PREMLILA VITHALDAS POLYTECHNIC S. N. D. T. Women’s University, Juhu Campus, Santacruz (West),

Mumbai- 400 049. Maharashtra (INDIA).

Integrated Circuit

PREPARED BY

Miss. Rohini A. Mane (G. R. No.: 15070113)

Miss. Anjali J. Maurya (G. R. No.: 15070114)

Miss. Tejal S. Mejari (G. R. No.: 15070115)

. .

Diploma in Electronics: Semester VII (June - November 2018)

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Introduction:

The separately manufactured components like

resistor, capacitor, diode, and transistor are joined by

wires or by printed circuit boards (PCB) to form

circuit. These circuits are called discrete circuits and

they have following disadvantages.

1. In a large electronic circuit, there may be very

large number of components and as a result

the discrete assembly will occupy very large

space.

2. They are formed by soldering which causes a

problem of reliability.

To overcome these problems of space

conservation and reliability the integrated circuit were

developed(IC).

Figure1 Integrated Circuit

An integrated circuit (IC), sometimes called a

chip or microchip, is a semiconductor wafer on which

thousands or millions of tiny resistors, capacitors, and

transistors are fabricated. An IC can function as an

amplifier, oscillator, timer, counter, computer

memory, or microprocessor. A particular IC is

categorized as either linear (analog) or digital,

depending on its intended application.

1. In IC, the various components are integral

part of a small semiconductor chip and the

individual components cannot be removed

for repair and replacement as in discrete

circuit.

2. It combines both active elements like diode

and transistor with passive components like

resistor and capacitors in monolithic circuit.

Their size is very small. To see connections

between their various components, a

microscope is needed.

3. All the components are formed within the

chip and no components is seen projected

above the surface of the chip.

History:

An integrated circuit is a thin slice of silicon

or sometimes another material that has been specially

processed so that a tiny electric circuit is etched on its

surface. The circuit can have many millions of

microscopic individual elements, including

transistors, resistors, capacitors, and conductors, all

electrically connected in a certain way to perform

some useful function.

Figure2 The first Integrated circuit

The first integrated circuits were based on the

idea that the same process used to make clusters of

transistors on silicon wafers might be used to make a

functional circuit, such as an amplifier circuit or a

computer logic circuit. Slices of the semiconductor

materials silicon and germanium were already being

printed with patterns, the exposed surfaces etched with

chemicals, and then the pattern removed, leaving

dozens of individual transistors, ready to be sliced up

and packed individually. But wires, a few resistors and

capacitors might later connect those same transistors

to make a circuit.

The idea occurred to a number of inventors at

the same time, but the first to accomplish it were Jack

Kilby of Texas Instruments and Robert Noyce of

Fairchild Semiconductor Incorporated. The idea

caught on like wildfire because the integrated circuit

had many of the advantages that had made the

transistor attractive earlier. These advantages included

small size, high reliability, low cost, and small power

consumption. However, these circuits were difficult to

make because if one component of the chip was faulty,

the whole chip was ruined. As engineers got better and

better at squeezing more and more transistors and

other components onto a single chip, the problems of

actually making these chips increased. When the

transistors were shrunk down to microscopic size,

even the smallest bit of dust could ruin the chip. That's

why today, chips are made in special "clean rooms"

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where workers wear the "bunny suits" that we often

see on TV.

Compared to the original integrated circuit,

which was a simple device with just a few

components, the number of components on today's'

integrated circuits is amazing. In the 1960s, an

engineer named Gordon Moore predicted that the

number of elements on a chip would double every year

(later revised to every two years) into the foreseeable

future. "Moore's Law" has held true so far. By the

beginning of the twenty-first century, the Intel

Pentium chip had over 100 million transistors on it,

with the total number of components including

resistors, capacitors, and conductors being even larger.

Like many inventions, the integrated circuit

was really a matter of time. Kilby drew upon the works

of an Englishman, Geoffrey Dummer, when coming

up with the idea of the integrated circuit. In the early

1950s, Dummer proposed electronics built from a

single block of components, but he lacked the

technique to make it into a reality.

Figure3 Kilby and Noyce received the Draper Prize in

1989.

Then there was Robert Noyce (Noyce and

Kilby received the Draper Prize together in 1989).

Noyce, often referred to as “the Mayor of Silicon

Valley,” is credited as the co-inventor of the integrated

circuit, and for good reason.

Noyce came up with the same idea

completely independently, used silicon instead of

germanium (silicon operates at higher temperatures),

and had an altogether more-refined design.

