What Is Integrated Circuit ?
The world of electronics has experienced plenty of tech advances since mankind started to use electronic devices. However, integrated Circuit represent one of the most significant and transformative among these tech developments. ICs have not only revolutionized electronics but altered its course forever. The miniaturization or reduction of electronics from large to tiny pieces will inform any present and future innovations. But what is an integrated circuit? What is its role in electronics?
Integrated Circuit (ICs)
The recent history of integrated Circuit can get traced to vacuum tubes. Vacuum tubes played a fundamental role in earlier electronic equipment and devices. However, the origin stems from the transistor invention in the 1947 Shockley WB and his crew. The team discovered that electrons could conjure up barriers on specific crystal surfaces under appropriate circumstances. Understanding how to regulate the electricity flow by manipulating the crystal barrier came as a significant breakthrough. It allowed for developing a device (transistor) responsible for specific electrical functions like signal amplification, which vacuum tubes executed before.
An integrated circuit represents a single fabricated unit containing an assembly of electronic parts or components. The miniaturized passive devices such as resistors and capacitors, besides the active devices like diodes and transistors and their interconnections, get built on the thin semiconductor substrate (mostly silicon). It ensures that the resulting chip is of a tiny size (potentially a few sq. centimetres or millimetres).
Unlike the earlier used vacuum tubes, integrated Circuit consume less power and dissipate lesser amounts of heat. It is also reliable compared to vacuum tubes. Integrated Circuit utilize a characteristically different design that deploys a hybrid solid-state format that combines ICs with discrete components. The connections between components are tiny, and you cannot see them with the naked eye.
Integrated Circuit are crucial in electronics that almost every, if not all, electronic equipment and devices we interact with daily.
Classification of Integrated Circuit
Suppose you want to design a chip for your electronic use. It always helps to understand the different classifications and types of ICs. We can classify integrated Circuit into different size classes. It includes SSI (2 to 30 gates for every electronic chip), MSI (containing 30 to 300 gates for each chip), and LSI (containing 300 to 3000 gates for every chip). Another class is the VLSI, with over 3000 gates for every chip.
Integrated Circuit Types
The type of IC depends on the technique or method used to fabricate them. Because of this, the different types include the following.
- Thick and thin-film integrated Circuit
- Monolithic integrated circuit
- Multichip or hybrid integrated Circuit
Thick and Thin ICs
It is a distinctive type of integrated circuit that passive components like capacitors and resistors get integrated. However, active components like transistors and diodes get connected as distinct components to establish a complete and singular circuit. It always implies a mere combination of discrete and integrated components for thick and thin integrated Circuit fabricated commercially.
Thin and thick ICs possess similar attributes and appearances, though they differ in the film deposition method. It is from this basis that you can distinguish a thin integrated circuit from a thick integrated circuit. Thin-film integrated Circuit get produced by the deposition of conductive material on a ceramic or glass surface base. The thickness gets varied (of the deposited film) on the ceramic or glass materials having diverse resistivity. In doing so, it becomes possible to manufacture the passive components.
A thick film integrated circuit, on the other hand, uses the silk printing approach to develop the anticipated circuitry pattern on the ceramic material or substrate. It is from this printing technique that it at times gets inferred to as printed thin-film. Screens often get developed of a fine wire mesh (of stainless steel) with connections containing pastes of dielectric, resistive, and conductive properties. It then gets passed through a high-temperature furnace to ensure the fusion of the films to the material or substrate post-printing gets completed.
Monolithic Integrated Circuit
Monolithic ICs have passive and active components, discrete parts, and interconnections on a single silicon chip. It all means that a monolithic integrated circuit is one (a circuit) built on a singular crystal.
Monolithic integrated Circuit are standard in today’s electronic environment. Some of the aspects influencing their popularity is their reliability and the cheap cost of producing these ICs. It is an IC type that finds application as voltage regulators, amplifiers, computer Circuit, and AM receivers. But despite such comprehensive benefits besides the wide-ranging application areas, the monolithic IC has some drawbacks. It primarily comes from its low or poor power rating, besides the impossibility of fabricating insulators, etc.
