Integrated Circuits

3.386157517854 (2095)
Posted by motoman 03/12/2009 @ 14:07

Tags : integrated circuits, semi conductors, technology

News headlines
Contract Awarded to Teledyne Scientific - San Fernando Valley Business Journal Online
A subsidiary of Teledyne Technologies Inc. received an $8 million to develop electronics devices and integrated circuits over the next two years. The circuits and devices developed by Teledyne Scientific & Imaging will be used in Department of Defense...
Advanced 555 Timer Integrated Circuit - Ultra-Low Power & Programmable - Business Wire (press release)
CustomSiliconSolutions.com), a leading fabless semiconductor company that provides turn-key ASIC (Application Specific Integrated Circuit) and standard product solutions to its customers, is announcing the availability of the CSS555C integrated circuit...
Graphene May Have Advantages Over Copper For IC Interconnects At ... - Science Daily (press release)
Researchers have now experimentally demonstrated the potential for another graphene application: replacing copper for interconnects in future generations of integrated circuits. In a paper published in the June 2009 issue of the IEEE journal Electron...
RFaxis Launches Industry's First RF Front-End Integrated Circuits - SYS-CON Media (press release)
The RFX2401 is the first and only fully integrated, single-chip, single-die Bluetooth/Zigbee RFeIC (RF Front-end Integrated Circuit) on the market. The chip's architecture integrates the PA, LNA, transmit and receive switching circuitry, the associated...
Microsemi Introduces Next Generation LED Chipset Solution for LED ... - GlobeNewsWire (press release)
Microsemi Corporation, with corporate headquarters in Irvine, California, is a leading designer, manufacturer and marketer of high performance analog and mixed-signal integrated circuits and high reliability semiconductors. The company's semiconductors...
[Feature] Expanded Use of Silicon Tuners Transforms TVs - Tech-On English
With analog television broadcasting slated for the axe in about two years in Japan, TV broadcast tuners are evolving rapidly, replacing old radio frequency (RF) analog circuits with new integrated circuits (IC) called silicon tuners....
Making Sense of Change - Rapid Growth
Enthusiasm just bubbles from the Lapeer, Mich. native as he discusses flexible substrates, organic-based transistors, vacuum sputtering and integrated circuits -- all in the context of solutions meant to conquer a problem. It's obvious that he revels...
Microsemi to Present At the UBS Global Technology and Services ... - GlobeNewsWire (press release)
Microsemi Corporation, with corporate headquarters in Irvine, California, is a leading designer, manufacturer and marketer of high performance analog and mixed-signal integrated circuits and high reliability semiconductors. The company's semiconductors...
Graphene to Replace Copper at the Nanoscale - Softpedia
They add that the new material is able to out-perform copper at what it does best, and namely connect transistors and other electrical devices in integrated circuits. Also, the new technology may have the potential to boost the overall processing power...
Atotech & SEMATECH partner on Process Solutions for 3D Integrated ... - evertiq.se
... the program began addressing the infrastructure and development challenges in 3D-TSV, including materials characterization, unit processes and integration, equipment hardening, reliability, cost and benefit to device and circuit performance....

Heat generation in integrated circuits

Joule Heating is a predominant heat mechanism for heat generation in integrated circuits and is an undesired effect.

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Readout integrated circuits

Readout integrated circuit (ROIC) is an electrical circuit multiplexer that mechanically and electrically interfaces or couples to a focal plane array (FPA) sensor/detector serving to function as a voltage buffer which measures or reads individual FPA outputs (sensor data or information) that are driven by incident electromagnetic energy on each and every individual input FPA unit cell or detector and transforms or transmits the sensor data to external electronics. The main function of an infrared readout circuit is to transform a very small diode incremental current, generated by infrared radiation, into a relatively large measurable output voltage. This is commonly done by integrating the photocurrent in a small capacitor during a fixed period of time. The capacitor’s voltage at the end of the integration period should be proportional to the current and as such to the incident infrared radiation of a pixel corresponding to the location of the infrared diode photo sensor. Infrared imagers consist of linear or two dimensional arrays including a very large number of infrared photo sensors. These arrays are denoted linear or focal plane arrays. Given that in the most general case each pixel of an image requires an individual readout circuit, the electronics associated to an infrared imager consists of a very large number (thousands) of readout circuits. Readout electronics are implemented as very large scale application specific integrated circuits or ASIC in CMOS technology. Due to the fact that infrared imagers can have several thousand unit cells, the unit cell is required to be very compact, to have very low power dissipation and at the same time to have high performance characteristics.

A typical FPA may be composed of 512 columns by 512 rows of individual (assuming no crosstalk) unit cells or pixels having a physical size of 30um by 30 um which define the image frame of the electromagnetic energy incident on the surface. The function of the ROIC is to scan the 512 by 512 array, not unlike a raster scan, in such a way as to sychronously read and bring together in a formatted way all the pixel outputs from the FPA into an appropriate lower impedance electrical circuit for video transmission and processing. Each unit cell detector output responds (gain) to a limited range of wavelengths of the electromagnetic energy incident upon the input, thereby defining the image as infrared, visible, x-ray, etc. The ROIC inputs are composed of a source follower FET topology (voltage buffer) such as to transform large unit cell output impedance to low input impedance to drive a transmission via (several hundreds of pF) of the unit cell output response. Each unit cell is given a fixed amount of time (integration time) to sample the incident electromagnetic energy before being readout, not unlike a sample and hold circuit.

The interface of the readout to the array is composed of hybridized indium dots for each and every unit cell-to-source follower interface. For example, GaN detector arrays are hybridized to a Si ROIC using flip chip bonding technology. An example of a ROIC is Raytheon's CRC-774, 320 by 240 matrix.

Scanning the array can be done in various ways. Several methods exist, including: snapshot; fowler; sampling up the ramp. Integration and readout modes include integrate-while-read and integrate-then-read.