Oh, and he went on to co-found Intel in 1968

with colleague Gordon Moore. Intel, of course, created

the first microprocessor, equally important to modern

computing.

And you probably know Texas Instruments

because—at one point—you took a math class and

used one of the company’s calculators. Oddly enough,

Kilby gets credit for that one as well.

Figure4 A look inside Kilby’s original Texas

Instruments electronic handheld calculator.

He and two co-workers, Jerry Merryman and

James Van Tassel, developed the electronic handheld

calculator because Texas Instruments needed a way to

sell the public on the consumer benefits of the

integrated circuit.

The beginnings of the IC really started with

the inherent limitations of the vacuum tube, a large,

bulky device that preceded the transistor which

eventually led to the microchip. Vacuum tubes worked

as an electronic circuit, but they required warming up

before they could operate. Plus, they were quite

vulnerable to being damaged or destroyed even by

minor bumps or impacts.

With the limitations in mind, German

engineer Werner Jacobi filed a patent in 1949 for a

semiconductor that operated similarly to the current

integrated circuit. Jacobi lined up five transistors and

used them in a three-stage arrangement on an

amplifier. The result as Jacobi recognized was the

ability to shrink devices such as hearing aids and make

them cheaper to produce.

Despite Jacobi’s invention, there appeared to

be no immediate interest. Three years later, Geoffrey

Dummer who worked for the Royal Radar

Establishment as part of the Ministry of Defence in

Britain proposed the first fully conceived idea for the

integrated circuit. However, despite giving lectures

about his ideas, he was never able to build one

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successfully. It was the failure to actually create an IC

on his own that led to the movement towards the chip

overseas to America.

Invention:

Figure5 Robert Noyce (left) and Jack Kilby (Courtesy

of Intel and Texas Instruments)

As with many inventions, several people had

the idea for an integrated circuit at almost the same

time. In 1950s many inventors realize, that despite of

the fact, that transistors had become commonplace in

everything from radios to phones to computers, and

that transistors were smaller than vacuum tubes, for

some of the newest electronics, they weren't small

enough. There was a limit on how small you could

make each transistor, since after it was made it had to

be connected to wires and other electronics. The

transistors were already at the limit of what steady

hands and tiny tweezers could handle. So, scientists

wanted to make a whole circuit—the transistors, the

wires, everything else they needed—in a single blow.

If they could create a miniature circuit in just one step,

all the parts could be made much smaller.

Figure6 British engineer Geoffrey Dummer

The first man, who must be credited for the

conceptualisation of the integrated curcuit, is the

British engineer Geoffrey Dummer (see yhe nearby

photo). Geoffrey William Arnold Dummer (1909–

2002) is a British electronics author and consultant,

who passed the first radar trainers and became a

pioneer of reliability engineering at the

Telecommunications Research Establishment in

Malvern in the 1940s. His work with colleagues at

TRE led him to the belief that it would be possible to

fabricate multiple circuit elements on and into a

substance like silicon. In 1952 he presented his work

at a conference in Washington, DC, in which he states:

“With the advent of the transistor and the work on

semi-conductors generally, it now seems possible to

envisage electronic equipment in a solid block with no

connecting wires. The block may consist of layers of

insulating, conducting, rectifying and amplifying

materials, the electronic functions being connected

directly by cutting out areas of the various layers”.

This is now generally accepted as the first public

description of an integrated circuit.

At a later date Dummer said, “It seemed so

logical to me; we had been working on smaller and

smaller components, improving reliability as well as

size reduction. I thought the only way we could ever

attain our aim was in the form of a solid block. You

then do away with all your contact problems, and you

have a small circuit with high reliability. And that is

why I went on with it. I shook the industry to the bone.

I was trying to make them realise how important its

invention would be for the future of microelectronics

and the national economy”.

In September 1957, Dummer presented a model to

illustrate the possibilities of solid-circuit techniques—

a flip-flop in the form of a solid block of

semiconductor material, suitably doped and shaped to

form four transistors. Four resistors were represented

by silicon bridges, and other resistors and capacitors

were deposited in film form directly onto the silicon

block with intervening insulating films.

Dummer's ideas however remained

unrealized and relatively unknown, because the UK

military failed to perceive any operational

requirements for ICs, and UK companies were

unwilling to invest their own money. Dummer later

said: “I have attributed it to war-weariness in one of

my books, but that is perhaps an excuse. The plain fact

is that nobody would take the risk. The Ministry

wouldn’t place a contract because they hadn’t an

application. The applications people wouldn’t say we

want it, because they had no experience with it. It was

a chicken-and-egg situation. The Americans took

financial gambles, whereas this was very slow in this

country”.And the Americans were again faster and

took financial gambles.