Multichip or Hybrid Integrated Circuit
It is a type of integrated circuit containing more than one chip, and these are often interconnected. Active components contained in a hybrid integrated circuit are the diffused diodes or transistors. On the other hand, the passive parts or components are the diffused capacitors or resistors on a singular chip.
The components in a multi or hybrid IC gets connected through metallized patterns. Such IC types find application in high power amplifiers of 5W to an excess of 50W.
Additionally, it is prudent to note that the three classifications are not exhaustive as other categorizations of integrated Circuit exist. It includes digital integrated Circuit, analogue integrated Circuit, and mixed-signal integrated Circuit.
Digital Integrated Circuit
A digital integrated circuit is a special type of IC that functions based on the basic digital system. The two levels of 1’s and 0’s define the circuit, which infers to the “off” and “on” or the “high” and “low” respectively. An excellent example of a digital IC includes a microcontroller and a microprocessor that possess millions of logic gates and flip flops.
Digital integrated Circuit handle discrete signals like binary values where the “true/false” logical functions get utilized. Additionally, logic functions like “OR,” “NOT,” and “AND” are critical in developing the functionality used in modern digital systems. The logic functions (basic Boolean functions) get implemented by transistors. We can also utilize transistors in building electronic components. Currently, integrated Circuit combine plenty of small-sized transistors (up to billions in number) and other components on a tiny chip in realizing a specific functionality. Such functionality can prove simple (like a “NOT” basic logic function) or a complicated one (microprocessor)
Digital integrated Circuit get distinguished by a mixture of numbers and/or characters. For instance, microprocessors from Intel have diverse names based on different schemes. Pentium represents one of these critical processors. It is a designation of the plastic casing containing the semiconductor LC, which has the processor. Before, numbers named the respective processors and, in some instances, a combination of letters and digits.
Some examples of digital ICs include CMOS, MOS, TTL, etc., with each having its distinctive attributes and advantages.
Families of Digital Integrated Circuit
Logic families are groups of electronic logic gates. Every family possesses its distinctive level of discrete logic gates, individual components, power supply, features, benefits, and drawbacks. The voltage range within a particular family can prove high or low level. Some of the families include the following.
DL or Diode Logic
Diodes and register implement the logic. Diodes are instrumental in performing “AND” and “OR” operations, besides logic switch. It always becomes vital to ensure that the diode has a forward bias for conduction. While beneficial, it cannot perform the “NOT” function, besides incapability to operate in many states. It also tends to degrade signals quickly.
RTL or Resistor-Transistor Logic
Transistors and registers are good in implementing logic in this case. Transistors combine inverted signals with amplified inputs. RTLs are simple to design and economical but with slower speeds. Additionally, RTLs need large amounts of current, and they can be useful as the interface between digital and linear Circuit.
DTL or Diode Transistor Logic
Diodes and registers get utilized in implementing logic. DTLs have benefits over RTL and DL. Its diodes can execute “OR” and “AND” operations besides having a transistor and the capacity to amplify the output signal. The logic inversion present in DTL allows for signal restoration to a full logic level, primarily upon incorporating a transistor at the logic gate’s output. The “OR” function gets carried out by diodes instead of resistors, and it removes the interaction amongst input signals.
TTL or Transistor-Transistor Logic
TTLs implement logic besides bipolar transistors in contracting integrated Circuit. It comes as either standard, high speed, low power, or Schottky TTLs. However, the family represents a popular choice among people in the electronic industry.
ECL or Emitter Coupled Logic
The logic comes unstructured and possesses the benefits of high speeds and a low propagation delay.
CMOS or Complementary Metal Oxide Semiconductor Logic
It is a popular logic option for most people because of its low power intake and high fan-out. As a result, it represents the most reliable among the logic families.