The opposite use of a readout IC (ROIC) is the readin IC (RIIC) which is used to produce or simulate images in a focal plane array. The analogous image system using a RIIC for image simulation is the television image process. Image simulation is used for hardware-in-the-loop (HIL) testing purposes.

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Integrated circuit packaging

Early USSR made integrated circuit

Integrated circuit packaging is the final stage of semiconductor device fabrication per se, followed by IC testing.

In the integrated circuit industry it is called simply packaging and sometimes semiconductor device assembly, or simply assembly. Also, sometimes it is called encapsulation or seal, by the name of its last step, which might lead to confusion, because the term packaging generally comprises the steps or the technology of mounting and interconnecting of devices (see Chip carrier, Category:Chip carriers).

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 the dual in-line package (DIP), first in ceramic and later in plastic. 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 small-outline integrated circuit — a carrier which occupies an area about 30 – 50% less than an equivalent DIP, with a typical thickness that is 70% less. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches.

Small-outline integrated circuit (SOIC) and Plastic leaded chip carrier (PLCC) packages. In the late 1990s, plastic quad flat pack (PQFP) and thin small-outline packages (TSOP) became the most common for high pin count devices, though PGA packages are still often used for high-end microprocessors. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to land grid array (LGA) packages.

Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball Grid Array packages, which allow for 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 the entire die rather than being confined to the die periphery.

Traces out of the die, through the package, and into the printed circuit board have very different electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself.

When multiple dies are stacked in one package, it is called SiP, for System In Package, or three-dimensional integrated circuit. When multiple dies are combined on a small substrate, often ceramic, it's called an MCM, or Multi-Chip Module. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy.

The following operations are performed at this stage.

The vast majority of integrated circuits are packaged in opaque ceramic or plastic insulation. The only connection to the outside world is through metal pins (sometimes called "leads") through the insulation.

The rare exceptions include proximity communication ; "blob on PCB" that attaches the raw die directly to a PCB, bonds the die wires directly to the PCB traces, then covers the die and the die wires with a blob of insulator; and partially or totally transparent packaging for optical input and/or output of optoelectronic devices and EPROM.

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Dual in-line package

Side view of a dual in-line package (DIP) IC.

In microelectronics, a dual in-line package (DIP), sometimes called a DIL package, is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The pins are all parallel, point downward, and extend past the bottom plane of the package at least enough to be through-hole mounted to a printed circuit board (PCB), i.e. to pass through holes on the PCB and be soldered on the other side. DIP is also sometimes considered to stand for dual in-line pin, in which case the phrase "DIP package" is non-redundant. Generally, a DIP is relatively broadly defined as any rectangular package with two uniformly spaced parallel rows of pins pointing downward, whether it contains an IC chip or some other device(s), and whether the pins emerge from the sides of the package and bend downwards or emerge directly from the bottom of the package and are completely straight. In more specific usage, the term refers only an IC package of the former description (with bent leads at the sides.) A DIP is usually referred to as a DIPn, where n is the total number of pins. For example, a microcircuit package with two rows of seven vertical leads would be a DIP14. The photograph at the upper right shows three DIP14 ICs.

DIPs may be used for semiconductor integrated circuits (ICs, "chips"), like logic gates, analog circuits, and microprocessors, which is by far their most common use. They may also be used for other types of devices including arrays of discrete components such as resistors (often called resistor packs), arrays of miniature rocker or slide switches known as DIP switches, various LED arrays including segmented and bargraph displays and light bars, miniature rotary encoder switches, and electromechanical relays. Integrated circuits and resistor arrays usually have bent leads which extend from the sides of the package and turn to point downward; the IC packages tend to be black, and DIP resistor networks tend to be dark yellow or white plastic. The other types of DIP components, particularly LED devices, usually have completely straight pins (leads) extending directly from the bottom/back of the package, which is usually molded plastic and can be any color.

DIP plugs for ribbon cable, to connect to DIP sockets, have also been made (and can be found in some Apple II computers, as well as on some electronics test equipment used by technicians.) Dallas Semiconductor manufactured integrated DIP real-time clock (RTC) modules which contained an IC chip and a non-replaceable 10-year lithium battery. Both of these were examples of devices with pins emerging from the bottom; the construction of the RTC modules was very similar to the LED displays described below, with epoxy in a plastic shell. The RTC modules are an example of a component that could not be easily converted to surface-mount, as their size and weight with the contained battery would push the limits of mechanical strength of surface solder pads, and the thicker leads of a DIP as compared to most SMT packages were probably necessary to mechanically support the battery. Dallas also sold the same RTC chips without a battery in standard side-lead DIP packages; both versions would physically fit the same DIP sockets.

Some older equipment (circa the 1970s) used DIP terminal blocks onto the top of which discrete components could be soldered; these blocks (typically DIP16 size) would then be plugged into sockets on circuit boards and could be easily removed and swapped out, or test equipment connected between them and their sockets, for repair or testing of the machines they were a part of. These saw use mainly in industrial, commercial, and prototype equipment, not consumer electronics.

Dual in-line packages were invented at Fairchild in 1965 and, by allowing integrated circuits to be packaged more densely than previous round packages did, made it possible to build complex systems such as sophisticated computers. The package was well-suited to automated assembly equipment; a printed circuit board could be populated with scores or hundreds of ICs, then have all devices soldered at once (e.g. on a wave soldering machine) and passed on to automated testing machines, with very little human labor required. However, the packages were still large with respect to the integrated circuits within them. By the end of the 20th century, most ICs were packaged in surface-mount packages, which allowed further reduction in the size and weight of systems. DIP chips are still popular for circuit prototyping on a breadboard because of how easily they can be inserted and utilized there.

For programmable devices like EPROMs and GALs, DIPs remained popular for many years due to their easy handling with external programming circuitry (i.e., the DIP devices could be simply plugged into a socket on the programming device.) However, with In-System Programming (ISP) technology now state of the art, this advantage of DIPs is rapidly losing importance as well. Through the 1990s, devices with pin counts below 20 were manufactured in a DIP format in addition to the newer formats. Since about 2000, newer devices are often unavailable in the DIP format, though many still are.