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One day in late July of 1958, the engineer

Jack Kilby (see biography of Jack Kilby) was sitting

alone at a small, but innovative company in Dallas,

Texas—Texas Instruments. In 1954 the company had

been involved with manufacturing the first transistor

pocket radio, which was enormously successful.

Executives at Texas Instruments believed that the

possibilities of electronic circuits were nearly endless.

In May of 1954 company engineers perfected a

process for making transistors out of silicon—an

improvement which made them much less prone to fail

when they got hot. In their research they discovered

that several electrical components could be built from

silicon, although at the time they were only interested

in transistors.

Kilby had been hired only a month earlier and

so he wasn't able to take vacation time when

practically everyone else did. The halls were deserted,

and he had lots of time to think. As he remembered

later: "As a new employee, I had no vacation time

coming and was left alone to ponder the results of an

IF amplifier exercise. The cost analysis gave me my

first insight into the cost structure of a semiconductor

house." It suddenly occurred to him that all parts of a

circuit, not just the transistor, could be made out of

silicon. At the time, nobody was making capacitors or

resistors out of semiconductors. If it could be done

then the entire circuit could be built out of a single

crystal—making it smaller and much easier to

produce. Kilby's solution to this problem has come to

be called the monolithic idea. He listed all the

electrical components that could be built from silicon:

transistors, diodes, resistors and capacitors.

What was the reaction of his colleagues?

Kilby recalled: There were a number of objections.

Most people thought that you would never be able to

make them in quantity. At that time less than 10

percent of the transistors at the end of the line were

likely to be good. The thought that you would put

several on a chip seemed like madness.

Kilby then conceived the idea of constructing

a single device with all the needed parts that could be

made of silicon and soldering it to a circuit board. He

understood that if he could eliminate the wires

between the parts, he could squeeze more parts into a

smaller space, thus solving the obstacle of

manufacturing complex transistor circuits. When he

presented this smash idea to his boss, he liked it, and

told him to get to work. By September 12, Kilby had

built a working model (see the lower photo), and on

February 6th, Texas Instruments filed a patent. Their

first Solid Circuit the size of a pencil point (11-by-1.5-

millimetres in size ), was shown off for the first time

in March, 1960.

Figure7 The original integrated circuit of Jack Kilby

But over in California, another man had

similar ideas. In January of 1959, Robert Noyce (see

his biography) was working at a small startup

company—Fairchild Semiconductor, which he and 7

of his colleagues established in 1957, leaving

Shockley Semiconductor. He also realized a whole

circuit could be made on a single chip. While Kilby

had hammered out the details of making individual

components, Noyce thought of a much better way to

connect the parts. That spring, Fairchild began a push

to build what they called "unitary circuits" and they

also applied for a patent on the idea. Knowing that TI

had already filed a patent on something similar,

Fairchild wrote out a highly detailed application,

hoping that it wouldn't infringe on TI's similar device.

All that detail paid off. On April 25, 1961, the

patent office awarded the first patent for an integrated

circuit to Robert Noyce (see the U.S. patent 2981877

patent of Noyce) while Kilby's application, filed 5

months earlier than Noyce's, was still being analyzed

and the patent was granted as late as June, 1964 (see

the U.S. patent 3138743 patent of Kilby). Today, both

men are acknowledged as having independently

conceived of the idea, but the real acknowledgement

came too late, in 2000, when only Kilby became a

Nobel Prize laureate for his invention of the integrated

circuit, while Noyce died in 1990 and didn't manage to

be honored with this prestigious award.

The companies Fairchild Electronics and

Texas Instruments had a court fight that was not settled

until 1966, by which time integrated circuit chips had

become a multi-billion dollar industry. In the summer

of 1966 executives of the two companies had made an

agreement to share ownership by granting production

licenses to each other. Any other company that wanted

to produce integrated circuits had to pay both Texas

Instruments and Fairchild. As for Kilby, the scientific

community informally agreed that both he and Noyce

5

had invented the chip and that they both deserved

credit.

Kilby and Texas Instruments had made a big

breakthrough. But while the U.S. Air Force showed

some interest in TI's integrated circuit, industry

reacted skeptically. Indeed the IC and its relative

merits "provided much of the entertainment at major

technical meetings over the next few years," as Kilby

wrote later.