Designing Digital Circuit
Digital Circuit contain millions of components compared to their analogue counterparts. As a result, the design process needs to assume a model that reuses and copies similar circuit functions. It mostly uses digital design programs containing libraries of already-structured circuit components. Such libraries have components with similar heights besides containing contact points in designated locations. You need to consider other or extra rigid conformities to ensure they all fit together, notwithstanding the computer configuration’s layout.
While software design suites such as SPICE play an instrumental role in designing analogue ICs, the complex nature of digital ICs needs a less comprehensive approach. Consequently, digital analysis programs tend to ignore specific components when it comes to mathematical models of the preconfigured electronic circuit blocks.
It is, however, essential to note that digital ICs are only designed and deployed based on the circuit’s needs. Further, the needs for digital IC design are less demanding when it comes to time, innovation, teamwork, and experience as opposed to analogue Circuit.
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Analog Electronic Circuit
It represents a complex mix of op-amps, caps, resistors, and other basic components. Analog electronic Circuit can come complex or straightforward based on the design needs. For instance, it can only combine two resistors to divide voltage or come complex with an elegant build consisting of numerous components.
Analog electronic Circuit can isolate, attenuate, amplify, distort, or modify signals. Such Circuit can also convert the original signals into digital signals. It is a tough circuit to design because of the precision needed to design compared to digital Circuit. While important, contemporary Circuit tend to prove digital than analogue. In instances where analogue Circuit exist, they still deploy microprocessor or digital techniques in improving performance.
Analog electronic Circuit have two types in active and passive electronic Circuit. Passive electronic Circuit do not consume any power, while active electronic Circuit consume some power. The importance of analogue Circuit and components cannot get understated as much as they are simple. It helps filter continuous analogue signals because it has a filter instrumental in removing all unwanted frequency content. It is also cheaper and simpler to use as opposed to digital Circuit.
Analogue Circuit have a more efficient mode of switching power than digital signal switches. It especially becomes important when dealing with power switching from zero to 400V. Additionally, the power delivery mode (continuous) in DC and AC systems need analogue components because of their characterization and durability. Filtering of noise post sampling also becomes important before A/D and post D/A in hybrid systems. Such a system needs digital-to-analogue and analogue-to-digital converters.
Designing Analog Circuit
Analogue Circuit prove infinitely variable when it comes to current or voltage uptake besides modifying it into a helpful form. It can include amplification of the signal, comparison with other signals, mixed with others, separated from others, examined for their value, or manipulated. Because of this, the design process for analogue Circuit needs thorough consideration. Some aspects to consider should include the type of every particular component, placement, size, and connection. As a designer, unique decisions like how wide one particular connection needs to prove. It can also include deciding whether to lay a particular resistor perpendicularly or parallel to another, etc. Each detail is important in affecting the eventual performance of the electronic product.
Current design requirements for analogue Circuit have transcended the simple calculation that existed earlier. It entails more complex equations to check the subtle effects that would otherwise not appear in laboratory measurements. All the complex calculations get accounted for by computer programs, especially those specializing in public-domain circuit analysis.
Integrated Circuit Fabrication
Production of integrated Circuit always starts with the design and ends up with fabrication. As an IC designer, understanding both processes become pivotal in ensuring quality integrated Circuit that suit the intended application. It also helps identify a suitable electronic circuit manufacturer that will meet your quality specification and your budget as well. So what are some of the important IC fabrications steps to have in mind?
While understanding each of the above-stated steps is priceless, you can always learn more about IC fabrication from RayMing PCB and Assembly website. It not only deepens your knowledge about the world-class facilities deployed in the fabrication process but also the specialized approach.
Steps
Developing the base wafer
The base wafer represents the substrate upon which the integrated circuit gets build. It is prudent to ensure the purity of this semiconductor material for consistent performance. Czochralski initially discovered the basic approach in developing large and single silicon crystals, hence the name Czochralski method. It features high temperatures (about 1500 degrees Celsius) to heat electronic-grade silicon in a fused quartz vessel. While lengthy and slow, after a few days, the large silicon crystal ingot gets sliced into wafers (thin). It is the wafers that the integrated Circuit get fabricated upon simultaneously.