DIPs can be mounted on a circuit board either directly using through-hole soldering or using inexpensive spring-contact sockets. Using a DIP socket allows for easy replacement of a device and eliminates the risk of damage from overheating during soldering (as the device is inserted into the soldered socket only after it has cooled.) These are by far the most common mounting types for DIP components. DIPs can also be easily and conveniently used with standard protoboards/breadboards, whose design includes extensive consideration for them; this is a temporary mounting arrangement for circuit design development or device testing. Some hobbyists, for one-off construction or permanent prototyping, use point-to-point wiring with DIPs, and their appearance when physically inverted as part of this method inspires the informal term "dead bug style" for the method.

The body (housing) of a DIP containing an IC chip is usually made from molded plastic or ceramic in two halves, an upper and a lower half, joined and sealed at a seam. The pins emerge from the longer sides of the package along the seam, parallel to the top and bottom planes of the package, and are bent downward approximately 90 degrees (or slightly less, leaving them angled slightly outward from the centerline of the package body.) (The SOIC, the SMT package that most resembles a typical DIP, appears essentially the same, notwithstanding size scale, except that after being bent down the pins are bent upward again by an equal angle to become parallel with the bottom plane of the package.) In ceramic (CERDIP) packages, an epoxy or grout is used to hermetically seal the two halves together, providing an air and moisture tight seal to protect the IC die inside. Plastic DIP (PDIP) packages are usually sealed by fusing or cementing the plastic halves around the leads, but a high degree of hermeticity is not achieved because the plastic itself is usually somewhat porous to moisture and the process cannot ensure a good microscopic seal between the leads and the plastic at all points around the perimeter. However, contaminants are usually still kept out well enough that the device can operate reliably for decades with reasonable care in a controlled environment.

Also, a large DIP package (such as the DIP64 used for the Motorola 68000 CPU) incorporates substantial lead length inside the package between the pins located toward the ends of the package and the chip die at its center, making such a package unsuitable for high-speed microarchitectures (above a few hundred megahertz), which require lead length to be kept to a minimum. The 68000 ran at no more than 20 MHz, so this was not an issue for it.

Some other types of DIP devices are built very differently. Most of these have molded plastic housings and straight pins or leads that extend directly out of the bottom of the package. For some, LED displays particularly, the housing is usually a hollow plastic box with the bottom/back open, filled (around the contained electronic components) with a hard translucent epoxy material from which the leads emerge. Others, such as DIP switches, are composed of two (or more) plastic housing parts snapped, welded, or glued together around a set of contacts and tiny mechanical parts, with the leads emerging through molded-in holes or notches in the plastic.

For EPROMs, which can be erased by UV light, some DIPs, generally ceramic CERDIPs, were manufactured with a circular window of clear quartz in the center of the top of the package, over the chip die. This enabled the packaged chips to be erased by UV irradiation in an EPROM eraser. Often, the same chips were also sold in less expensive windowless PDIP or CERDIP packages as one-time programmable (OTP) versions. (These were actually the same erasable chips, but there was no way to get UV radiation to them to erase them.) The same windowed and windowless packages were also used for microcontrollers, and perhaps other devices, containing EPROM memory; in this context, the OTP nature of the windowless versions was sometimes a needed requirement of the customer (i.e., to prevent their end users from modifying the stored information, which might include access control bits to disable read-out of proprietary code or factory test modes which were disabled after final test qualification.) Windowed CERDIP-packaged PROMs were used for the BIOS ROM of many early IBM PC clones (which were manufactured in limited enough quantities to make PROM an economical choice) often with a foil-backed (or regular paper) adhesive label covering the window to prevent inadvertent erasure through exposure to ambient light.

The most common DIPs have an inter-lead spacing (lead pitch) of 0.1 in. (2.54 mm) and a row spacing of either 0.3 in. (7.62 mm) or 0.6 in. (15.24 mm). In some contexts, the term DIP, especially PDIP or CERDIP, implies this spacing. The number of pins is always even; typical pin counts are 8 or from 14 to 24 (and, less commonly, 28) for 0.3 in. packages, and 24, 28, 32 or 40 (less commonly, 36, 48 or 52) for 0.6 in packages. Some 4-pin DIPs exist, e.g. containing optoisolators. Where there is a need to differentiate between the two widths for the same pin count, the term "Skinny DIP" is informally used to refer to the 0.3 in version. JEDEC standards also specify less common packages with a row spacing of 0.4 in (10.16 mm), or 0.9 in (22.86 mm) with a pin-count of up to 64. Other standardized variants include a denser lead pitch of 0.07 in (1.778 mm) at a row spacing of 0.3 in, 0.6 in or 0.75 in. The former Soviet Union and Eastern bloc countries used similar packages, but with a metric inter-lead spacing of 2.5 mm rather than 2.54 mm (0.1 in).

The Motorola 68000 CPU (MC68000) was perhaps the largest common DIP IC; it was packaged in a PDIP with 64 pins on 0.1 in. centers. The MC68000 can be found in this form in the original Apple Macintosh line, early HP LaserJet-series printers, and the original, wider Sega Genesis/Megadrive game console (where the 68000 takes up as much PCB space as the two surface-mount custom Sega VLSI ASICs combined.) Motorola also used this DIP package size for some other, less popular chips, such as the MC68451 MMU.

When a DIP is viewed from the top with the in-line pin rows horizontal, the pins are sequentially numbered counterclockwise, with pin numbers increasing from left to right across the bottom edge and from right to left across the top edge. Finding any given pin is simply a matter of finding pin 1 and then counting counterclockwise. Because the dual-inline pin arrangement has radial symmetry, the layout looks the same if the package is rotated 180 degrees; therefore, to resolve this ambiguity, one end of every DIP is marked with an orientation notch, a dot, or both. The notch is centered between the pin rows and may extend all the way through the end of the package or may be just cut into the top of the end, but it is almost always present. The dot will be on top of the corner of the package at the same end as the notch, if both are present, and it will usually be a molded depression, though it may be raised or even, rarely (except for ceramic packages), merely a printed mark. When the package is viewed from the top side, pin 1 is the pin at the corner with the dot, or it is the pin counterclockwise from the notch. (That is, counterclockwise around the center of the package.) Pin 1 is always in the same inline row as pin 2.