Figure8 SN510

Since TI and Fairchild were the co-inventors

of the IC, one might expect that they would release the

first commercial devices, and in fact this was so. In

March, 1960, Texas Instruments announced the

introduction of the earliest product line of integrated

logic circuits. TI's trade name is Solid Circuits for this

line. This family, called the series 51, utilized the

modified DCTL circuit and the SN510 and SN 514,

were the first integrated circuits to orbit the Earth,

aboard the IMP satellite, launched by the US on

November 27, 1963 (see the nearby photo). Fairchild's

prototype chips were announced in November 1960,

and the company had introduced its first commercial

integrated circuit, the same device as Dummer's a

decade ago, a flip-flop (the basic storage element in

computer logic), at an industry convention in New

York in March 1961. Soon other firms began to

develop ICs, i.e. Motorola and Signetics, which

announced their first chips in 1962.

The integrated circuit first won a place in the

military market through programs such as the first

computer using silicon chips for the Air Force in 1961

and the Minuteman Missile in 1962. Recognizing the

need for a "demonstration product" to speed

widespread use of the IC, Patrick Haggerty, former TI

chairman, challenged Kilby to design a calculator as

powerful as the large, electro-mechanical desktop

models of the day, but small enough to fit in a coat

pocket. In 1965, Kilby was put in charge of directing

a team to develop the world's first pocket calculator,

made feasible by the microchip. Within a year Kilby

and his colleagues Merryman, and Van Tassel had a

working prototype, and a year later they filed for a

patent. The resulting first in the world electronic hand-

held calculator (see the lower photo), of which Kilby

is a co-inventor, successfully commercialized the

integrated circuit in 1967. The so called Pocketronic

was launched on April 14 1971, weighed a little over

1 kg, cost $150, and could only perform the four main

arithmetical functions. Displaying the output remained

a problem. Light-emitting diode LED (light-emitting

diode) technology, which became the standard for

calculator display, was not yet advanced enough to

use. So Kilby invented a new thermal printer with a

low-power printing head, that pressed the paper

readout against a heated digit.

Figure9 The First Electronic Handheld Calculator,

invented at Texas Instruments in 1967 by Jack Kilby,

Jerry Merryman, and James Van Tassel (Courtesy of

Texas Instruments)

Terminology:

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 the purposes of construction and commerce.

Circuits meeting this definition can be

constructed using many different technologies,

including thin-film transistors, thick-film

technologies, or hybrid integrated circuits. However,

in general usage integrated circuit has come to refer to

the single-piece circuit construction originally known

as a monolithic integrated circuit

Arguably, the first examples of integrated

circuits would include the Loewe 3NF. Although far

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from a monolithic construction, it certainly meets the

definition given above.

Designing:

The cost of designing and developing a

complex integrated circuit is quite high, normally in

the multiple tens of millions of dollars.This only

makes economic sense if production volume is high,

so the non-recurring engineering (NRE) costs are

spread across typically millions of production units.

Modern semiconductor chips have billions of

components, and are 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 a design flow that engineers use to design

and analyze entire semiconductor chips.

Types of Integrated Circuits:

There are different types of ICs; classification of

Integrated Circuits is done based on various criteria. A

few types of ICs in a system are shown in the below

figure with their names in a tree format.

Figure10 Different Types of ICs

Based on the intended application, the IC are

classified as analog integrated circuits, digital

integrated circuits and mixed integrated circuits.

1. Digital Integrated Circuits

The integrated circuits that operate only at a

few defined levels instead of operating over all levels

of signal amplitude are called as Digital ICs and these

are designed by using multiple number of digital logic

gates, multiplexers, flip flops and other electronic

components of circuits.These logic gates work with

binary input data or digital input data, such as 0 (low

or false or logic 0) and 1 (high or true or logic 1).

Figure11 Digital Integrated Circuits

The above figure shows the steps involved in

designing a typical digital integrated circuits. These

digital ICs are frequently used in the computers,

microprocessors, digital signal processors, computer

networks and frequency counters. There are different

types of digital ICs or types of digital integrated

circuits, such as programmable ICs, memory chips,

logic ICs, power management ICs and interface ICs..

2. Analog Integrated Circuits

The integrated circuits that operate over a

continuous range of signal are called as Analog ICs.

These are subdivided as linear Integrated Circuits

(Linear ICs) and Radio Frequency Integrated Circuits

(RF ICs). In fact, the relationship between the voltage

and current maybe nonlinear in some cases over a long

range of the continuous analog signal.