Layer building
It comprises the next step as every component, like capacitors, diodes, transistors, etc., we can easily build using the n- and p-type semiconductors. Integrated Circuit comprise multiple layers that get built on a semiconductor substrate. The building of layers happens one at a time, and perhaps the final IC product can possess up to over 30 layers. The location of each p- and n-type needs early stipulation, especially on every layer.
Etching of the layers happens through geometrical shapes and lines in specific spots designated for material deposition. Further, the wafer can get changed either through deposition, etching or implantation. Deposition implies the application of thin films of substance on the wafer. It can happen through physical or chemical reactions.
On the other hand, etching implies removing material by etching using RIE or reactive ion etching. Implantation, however, is a wafer modifying approach by bombarding the surface with more atoms. The embedding of extra atoms changes the material’s characteristics and develops p- and n-type materials.
Integrated Circuit Price
The fabrication process of an integrated circuit is often a complex process, depending on the type of IC you decide to go for. The materials, electronic components, technology and equipment needed for the design and fabrication process often contribute the most to the pricing of ICs. However, integrated Circuit prices are lower compared to discrete Circuit because of several reasons.
Firstly, ICs and their components are tiny and thus get printed by photolithography into a singular unit. It is different to getting constructed methodically (a transistor after a transistor), which becomes cumbersome and time-consuming. Secondly, packaged integrated Circuit utilize less material compared to their discrete counterparts owing to their size. Consequently, the cost of production reduces, and this also impacts the price.
IC prices, besides the productions costs, will also differ based on the manufacturing company and the geographical region. Geographical locations influence aspects such as delivery costs, accessibility and transport costs of IC raw materials, accessibility to qualified and cheap labour, access to technology, etc. The manufacturing company influences the cost based on its branding and stature in the circuit industry. More reputable companies offer better quality products in large volumes and thus a slightly favourable IC cost.
Functions of Integrated Circuit
Integrated Circuit are crucial in almost all electronic equipment and devices. ICs act as the primary component that condenses functionality for high-level tasks. It includes signal processing, amplification, refined digital calculations as with microprocessors, etc. The possibility of getting an electronic product that does not rely on an integrated chip is slim in this dispensation.
Integrated Circuit are also instrumental in the miniaturization of electronic products, enhancing their performance, reducing costs etc.
For instance, the cost reduction function of integrated Circuit comes about by offering the relatively cost-effective option of collecting a large amount of electronic and semiconductor components, besides mounting them on a circuit board. In case you had to implement all these in discrete components, it could amount to about 250. However, in ICs, the components or parts number can reduce to around 10. It implies that the overall material count reduces with integrated Circuit, and the production process stages also get simplified.
The IC’s performance boost function becomes a reality through the specialized circuit operation within the chip. For instance, numerous radio frequency applications become too expensive to execute as discrete parts or components. As a result, whenever a demand shoots for a particular feature, the industry engineers ways of building integrated Circuit for those specific applications. An excellent example encompasses the development of MSI or medium-scale integration chips by manufacturers to support sound applications in PCs. It resulted from the introduction of sound cards for PCs. Another critical performance boost example includes the reduced power consumption of the same product that brought a higher energy or power efficiency.
Final Thoughts
The current trend in the electronics industry entails miniaturization, which integrated Circuit play a key role in. however, the bottom-line for most industry players is reducing the costs. While any renowned electronic equipment or device will always justify the resources poured into developing it (conceptualizing, designing, implementing), the integrated circuit aims to optimize the production process of electronic products. Therefore, endless possibilities exist in the delivery of low cost and performance enhanced miniaturized electronic products.
Integrated Circuit are the backbone of every modern electronic product. But in understanding the different facets of ICs, will champion your capacity to design and fabricate your integrated circuit for your specific application. Hopefully, you are wiser now.