Merely knowing that pin 1 is a corner pin on the notched or dotted end, that pins 1 and 2 are always adjacent in the same inline row of pins, and that the pin numbering is always counterclockwise is sufficient to figure out the numbers of all the pins for any DIP package. Another way to remember the numbering, also sufficient for all DIPs, is that pin 1 and the highest numbered pin are the two corner pins at the notched and/or dotted end, and that the pin numbering is counterclockwise. By either of these rule sets, if pin 1 is misidentified at the wrong corner of the marked end, it is impossible to number the pins counterclockwise with increasing numbers.

Using basic math and logic, it can be concluded that for a package with any number of pins n (where n is always even, of course), if pin 1 is at the lower left corner (which implies that the pin rows are horizontal), then the bottom row is numbered 1 to n / 2 from left to right, and the top row is numbered n / 2 + 1 to n from right to left. So, for example, for a 14-pin DIP, n = 14 and n / 2 = 7; with the notch at the left, the bottom row pins are numbered from 1 to 7 (left to right) and the top row pins are numbered 8 to 14 (right to left). The diagram at the right above shows the DIP package rotated 90 degrees clockwise relative to this description (with pin 1 at the upper left instead of the lower left and the lines of pins vertical columns instead of horizontal rows), so the left column is numbered 1 to n / 2 from top to bottom, and the right column is numbered n / 2 + 1 to n from bottom to top.

Some DIP devices, such as segmented LED displays, have some pin position skipped (i.e. pins omitted there.) In that case, often the existing pins will still be numbered according to the corresponding positions on a standard DIP that has no gaps in the pin rows, so the numbers of the present pins will not be contiguous. This makes it easier for experienced engineers and technicians to identify pins on these devices using their knowledge of DIP pin numbering, though it may be initially confusing for amateur hobbyists, who may expect the physical pins of every device to be numbered sequentially. This highlights an important point: when naming a package according to the number of pins, e.g. DIP14, the number should be chosen not according to the number of actual pins but according to the number of pin positions on the package, or, in other words, according to the size of the standard DIP socket that the package will fit into. So, a 7-segment LED display with ten pins arranged in two rows 7 x 0.1 in. long and 0.3 in. apart (which leaves two missing-pin spaces on each side) would fit a DIP14 socket, but not a DIP12 or DIP10 socket, and therefore it should be identified as a DIP14; it has ten pins but 14 pin positions.

In addition to providing for human visual identification of the orientation of the package, the notch allows automated chip-insertion machinery to ensure correct orientation of the chip by mechanical sensing. A physical notch is also more durable than a printed mark, as it cannot wear off or fade, and, no less, it gains this benefit at a small savings of some material.

The SOIC (Small Outline IC), a surface-mount package which is currently very popular (in 2009), particularly in consumer electronics and personal computers, is essentially a shrunk version of the standard IC PDIP, the fundamental difference which makes it an SMT device being a second bend in the leads to flatten them parallel to the bottom plane of the plastic housing. The SOJ (Small Outline J-lead) and other SMT packages with "SOP" (for "Small Outline Package") in their names can be considered further relatives of the DIP, their original ancestor.

Pin grid array (PGA) packages may be considered to have evolved from the DIP. PGAs with the same 0.1 inch pin centers as most DIPs were popular for microprocessors from the early-mid 1980s through the 1990s. Owners of personal computers containing Intel 80286 through Pentium processors may be most familiar with these PGA packages, which were often inserted into ZIF sockets on motherboards. The similarity is such that a PGA socket may be physically compatible with some DIP devices, though the converse is not true.

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Application-specific integrated circuit

An application-specific integrated circuit (ASIC) is an integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC. Intermediate between ASICs and industry standard integrated circuits, like the 7400 or the 4000 series, are application specific standard products (ASSPs).

As feature sizes have shrunk and design tools improved over the years, the maximum complexity (and hence functionality) possible in an ASIC has grown from 5,000 gates to over 100 million. Modern ASICs often include entire 32-bit processors, memory blocks including ROM, RAM, EEPROM, Flash and other large building blocks. Such an ASIC is often termed a SoC (System-on-a-chip). Designers of digital ASICs use a hardware description language (HDL), such as Verilog or VHDL, to describe the functionality of ASICs.

Field-programmable gate arrays (FPGA) are the modern-day technology for building a breadboard or prototype from standard parts; programmable logic blocks and programmable interconnects allow the same FPGA to be used in many different applications. For smaller designs and/or lower production volumes, FPGAs may be more cost effective than an ASIC design even in production. The non-recurring engineering cost of an ASIC can run into the millions of dollars.

The initial ASICs used gate array technology. Ferranti produced perhaps the first gate-array, the ULA (Uncommitted Logic Array), around 1980. An early successful commercial application was the ULA circuitry found in the 8-bit ZX81 and ZX Spectrum low-end personal computers, introduced in 1981 and 1982. These were used by Sinclair Research (UK) essentially as a low-cost I/O solution aimed at handling the computer's graphics. Some versions of ZX81/Timex Sinclair 1000 used just four chips (ULA, 2Kx8 RAM, 8Kx8 ROM, Z80A CPU) to implement an entire mass-market personal computer with built-in BASIC interpreter.

Customization occurred by varying the metal interconnect mask. ULAs had complexities of up to a few thousand gates. Later versions became more generalized, with different base dies customised by both metal and polysilicon layers. Some base dies include RAM elements.