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Figure12 Analog Integrated Circuits

The frequently used analog IC is an

operational amplifier or simply called as an op-amp,

similar to the differential amplifier, but possesses a

very high voltage gain. It consists of very less number

of transistors compared to the digital ICs, and, for

developing analog application specific integrated

circuits (analog ASICs), computerized simulation

tools are used.

3. Mixed Integrated Circuits

The integrated circuits that are obtained by

the combination of analog and digital ICs on a single

chip are called as Mixed ICs. These ICs functions as

Digital to Analog converters, Analog to Digital

converters (D/A and A/D converters) and clock/timing

ICs. The circuit depicted in the above figure is an

example of mixed integrated circuit which is a

photograph of the 8 to 18 GHz self-healing radar

receiver.

Figure13 Mixed Integrated Circuits

This mixed-signal Systems-on-a-chip is a

result of advances in the integration technology, which

enabled to integrate digital, multiple analog and RF

functions on a single chip.

General types of integrated circuits (ICs) include

the following:

1. Logic Circuits:

Figure14 Logic Circuits

These ICs are designed using logic gates-that

work with binary input and output (0 or 1). These are

mostly used as decision makers. Based on the logic or

truth table of the logic gates, all the logic gates

connected in the IC give an output based on the circuit

connected inside the IC- such that this output is used

for performing a specific intended task. A few logic

ICs are shown above.

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2. Comparators:

Figure15 Comparators

The comparator ICs are used as comparators

for comparing the inputs and then to produce an output

based on the ICs’ comparison.

3. Switching ICs

Figure16 Switching ICs

Switches or Switching ICs are designed by

using the transistors and are used for performing the

switching operations. The above figure is an example

showing an SPDT IC switch.

4. Audio amplifiers

Figure17 Audio amplifiers

The audio amplifiers are one of the many

types of ICs, which are used for the amplification of

the audio. These are generally used in the audio

speakers, television circuits, and so on. The above

circuit shows the low- voltage audio amplifier IC.

5. Operational amplifiers

Figure18 Operational amplifiers

The operational amplifiers are frequently

used ICs, similar to the audio amplifiers which are

used for the audio amplification. These op-amps are

used for the amplification purpose, and these ICs work

similar to the transistor amplifier circuits. The pin

configuration of the 741 op-amp IC is shown in the

above figure.

6. Timer ICs

Figure19 Timer ICs

Timers are special purpose integrated circuits

used for the purpose of counting and to keep a track of

time in intended applications. The block diagram of

the internal circuit of the LM555 timer IC is shown in

the above circuit.

Based on the method or techniques used in

manufacturing them, types of ICs can be divided

into three classes:

1. Thin and thick film ICs

2. Monolithic ICs

3. Hybrid or multichip ICs

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Below is the simple explanation of different

types of ICs as mentioned above.

1. Thin and Thick ICs:

In thin or thick film ICs, passive components

such as resistors, capacitors are integrated but the

diodes and transistors are connected as separate

components to form a single and a complete circuit.

Thin and thick ICs that are produced commercially are

merely the combination of integrated and discrete

(separate) components.

Thick and thin ICs have similar

characteristics, similar appearance except the method

of film deposition. Method of deposition of films

distinguished Thin ICs from Thick ICs.

Figure20 Hybrid or multi chip IC

Thin film ICs are made by depositing films of

a conducting material on a glass surface or on a

ceramic base. By varying the thickness of the films

deposited on the materials having different resistivity,

Passive electronic components like resistors and

capacitors can be manufactured.

In Thick film ICs, silk printing technique is

used to create the desired pattern of the circuit on a

ceramic substrate. Thick-film ICs are sometimes

referred to as printed thin-film.

The screens are actually made of fine

stainless steel wire mesh and the links (connections)

are pastes having conductive, resistive or dielectric

properties. The circuits are fired in a furnace at a high

temperature so as to fuse the films to the substrate after

printing.

2. Monolithic ICs

In monolithic ICs, the discrete components,

the active and the passive and also the

interconnections between then are formed on a silicon

chip. The word monolithic is actually derived from

two Greek words “mono” meaning one or single and

Lithos meaning stone. Thus monolithic circuit is a

circuit that is built into a single crystal

Figure21 Monolithic IC in Plastic Package

Monolithic ICs are the most common types

ICs in use today. Its cost of production is cheap and is

reliable. Commercially manufactured ICs are used as

amplifiers, voltage regulators, in AM receivers, and in

computer circuits. However, despite all these

advantages and vast fields of application of monolithic

ICs, it has limitations. The insulation between the

components of monolithic ICs is poor. It also have low

power rating, fabrication of insulators is not that

possible and so many other factors.

