An integrated circuit, or IC, is small chip that can function as an amplifier,
oscillator, timer, microprocessor, or even computer memory. An IC is a small
wafer, usually made of silicon, that can hold anywhere from hundreds to
millions of transistors, resistors, and capacitors.
1.Just as in building a house, you need a construction plan to construct a
chip. The construction plans for the chip are made and tested with a
2.From the construction plans, masks with the circuit patterns are made.
3.Under precisely monitored conditions, a pure silicon crystal is grown.
Circuit manufacturing demands the use of crystals with an extremely high
grade of perfection.
4.The silicon is sawed into thin wafers with a diamond saw. The wafers
are then polished in a number of steps until their surface has a perfect
5.The silicon wafer is covered with a layer of insulating silicon oxide.
6.A covering film of protective material is put on top of the insulating
silicon oxide. This material, a bit like the film in any ordinary camera, is
sensitive to light.
7.UV-light is shone through a mask and onto the chip. On the parts of the
chip that are hit by light, the protective material breaks apart.
8.The wafer is developed, rinsed and baked. The development process
removes the parts of the protective material exposed to light.
9.The wafer is treated with chemicals in a process called "etching." This
removes the unprotected insulating material, creating a pattern of non-
protected silicon wafer parts surrounded by areas protected by silicon
10.The wafer is run through a process that alters the electrical
properties of the unprotected areas of the wafer. This process is called
"doping." Steps 5-10 are repeated to build the integrated circuit, layer
by layer. Other layers of conducting or isolating layers may also be
added to make the components.
11.Finally, when all the components of the chip are ready, metal is
added to connect the components to each other in a process called
metallization. This is done in a way similar to the making of the
components. First a conducting metal like copper is deposited over the
12.On top of the metal a layer of UV-sensitive photo resist is added.
13.Next, a mask that describes the desired layout of the metal wires
connecting the components of the chip is used. UV-light is shone
through this mask. The light hits the photo resist that isn't protected by
14.In the next step, chemicals are used to remove the photo resist hit by UV-
15.Another step of etching removes the metal not protected by photo resist.
16.This leaves a pattern of metal that is the same as the one described by
the mask. Now, the chip has a layer of wires that connect its different
17.Today, most integrated circuits need more than one layer of wires.
Advanced circuits may need up to five different layers of metal to form all the
necessary connections. So a layer of insulating material is put between the
two metal layers to prevent the wires from connecting in the wrong places.
18.When the final layer of connecting metal wires have been added, the
chips on the silicon wafer are tested to see if they perform as intended.
19.The chips on the wafer are separated with a diamond saw to form
individual integrated circuits.
20.Finally, each chip is packed into the protective casing and subjected to
another series of tests. The chip is now finished and ready to be shipped
to manufacturers of digital devices around the world.
Small scale integration (SSI) [ < 12 ]
Medium scale integration (MSI) [ 12 – 100 ]
Large scale integration (LSI) [100 – 1000 ]
Very Large Scale Integration (VLSI) [ > 1000 ]
Ultra Large Scale Integration (ULSI) [ > 1000000 ]
The speed of operation of an IC can be understood with the help of
Is the capacity of a single gate to drive similar gates.
CHARACTERISTICA OF ICs
Speed Of Operation
Current and voltage parameters
P.D = Voltage x Current = V x I
= (Voltage)2 / Resistance = V2R
= (Current)2 x Resistance = I2R
Figure of merit = propagation delay x power dissipation
= Nanoseconds (ns) x mW
= Pico joules (pj)
High level input voltage
This is the minimum voltage level required at an input for logic 1
Low level input voltage
This is the maximum voltage level required at an input for logic 0
High level output voltage
This is the minimum voltage level required for a logic 1 at the output
of the gate.
Low level output voltage
This is the maximum voltage level required for a logic 0 at the output
of the gate.
The ability of a circuit to tolerate the noise signals is known as noise
immunity and the term noise margins used to measure the noise immunity.
For consumer :- 00 C to 700 C
For industries :- -550 C to 1250 C
Bipolar Transistors (BJTS)
TYPES OF LOGIC FAMILIES