In the mid 1980s a designer would choose an ASIC manufacturer and implement their design using the design tools available from the manufacturer. While third party design tools were available, there was not an effective link from the third party design tools to the layout and actual semiconductor process performance characteristics of the various ASIC manufacturers. Most designers ended up using factory specific tools to complete the implementation of their designs. A solution to this problem that also yielded a much higher density device was the implementation of Standard Cells. Every ASIC manufacturer could create functional blocks with known electrical characteristics, such as propagation delay, capacitance and inductance, that could also be represented in third party tools. Standard Cell design is the utilization of these functional blocks to achieve very high gate density and good electrical performance. Standard cell design fits between Gate Array and Full Custom design in terms of both its NRE (Non-Recurring Engineering) and recurring component cost.

By the late 1990s, logic synthesis tools became available. Such tools could compile HDL descriptions into a gate-level netlist. This enabled a style of design called standard-cell design. Standard-cell Integrated Circuits (ICs) are designed in the following conceptual stages, although these stages overlap significantly in practice.

These steps, implemented with a level of skill common in the industry, almost always produce a final device that correctly implements the original design, unless flaws are later introduced by the physical fabrication process.

These design steps (or flow) are also common to standard product design. The significant difference is that Standard Cell design uses the manufacturer's cell libraries that have been used in potentially hundreds of other design implementations and therefore are of much lower risk than full custom design. Standard Cells produce a design density that is cost effective, and they can also integrate IP cores and SRAM (Static Random Access Memory) effectively, unlike Gate Arrays.

Gate array design is a manufacturing method in which the diffused layers, i.e. transistors and other active devices, are predefined and wafers containing such devices are held in stock prior to metallization, in other words, unconnected. The physical design process then defines the interconnections of the final device. For most ASIC manufacturers, this consists of from two to as many as five metal layers, each metal layer running parallel to the one below it. Non-recurring engineering costs are much lower as photo-lithographic masks are required only for the metal layers, and production cycles are much shorter as metallization is a comparatively quick process.

Gate array ASICs are always a compromise as mapping a given design onto what a manufacturer held as a stock wafer never gives 100% utilization. Often difficulties in routing the interconnect require migration onto a larger array device with consequent increase in the piece part price. These difficulties are often a result of the layout software used to develop the interconnect.

Pure, logic-only gate array design is rarely implemented by circuit designers today, replaced almost entirely by field-programmable devices, such as field-programmable gate arrays (FPGAs), which can be programmed by the user and thus offer minimal tooling charges (non-recurring engineering (NRE)), marginally increased piece part cost and comparable performance. Today gate arrays are evolving into structured ASICs that consist of a large IP core like a CPU, DSP unit, peripherals, standard interfaces, integrated memories SRAM, and a block of reconfigurable uncommited logic. This shift is largely because ASIC devices are capable of integrating such large blocks of system functionality and "system on a chip" requires far more than just logic blocks.

In their frequent usages in the field, the terms "gate array" and "semi-custom" are synonymous. Process engineer more commonly use the term "semi-custom" while "gate-array" is more commonly used by logic (or gate-level) designers.

By contrast, full-custom ASIC design defines all the photo lithographic layers of the device. Full-custom design is used for both ASIC design and for standard product design.

The benefits of full-custom design usually include reduced area (and therefore recurring component cost), performance improvements, and also the ability to integrate analog components and other pre-designed (and thus fully verified) components such as microprocessor cores that form a system-on-chip.

The disadvantages of full-custom design can include increased manufacturing and design time, increased non-recurring engineering costs, more complexity in the computer-aided design (CAD) system and a much higher skill requirement on the part of the design team.

However for digital-only designs, "standard-cell" cell libraries together with modern CAD systems can offer considerable performance/cost benefits with low risk. Automated layout tools are quick and easy to use and also offer the possibility to "hand-tweak" or manually optimise any performance-limiting aspect of the design.

This is effectively the same definition as a gate array.

What makes a structured/platform ASIC different from a gate array is that in a gate array the predefined metal layers serve to make manufacturing turnaround faster. In a structured/platform ASIC the predefined metallization is primarily to reduce cost of the mask sets and is also used to make the design cycle time significantly shorter as well. For example, in a cell-based or gate-array design the user often must design power, clock, and test structures themselves; these are predefined in most Structured/Platform ASICs and therefore can save time and expense for the designer compared to gate-array. Likewise, the design tools used for structured/Platform ASIC can be substantially lower cost and easier (faster) to use than cell-based tools, because the tools do not have to perform all the functions that cell-based tools do. In some cases, the structured/platform ASIC vendor requires that customized tools for their device (for example, custom physical synthesis) be used, also allowing for the design to be brought into manufacturing more quickly. ChipX, Inc. eAsic, and Triad Semiconductor are examples of vendors offering this kind of structured ASIC.

One other important aspect about structured/platform ASIC is that it allows IP that is common to certain applications or industry segments to be "built in", rather than "designed in". By building the IP directly into the architecture the designer can again save both time and money compared to designing IP into a cell-based ASIC.

The Altera technique of producing a structured cell ASIC where the cells are the same design as the FPGA, but the programmable routing is replaced with fixed wire interconnect is called HardCopy. These devices then do not need re-programming and cannot be re-programmed as an FPGA.

The Xilinx technique of producing a customer specific FPGA, that is 30% - 70% less expensive than a standard FPGA and where the cells are the same as the FPGA but the programmable capability is removed, is called EasyPath.

Cell libraries of logical primitives are usually provided by the device manufacturer as part of the service. Although they will incur no additional cost, their release will be covered by the terms of a non-disclosure agreement (NDA) and they will be regarded as intellectual property by the manufacturer. Usually their physical design will be pre-defined so they could be termed "hard macros".

What most engineers understand as "intellectual property" are IP cores, designs purchased from a third party as sub-components of a larger ASIC. They may be provided as an HDL description (often termed a "soft macro"), or as a fully routed design that could be printed directly onto an ASIC's mask (often termed a hard macro). Many organizations now sell such pre-designed IP, and larger organizations may have an entire department or division to produce such IP for the rest of the organization. For example, one can purchase CPUs, ethernet, USB or telephone interfaces. Indeed, the wide range of functions now available is a significant factor in the phenomenal increase in electronics in the late 1990s and early 2000s; as intellectual property takes a lot of time and investment to create, its re-use and further development cuts product cycle times dramatically and creates better products.