3. Hybrid or Multi chip ICs

As the name implies, “Multi”, more than one

individual chips are interconnected. The active

components that are contained in this kind of ICs are

diffused transistors or diodes. The passive components

are the diffused resistors or capacitors on

a single chip.

Figure22 Hybrid or multi chip IC's

These components are connected by metalized

patterns. Hybrid ICs are widely used for high power-

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amplifier applications from 5W to more than 50W. Its

performance is better than that of monolithic ICs.

Fabrication of IC:

Figure23 Fabrication of IC's

Step1: Wafer production

Figure24 Wafer Production

The first step is wafer production. The wafer

is a round slice of semiconductor material such as

silicon. Silicon is preferred due to its characteristics. It

is more suitable for manufacturing IC. It is the base or

substrate for entire chip. First purified polycrystalline

silicon is created from the sand. Then it is heated to

produce molten liquid. A small piece of solid silicon

is dipped on the molten liquid. Then the solid silicon

(seed) is slowly pulled from the melt. The liquid cools

to form single crystal ingot. A thin round wafer of

silicon is cut using wafer slicer. Wafer slicer is a

precise cutting machine and each slice having

thickness about .01 to .025 inches. When wafer is

sliced, the surface will be damaged. It can be

smoothening by polishing. After polishing the wafer,

it must thoroughly clean and dried. The wafers are

cleaned using high purity low particle chemicals .The

silicon wafers are exposed to ultra pure oxygen.

Step2: Epitaxial growth:

Figure25 Epitaxial growth

It means the growing of single silicon crystal

upon original silicon substrate. A uniform layer of

silicon dioxide is formed on the surface of wafer.

Step3: Masking

Figure26 Masking

To protect some area of wafer when working

on another area, a process called photolithography is

used. The process of photolithography includes

masking with a photographic mask and photo etching.

A photoresist film is applied on the wafer. The wafer

is aligned to a mask using photo aligner. Then it is

exposed to ultraviolet light through mask. Before that

the wafer must be aligned with the mask. Generally,

there are automatic tools for alignment purpose.

Step4: Etching

Figure27 Etching

It removes material selectively from the

surface of wafer to create patterns. The pattern is

defined by etching mask. The parts of material are

protected by this etching mask. Either wet (chemical)

or dry (physical) etching can be used to remove the

unmasked material. To perform etching in all

directions at same time, isotropic etching will be used.

Anisotropic etching is faster in one direction. Wet

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etching is isotropic, but the etching time control is

difficult. Wet etching uses liquid solvents for

removing materials. It is not suited to transfer pattern

with submicron feature size. It does not damage the

material. Dry etching uses gases to remove materials.

It is strongly anisotropic. But it is less selective. It is

suited to transfer pattern having small size. The

remaining photoresist is finally removed using

additional chemicals or plasma. Then the wafer is

inspected to make sure that the image is transferred

from mask to the top layer of wafer.

Step5: Doping

To alter the electrical character of silicon,

atom with one less electron than silicon such as boron

and atom with one electron greater than silicon such as

phosphorus are introduced into the area. The P-type

(boron) and N-type (phosphorous) are created to

reflect their conducting characteristics. Diffusion is

defined as the movement of impurity atoms in

semiconductor material at high temperature.

Step6: Atomic diffusion:

In this method p and n regions are created by

adding dopants into the wafer. The wafers are placed

in an oven which is made up of quartz and it is

surrounded with heating elements. Then the wafers are

heated at a temperature of about 1500-2200°F. The

inert gas carries the dopant chemical. The dopant and

gas is passed through the wafers and finally the dopant

will get deposited on the wafer. This method can only

be used for large areas. For small areas it will be

difficult and it may not be accurate.

Step7: Ion implantation:

Figure28 Ion implantation

This is also a method used for adding

dopants. In this method, dopant gas such as phosphine

or boron trichloride will be ionized first. Then it

provides a beam of high energy dopant ions to the

specified regions of wafer. It will penetrate the wafer.

The depth of the penetration depends on the energy of

the beam. By altering the beam energy, it is possible

to control the depth of penetration of dopants into the

wafer. The beam current and time of exposure is used

to control the amount of dopant. This method is slower

than atomic diffusion process. It does not require

masking and this process is very precise. First it points

the wafer that where it is needed and shoot the dopants

to the place where it is required.

