefly neutrons from cosmic ray secondaries, which may change the contents of one or more memory cells or interfere with

15795-399: The same address pins to receive the low half and the high half of the address of the memory cell being referenced, switching between the two halves on alternating bus cycles. This was a radical advance, effectively halving the number of address lines required, which enabled it to fit into packages with fewer pins, a cost advantage that grew with every jump in memory size. The MK4096 proved to be

15930-614: The same die. As a result, they require special design techniques to ensure the signals are not corrupted, and much more electric power than signals confined to the die itself. IBM Thomas J. Watson Research Center The Thomas J. Watson Research Center is the headquarters for IBM Research . Its main laboratory is in Yorktown Heights, New York , 38 miles (61 km) north of New York City . It also operates facilities in Cambridge, Massachusetts and Albany, New York . The center, headquarters of IBM 's Research division ,

16065-449: The same size – a modern chip may have many billions of transistors in an area the size of a human fingernail. These advances, roughly following Moore's law , make the computer chips of today possess millions of times the capacity and thousands of times the speed of the computer chips of the early 1970s. ICs have three main advantages over circuits constructed out of discrete components: size, cost and performance. The size and cost

16200-462: The site is the main facility of IBM Research's Semiconductor Group . The group focuses on next generation semiconductor technology research, and is the group most associated with a number of innovations related to semiconductor scaling, including the introduction of a 7 nm test chip in 2015, a 5 nm test chip in 2017. and a 2 nm test chip in 2021. This group operates an advanced extreme ultraviolet lithography enabled research line which

16335-474: The size of the transistors. Such techniques are collectively known as advanced packaging . Advanced packaging is mainly divided into 2.5D and 3D packaging. 2.5D describes approaches such as multi-chip modules while 3D describes approaches where dies are stacked in one way or another, such as package on package and high bandwidth memory. All approaches involve 2 or more dies in a single package. Alternatively, approaches such as 3D NAND stack multiple layers on

16470-399: The stacked capacitor, based on its location relative to the bitline—capacitor-under-bitline (CUB) and capacitor-over-bitline (COB). In the former, the capacitor is underneath the bitline, which is usually made of metal, and the bitline has a polysilicon contact that extends downwards to connect it to the access transistor's source terminal. In the latter, the capacitor is constructed above

16605-468: The structural simplicity of DRAM memory cells: only one transistor and a capacitor are required per bit, compared to four or six transistors in SRAM. This allows DRAM to reach very high densities with a simultaneous reduction in cost per bit. Refreshing the data consumes power, causing a variety of techniques to be used to manage the overall power consumption. For this reason, DRAM usually needs to operate with

16740-445: The structure of modern societies, made possible by the small size and low cost of ICs such as modern computer processors and microcontrollers . Very-large-scale integration was made practical by technological advancements in semiconductor device fabrication . Since their origins in the 1960s, the size, speed, and capacity of chips have progressed enormously, driven by technical advances that fit more and more transistors on chips of

16875-462: The substrate surface are referred to as trench capacitors. In the 2000s, manufacturers were sharply divided by the type of capacitor used in their DRAMs and the relative cost and long-term scalability of both designs have been the subject of extensive debate. The majority of DRAMs, from major manufactures such as Hynix , Micron Technology , Samsung Electronics use the stacked capacitor structure, whereas smaller manufacturers such Nanya Technology use

17010-453: The trench capacitor structure (Jacob, pp. 355–357). The capacitor in the stacked capacitor scheme is constructed above the surface of the substrate. The capacitor is constructed from an oxide-nitride-oxide (ONO) dielectric sandwiched in between two layers of polysilicon plates (the top plate is shared by all DRAM cells in an IC), and its shape can be a rectangle, a cylinder, or some other more complex shape. There are two basic variations of

17145-482: The wordline, is connected to the gate terminal of every access transistor in its row. The vertical bitline is connected to the source terminal of the transistors in its column. The lengths of the wordlines and bitlines are limited. The wordline length is limited by the desired performance of the array, since propagation time of the signal that must transverse the wordline is determined by the RC time constant . The bitline length

17280-401: Was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962. General Microelectronics later introduced the first commercial MOS integrated circuit in 1964, a 120-transistor shift register developed by Robert Norman. By 1964, MOS chips had reached higher transistor density and lower manufacturing costs than bipolar chips. MOS chips further increased in complexity at

17415-439: Was cheaper, and consumed less power, than magnetic-core memory. The patent describes the invention: "Each cell is formed, in one embodiment, using a single field-effect transistor and a single capacitor." MOS DRAM chips were commercialized in 1969 by Advanced Memory Systems, Inc of Sunnyvale, CA . This 1024 bit chip was sold to Honeywell , Raytheon , Wang Laboratories , and others. The same year, Honeywell asked Intel to make

17550-441: Was developed at Fairchild Semiconductor by Federico Faggin in 1968. The application of MOS LSI chips to computing was the basis for the first microprocessors , as engineers began recognizing that a complete computer processor could be contained on a single MOS LSI chip. This led to the inventions of the microprocessor and the microcontroller by the early 1970s. During the early 1970s, MOS integrated circuit technology enabled

17685-431: Was generally described as "5-2-2-2" timing, as bursts of four reads within a page were common. When describing synchronous memory, timing is described by clock cycle counts separated by hyphens. These numbers represent t CL - t RCD - t RP - t RAS in multiples of the DRAM clock cycle time. Note that this is half of the data transfer rate when double data rate signaling is used. JEDEC standard PC3200 timing

17820-514: Was issued in 2016, and it is being replaced by the International Roadmap for Devices and Systems . Initially, ICs were strictly electronic devices. The success of ICs has led to the integration of other technologies, in an attempt to obtain the same advantages of small size and low cost. These technologies include mechanical devices, optics, and sensors. As of 2018 , the vast majority of all transistors are MOSFETs fabricated in

17955-477: Was strongly motivated by economics, a major consideration for DRAM devices, especially commodity DRAMs. The minimization of DRAM cell area can produce a denser device and lower the cost per bit of storage. Starting in the mid-1980s, the capacitor was moved above or below the silicon substrate in order to meet these objectives. DRAM cells featuring capacitors above the substrate are referred to as stacked or folded plate capacitors. Those with capacitors buried beneath

18090-480: Was the largest single consumer of integrated circuits between 1961 and 1965. Transistor–transistor logic (TTL) was developed by James L. Buie in the early 1960s at TRW Inc. TTL became the dominant integrated circuit technology during the 1970s to early 1980s. Dozens of TTL integrated circuits were a standard method of construction for the processors of minicomputers and mainframe computers . Computers such as IBM 360 mainframes, PDP-11 minicomputers and

18225-576: Was the temporary area for Research while the TJ Watson building was being constructed. The facility can be found at 257 Fuller Rd, Albany, New York; it is located in facilities owned by the State University of New York's Polytechnic Institute's Colleges of Nanoscale Science and Engineering (SUNY-CNSE) which also hosts the Center for Semiconductor Research (CSR). The IBM occupied portion of

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