Soft macros are often process-independent, i.e., they can be fabricated on a wide range of manufacturing processes and different manufacturers.

Hard macros are process-limited and usually further design effort must be invested to migrate (port) to a different process or manufacturer.

Some manufacturers offer Multi-Project Wafers (MPW) as a method of obtaining low cost prototypes. Often called shuttles, these MPW, containing several designs, run at regular, scheduled intervals on a "cut and go" basis, usually with very little liability on the part of the manufacturer. The contract involves the assembly and packaging of a handful of devices. The service usually involves the supply of a physical design data base i.e. masking information or Pattern Generation (PG) tape. The manufacturer is often referred to as a "silicon foundry" due to the low involvement it has in the process. See also Multi Project Chip.

There are two different types of ASIC suppliers, IDM and fabless. An IDM supplier's ASIC product is based in large part on proprietary technology such as design tools, IP, packaging, and usually although not necessarily the process technology. Fabless ASIC suppliers rely almost exclusively on outside suppliers for their technology. The classfication can be confusing since several IDM's are also fabless semiconductor companies.

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Integrated circuit design

Integrated circuit design, or IC design, is a subset of electrical engineering, encompassing the particular logic and circuit design techniques required to design integrated circuits, or ICs. ICs consist of miniaturized electronic components built into an electrical network on a monolithic semiconductor substrate by photolithography.

IC design can be divided into the broad categories of digital and analog IC design. Digital IC design is used to produce components such as microprocessors, FPGAs, memories (RAM, ROM, and flash) and digital ASICs. Digital design focuses on logical correctness, maximizing circuit density, and placing circuits so that clock and timing signals are routed efficiently. Analog IC design also has specializations in power IC design and RF IC design. Analog IC design is used in the design of op-amps, linear regulators, phase locked loops, oscillators and active filters. Analog design is more concerned with the physics of the semiconductor devices such as gain, matching, power dissipation, and resistance. Fidelity of analog signal amplification and filtering is usually critical and as a result, analog ICs use larger area active devices than digital designs and are usually less dense in circuitry.

Modern ICs are enormously complicated. A large chip, as of 2006, may well have more transistors than there are people on Earth.The rules for what can and cannot be manufactured are also extremely complex. An IC process as of 2006 may well have more than 600 rules. Furthermore, since the manufacturing process itself is not completely predictable, designers must account for its statistical nature. The complexity of modern IC design, as well as market pressure to produce designs rapidly, has led to the extensive use of automated design tools in the IC design process. In short, the design of an IC using EDA software is the design, test, and verification of the instructions that the IC is to carry out.

Integrated circuit design involves the creation of electronic components, such as transistors, resistors, capacitors and the metallic interconnect of these components onto a piece of semiconductor, typically silicon. A method to isolate the individual components formed in the substrate is necessary since the substrate silicon is conductive and often forms an active region of the individual components. The two common methods are p-n junction isolation and dielectric isolation. Attention must be given to power dissipation of transistors and interconnect resistances and current density of the interconnect, contacts and vias since ICs contain very tiny devices compared to discrete components, where such concerns are less of an issue. Electromigration in metallic interconnect and ESD damage to the tiny components are also of concern. Finally, the physical layout of certain circuit subblocks is typically critical, in order to achieve the desired speed of operation, to segregate noisy portions of an IC from quiet portions, to balance the effects of heat generation across the IC, or to facilitate the placement of connections to circuitry outside the IC.

Note that the second step, RTL design, is responsible for the chip doing the right thing. The third step, physical design, does not affect the functionality at all (if done correctly) but determines how fast the chip operates and how much it costs.

This is the hardest part, and the domain of functional verification. The spec may have some terse description, such as encodes in the MP3 format or implements IEEE floating-point arithmetic. Each of these innocent looking statements expands to hundreds of pages of text, and thousands of lines of computer code. It is extremely difficult to verify that the RTL will do the right thing in all the possible cases that the user may throw at it. Many techniques are used, none of them perfect but all of them useful – extensive logic simulation, formal methods, hardware emulation, lint-like code checking, and so on.

A tiny error here can make the whole chip useless, or worse. The famous Pentium FDIV bug caused the results of a division to be wrong by at most 61 parts per million, in cases that occurred very infrequently. No one even noticed it until the chip had been in production for months. Yet Intel was forced to offer to replace, for free, every chip sold until they could fix the bug, at a cost of $475 million (US).

Here are the main steps of physical design. In practice there is not a straightforward progression - considerable iteration is required to ensure all objectives are met simultaneously. This is a difficult problem in its own right, called design closure.

Process corners provide digital designers the ability to simulate the circuit while accounting for variations in the technology process.

Before the advent of the microprocessor and software based design tools, analog ICs were designed using hand calculations. These ICs were basic circuits, op-amps are one example, usually involving no more than ten transistors and few connections. An iterative trial-and-error process and "overengineering" of device size was often necessary to achieve a manufacturable IC. Reuse of proven designs allowed progressively more complicated ICs to be built upon prior knowledge. When inexpensive computer processing became available in the 1970s, computer programs were written to simulate circuit designs with greater accuracy than practical by hand calculation. The first circuit simulator for analog ICs was called SPICE (Simulation Program with Integrated Circuits Emphasis). Computerized circuit simulation tools enable greater IC design complexity than hand calculations can achieve, making the design of analog ASICs practical. The computerized circuit simulators also enable mistakes to be found early in the design cycle before a physical device is fabricated. Additionally, a computerized circuit simulator can implement more sophisticated device models and circuit analysis too tedious for hand calculations, permitting Monte Carlo analysis and process sensitivity analysis to be practical. The effects of parameters such as temperature variation, doping concentration variation and statistical process variations can be simulated easily to determine if an IC design is manufacturable. Overall, computerized circuit simulation enables a higher degree of confidence that the circuit will work as expected upon manufacture.