Step8: Metallization:

Figure29 Metallization

It is used to create contact with silicon and to

make interconnections on chip. A thin layer of

aluminum is deposited over the whole wafer.

Aluminum is selected because it is a good conductor,

has good mechanical bond with silicon, forms low

resistance contact and it can be applied and patterned

with single deposition and etching process.

Step9: Making successive layers:

Figure30 Making successive layer

The process such as masking, etching, doping

will be repeated for each successive layers until all

integrated chips are completed. Between the

components, silicon dioxide is used as insulator. This

process is called chemical vapor deposition. To make

contact pads, aluminum is deposited. The fabrication

includes more than three layers separated by dielectric

layers. For electrical and physical isolation a layer of

solid dielectric is surrounded in each component

which provides isolation. It is possible to fabricate

PNP and NPN transistor in the same silicon

substrate. To avoid damage and contamination of

circuit, final dielectric layer (passivation) is deposited.

After that, the individual IC will be tested for electrical

function. Check the functionality of each chip on

wafer. Those chips are not passed in the test will be

rejected.

Step10: Assembly and packaging:

Each of the wafers contains hundreds of

chips. These chips are separated and packaged by a

method called scribing and cleaving. The wafer is

similar to a piece of glass. A diamond saw cut the

12

wafer into single chips. The diamond tipped tool is

used to cut the lines through the rectangular grid which

separates the individual chips. The chips that are failed

in electrical test are discarded. Before packaging,

remaining chips are observed under microscope. The

good chip is then mounted into a package. Thin wire

is connected using ultrasonic bonding. It is then

encapsulated for protection. Before delivered to

customer, the chip is tested again. There are three

configurations available for packaging. They are metal

can package, ceramic flat package and dual in line

package. For military applications, the chip is

assembled in ceramic packages. The complete

integrated circuits are sealed in anti-static plastic bags.

Key features:

Equips the IC designer with the knowledge to

effectively search for and interpret prior art

Explains technical contents of semiconductor

and IC design in an interesting and non-

technical manner making it valuable as well

to IP practitioners

Addresses the legal knowledge needed by IC

inventors to avoid the risk of IP infringement

litigation

Illustrates concepts through case studies and

examples and includes crucial and valuable

search links

Covers IC design protection focusing on the

markets of the USA, UK, EC, and Asia

Pacific

Generation of IC:

Sr.

No.

Level of integration Number of active

devices per chip

1. Small Scale

Integration (SSI).

Less than 100

2. Medium Scale

Integration (MSI).

100-10,000

3. Large Scale

Integration (LSI).

1,000-100,000

4. Very Large Scale

Integration (VLSI).

Over 100,000

5. Ultra Large Scale

Integration (ULSI).

Over 1 million

1. SSI:

The first integrated circuits contained only a

few transistors(less than 100 components about 10

gates). Called "small-scale integration" (SSI), digital

circuits containing transistors numbering in the tens

provided a few logic gates for example, while early

linear ICs such as the Plessey SL201 or the Philips

TAA320 had as few as two transistors.

SSI circuits were crucial to early aerospace

projects, and aerospace projects helped inspire

development of the technology. 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. The

Minuteman missile program and various other Navy

programs accounted for the total $4 million integrated

circuit market in 1962, and by 1968, U.S. Government

space and defense spending still accounted for 37% of

the $312 million total production. The demand by the

U.S. Government supported the nascent integrated

circuit market until costs fell enough to allow firms to

penetrate the industrial and eventually the consumer

markets. The average price per integrated circuit

dropped from $50.00 in 1962 to $2.33 in 1968.

Integrated circuits began to appear in consumer

products by the turn of the decade, a typical

application being FM inter-carrier sound processing in

television receivers.

2. MSI:

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). It

contains less than 500 components or have more than

10 but less than 100 gates.

3. LSI:

Here number of components is between 500

and 300000 or have more than 100 gates.

4. VLSI:

The final step in the development process,

starting in the 1980s and continuing through the

present, was "very large-scale integration" (VLSI).

13

The development started with hundreds of thousands

of transistors in the early 1980s, and continues beyond

several billion transistors as of 2009.

Multiple developments were required to

achieve this increased density. Manufacturers moved

to smaller design rules and cleaner fabrication

facilities, so that they could make chips with more

transistors and maintain adequate yield. The path of

process improvements was 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.

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.

It contain more than 300000 component per

chip.

5. ULSI

It contains more than 1500000 components per

chip.