A challenge most critical to analog IC design involves the variability of the individual devices built on the semiconductor chip. Unlike board-level circuit design which permits the designer to select devices that have each been tested and binned according to value, the device values on an IC can vary widely which are uncontrollable by the designer. For example, some IC resistors can vary ±20% and β of an integrated BJT can vary from 20 to 100. To add to the design challenge, device properties often vary between each processed semiconductor wafer. Device properties can even vary significantly across each individual IC due to doping gradients. The underlying cause of this variability is that many semiconductor devices are highly sensitive to uncontrollable random variances in the process. Slight changes to the amount of diffusion time, uneven doping levels, etc. can have large effects on device properties.

Fortunately for IC design, the absolute values of the devices are less critical than the identical matching of device performance. However, this fabrication variability forces certain design techniques and prevents the use of other design techniques familiar to the board-level designer.

Some of the popular electronic design automation tools are circuit simulation, logic synthesis, place and route, and design rule checking. The four largest companies selling these tools are Cadence, Synopsys, Mentor Graphics, and Magma Design Automation.

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Integrated circuit

Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery

In electronics, an integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. Integrated circuits are used in almost all electronic equipment in use today and have revolutionized the world of electronics.

A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board.

This article is about monolithic integrated circuits.

Integrated circuits were made possible by experimental discoveries which showed that semiconductor devices could perform the functions of vacuum tubes, and by mid-20th-century technology advancements in semiconductor device fabrication. The integration of large numbers of tiny transistors into a small chip was an enormous improvement over the manual assembly of circuits using discrete electronic components. The integrated circuit's mass production capability, reliability, and building-block approach to circuit design ensured the rapid adoption of standardized ICs in place of designs using discrete transistors.

There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography and not constructed one transistor at a time. Furthermore, much less material is used to construct a circuit as a packaged IC die than as a discrete circuit. Performance is high since the components switch quickly and consume little power (compared to their discrete counterparts), because the components are small and close together. As of 2006, chip areas range from a few square mm to around 350 mm², with up to 1 million transistors per mm².

The integrated circuit was conceived by a radar scientist, Geoffrey W.A. Dummer (1909-2002), working for the Royal Radar Establishment of the British Ministry of Defence, and published at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on May 7, 1952. He gave many symposia publicly to propagate his ideas.

Dummer unsuccessfully attempted to build such a circuit in 1956.

The integrated circuit can be credited as being invented by both Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor working independently of each other. Kilby recorded his initial ideas concerning the integrated circuit in July 1958 and successfully demonstrated the first working integrated circuit on September 12, 1958. Kilby won the 2000 Nobel Prize in Physics for his part of the invention of the integrated circuit. Robert Noyce also came up with his own idea of integrated circuit, half a year later than Kilby. Noyce's chip had solved many practical problems that the microchip developed by Kilby had not. Noyce's chip, made at Fairchild, was made of silicon, whereas Kilby's chip was made of germanium.

Early developments of the integrated circuit go back to 1949, when the German engineer Werner Jacobi (Siemens AG) filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on a common substrate arranged in a 2-stage amplifier arrangement. Jacobi discloses small and cheap hearing aids as typical industrial applications of his patent. A commercial use of his patent has not been reported.

A precursor idea to the IC was to create small ceramic squares (wafers), each one containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which looked 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 the project was gaining momentum, Kilby came up with a new, revolutionary design: the IC.

The aforementioned Noyce credited Kurt Lehovec of Sprague Electric for the principle of p-n junction isolation caused by the action of a biased p-n junction (the diode) as a key concept behind the IC.

See: Other variations of vacuum tubes for precursor concepts such as the Loewe 3NF.

The first integrated circuits contained only a few transistors. Called "Small-Scale Integration" (SSI), they used circuits containing transistors numbering in the tens.

SSI circuits were crucial to early aerospace projects, and vice-versa. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated the integrated-circuit technology, while the Minuteman missile forced it into mass-production.

These programs purchased almost all of the available integrated circuits from 1960 through 1963, and almost alone provided the demand that funded the production improvements to get the production costs from $1000/circuit (in 1960 dollars) to merely $25/circuit (in 1963 dollars). They began to appear in consumer products at the turn of the decade, a typical application being FM inter-carrier sound processing in television receivers.

The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called "Medium-Scale Integration" (MSI).

They were attractive economically because while they cost little more to produce than SSI devices, they allowed more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate components), and a number of other advantages.

Further development, driven by the same economic factors, led to "Large-Scale Integration" (LSI) in the mid 1970s, with tens of thousands of transistors per chip.

Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching 10000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors.

The final step in the development process, starting in the 1980s and continuing through the present, was "Very Large-Scale Integration" (VLSI). This could be said to start with hundreds of thousands of transistors in the early 1980s, and continues beyond several billion transistors as of 2007.

There was no single breakthrough that allowed this increase in complexity, though many factors helped. Manufacturing moved to smaller rules and cleaner fabs, allowing them to produce chips with more transistors with adequate yield, as summarized by the International Technology Roadmap for Semiconductors (ITRS). Design tools improved enough to make it practical to finish these designs in a reasonable time. The more energy efficient CMOS replaced NMOS and PMOS, avoiding a prohibitive increase in power consumption. Better texts such as the landmark textbook by Mead and Conway helped schools educate more designers, among other factors.

In 1986 the first one megabit RAM chips were introduced, which contained more than one million transistors. Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005. The trend continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors .

To reflect further growth of the complexity, the term ULSI that stands for "Ultra-Large Scale Integration" was proposed for chips of complexity of more than 1 million transistors.

Wafer-scale integration (WSI) is a system of building very-large integrated circuits that uses an entire silicon wafer to produce a single "super-chip". Through a combination of large size and reduced packaging, WSI could lead to dramatically reduced costs for some systems, notably massively parallel supercomputers. The name is taken from the term Very-Large-Scale Integration, the current state of the art when WSI was being developed.