Advantages of IC:

1. Cost reduction due to batch processing

2. Improved functional performance

3. Increases system reliability due to the

elimination of soldered joints.

4. Matched devices.

5. Miniaturization and hence increased

equipment density

6. The entire physical size of IC is extremely

small than that of discrete circuit.

7. The weight of an IC is very less as compared

entire discrete circuits.

8. Because of their smaller size it has lower

power consumption.

9. It can easily replace but it can hardly repair,

in case of failure.

10. Because of an absence of parasitic and

capacitance effect it has increased operating

speed.

11. Temperature differences between

components of a circuit are small.

12. It has suitable for small signal operation.

13. The reduction in power consumption is

achieved due to extremely small size of IC.

Disadvantages of IC:

1. In an IC the various components are part of a

small semiconductor chip and the individual

component or components cannot be

removed or replaced, therefore, if any

component in an IC fails, the whole IC has to

be replaced by a new one.

2. Coils or indicators cannot be fabricated.

3. It can be handle only limited amount of

power.

4. High grade P-N-P assembly is not possible.

5. It is difficult to be achieved low temperature

coefficient.

6. The power dissipation is limited to 10 watts.

7. Low noise and high voltage operation are not

easily obtained.

8. Inductors and transformers are needed

connecting to exterior to the semiconductor

chip as it is not possible to fabricate inductor

and transformers on the semiconductor chip

surface.

9. Inductors cannot be fabricated directly.

10. Low noise and high voltage operation are not

easily obtained.

11. Quite delicate in handling as these cannot

withstand rough handling or excessive heat.

Uses of IC’s:

IC's are of Linear, digital and mixed types. Linear

IC's also known as analog Integrated circuits are

used in:

Power amplifiers

Small-signal amplifiers

Operational amplifiers

Microwave amplifiers

RF and IF amplifiers

Voltage comparators

Multipliers

Radio receivers

Voltage regulators

Digital IC's are mostly used in computers. They are

also referred as switching circuits because their

input and output voltages are limited to two levels

- high and low i.e. binary. They include:

Flip-flops

Logic gates

Timers

Counters

Multiplexers

14

Calculator chips

Memory chips

Clock chips

Microprocessors

Microcontrollers

Temperature sensors

Applications:

Applications for integrated circuits are as

varied as the imagination of the designers. Within

limits, anything that can be designed and built with

discrete components can be put into an IC. Audio

amplifier, video processors, logic, memory, switches,

radio frequency encoders and decoders are just a few

examples. The range of IC applications is vast and

growing daily. One of the major applications is

computing. Computers that once had thousands of

transistors have been reduced to a handful of ICs. The

early computers that were the size of a building are

now outperformed in almost every way by laptops and

even handheld computers because of the use if ICs

The applications of a ICs includes the following:

Power amplifiers

Small-signal amplifiers

Operational amplifiers

Microwave amplifiers

RF and IF amplifiers

Voltage comparators

Multipliers

Radio receivers

Voltage regulators

Radar

Wristwatches

Televisions

Juice Makers

PC

Video Processors

Audio Amplifiers

Memory Devices

Logic Devices

Radio Frequency Encoders and

Decoders

Reference Links:

http://www.tech-faq.com/integrated-circuit.html

https://anysilicon.com/history-integrated-circuit/

http://www.circuitstoday.com/integrated-circuits

http://www.answers.com

www.tech-faq.com/integrated-circuit.html

https://www.daenotes.com/electronics/devices-

circuits/integrated-circuits-ic

http://history-

computer.com/ModernComputer/Basis/IC.html

http://earthsky.org/human-world/this-date-in-science-

microchip-patent

https://www.pcworld.com/article/2048664/the-

legend-of-jack-kilby-55-years-of-the-integrated-

circuit.html

https://ethw.org/Integrated_Circuits

https://www.elprocus.com/how-integrated-circuits-

work-physically/

https://www.elprocus.com/different-types-of-

integrated-circuits/

https://www.mepits.com/tutorial/384/vlsi/steps-for-

ic-manufacturing

https://www.edgefx.in/understanding-cmos-

fabrication-technology/

Premlila Vithaldas Polytechnic

S. N. D. T. WOMEN’S UNIVERSITY

Sir Vithaldas Vidyavihar, Juhu Road

Santacruz (W), Mumbai- 400 049

Tel. +91-22-2660-8676, +91-22-2660-7668 (Fax).

e-mail: office@pvp.sndt.ac.in

Website: www.pvpsndt.org