System-on-a-Chip (SoC or SOC) is an integrated circuit in which all the components needed for a computer or other system are included on a single chip. The design of such a device can be complex and costly, and building disparate components on a single piece of silicon may compromise the efficiency of some elements. However, these drawbacks are offset by lower manufacturing and assembly costs and by a greatly reduced power budget: because signals among the components are kept on-die, much less power is required (see Packaging, above).

Three Dimensional Integrated Circuit (3D-IC) has two or more layers of active electronic components that are integrated both vertically and horizontally into a single circuit. Communication between layers uses on-die signaling, so power consumption is much lower than in equivalent separate circuits. Judicious use of short vertical wires can substantially reduce overall wire length for faster operation.

Among the most advanced integrated circuits are the microprocessors or "cores", which control everything from computers to cellular phones to digital microwave ovens. Digital memory chips and ASICs are examples of other families of integrated circuits that are important to the modern information society. While cost of designing and developing a complex integrated circuit is quite high, when spread across typically millions of production units the individual IC cost is minimized. The performance of ICs is high because the small size allows short traces which in turn allows low power logic (such as CMOS) to be used at fast switching speeds.

ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip. This increased capacity per unit area can be used to decrease cost and/or increase functionality—see Moore's law which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the cost per unit and the switching power consumption go down, and the speed goes up. However, ICs with nanometer-scale devices are not without their problems, principal among which is leakage current (see subthreshold leakage for a discussion of this), although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of high-k dielectrics. Since these speed and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the expected progress over the next few years, is well described by the International Technology Roadmap for Semiconductors (ITRS).

Only a half century after their development was initiated, integrated circuits have become ubiquitous. Computers, cellular phones, and other digital appliances are now inextricable parts of the structure of modern societies. That is, modern computing, communications, manufacturing and transport systems, including the Internet, all depend on the existence of integrated circuits. Indeed, many scholars believe that the digital revolution—brought about by the microchip revolution—was one of the most significant occurrences in the history of humankind.

Integrated circuits can be classified into analog, digital and mixed signal (both analog and digital on the same chip).

Digital integrated circuits can contain anything from one to millions of logic gates, flip-flops, multiplexers, and other circuits in 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 micro controllers work using binary mathematics to process "one" and "zero" signals.

Analog ICs, such as sensors, power management circuits, and operational amplifiers, work by processing continuous signals. They perform functions like amplification, active filtering, demodulation, mixing, etc. Analog ICs ease the burden on circuit designers by having expertly designed analog circuits available instead of designing a difficult analog circuit from scratch.

ICs can also combine analog and digital circuits on a single chip to create functions such as A/D converters and D/A converters. Such circuits offer smaller size and lower cost, but must carefully account for signal interference.

The semiconductors of the periodic table of the chemical elements were identified as the most likely materials for a solid state vacuum tube by researchers like William Shockley at Bell Laboratories starting in the 1930s. Starting with copper oxide, proceeding to germanium, then silicon, the materials were systematically studied in the 1940s and 1950s. Today, silicon monocrystals are the main substrate used for integrated circuits (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 the highest-speed integrated circuits. It took decades to perfect methods of creating crystals without defects in the crystalline structure of the semiconducting material.

The main process steps are supplemented by doping and cleaning.

Mono-crystal silicon wafers (or for special applications, silicon on sapphire or gallium arsenide wafers) are used as the substrate. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon, insulators or metal (typically aluminum) tracks deposited on them.

Since a CMOS device only draws current on the transition between logic states, CMOS devices consume much less current than bipolar devices.

A random access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even 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" 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 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 aluminum (or gold) bond wires which are welded to pads, usually found around the edge of the die. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Test cost can account for over 25% of the cost of fabrication on lower cost products, but can be negligible on low yielding, larger, and/or higher cost devices.

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 the dual in-line package (DIP), first in ceramic and later in plastic. 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 small-outline integrated circuit -- a carrier which occupies an area about 30 – 50% less than an equivalent DIP, with a typical thickness that is 70% less. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches.

Small-outline integrated circuit (SOIC) and PLCC packages. In the late 1990s, PQFP and TSOP packages became the most common for high pin count devices, though PGA packages are still often used for high-end microprocessors. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to land grid array (LGA) packages.

Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball Grid Array packages, which allow for 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 the entire die rather than being confined to the die periphery.

Traces out of the die, through the package, and into the printed circuit board have very different electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself.

When multiple dies are put in one package, it is called SiP, for System In Package. When multiple dies are combined on a small substrate, often ceramic, it's called an MCM, or Multi-Chip Module. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy.

In the 1980s programmable integrated circuits 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 single chip to be programmed to implement different LSI-type functions such as logic gates, adders, and registers. Current devices named FPGAs (Field Programmable Gate Arrays) can now implement tens of thousands of LSI circuits in parallel and operate up to 550 MHz.

The techniques perfected by the integrated circuits industry over the last three decades have been used to create microscopic machines, known as MEMS. These devices are used in a variety of commercial and military applications. Example commercial applications include DLP projectors, inkjet printers, and accelerometers used to deploy automobile airbags.

In the past, radios could not be fabricated in the same low-cost processes as microprocessors. But since 1998, a large number of radio chips have been developed using CMOS processes. Examples include Intel's DECT cordless phone, or Atheros's 802.11 card.

Future developments seem to follow the multi-microprocessor paradigm, already used by the Intel and AMD dual-core processors. Intel recently unveiled a prototype, "not for commercial sale" chip that bears a staggering 80 microprocessors. Each core is capable of handling its own task independently of the others. This is in response to the heat-versus-speed limit that is about to be reached using existing transistor technology. This design provides a new challenge to chip programming. X10 is the new open-source programming language designed to assist with this task.

Ever since ICs were created, some chip designers have used the silicon surface area for surreptitious, non-functional images or words. These are sometimes referred to as Chip Art, Silicon Art, Silicon Graffiti or Silicon Doodling. For an overview of this practice, see the article The Secret Art of Chip Graffiti, from the IEEE magazine Spectrum and the Silicon Zoo.

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Source : Wikipedia