In this tutorial, we are going to learn about IC (Integrated circuit).
IC (Integrated circuit) – Circuit in which circuit components like transistors, diodes, resistors is combine together to perform various function is called IC (Integrated circuit)
- It is that circuit in which the circuit components such as resistor, capacitor, diode and transistor etc are automatically parts of a small S/C chip.
- It means an integrated circuit consist of number of circuit components like – resistors, capacitors, inductors, diodes, transistor, logic gates etc. interconnection in single small package to perform a complete electronic function.
- IC made by various components which are connected within small chip of S/C (silicon) material.
- A thin slice of single crystal of silicon about 0.05 cm thick called silicon wafer.
- The wafer may have diameter range 2.5 cm to 10 cm.
- These wafers are used to make devices and IC.
- A small portion of the silicon wafer is dimension 50 mil x 50 mil.
- This small portion of the wafer is called silicon chip.
- The area required for a resistor, diode and a transistor is of dimensions (12mil x 12 mil) (4.5 mil x 3 mil) and (6.5 mil x 4 mil).
- The various circuit components such as resistor, capacitors, diode, and transistor and logic gate can be grown over such one silicon chip.
- The technology used for the fabrication of IC is quite complicated but it is becoming cheaper due to large scale.
Fabrication Steps for IC:
Below are the process are involved in the fabrication of IC.
- Lithography: It is the process for pattern definition by applying thin uniform layer of viscous liquid like photo-resist on the wafer surface.
- Etching: In this process first selectively removing unwanted material from the surface of the wafer and in this process the pattern of the photo-resist is transferred to the wafer by means of etching agents.
- Deposition: In this process the films of the various materials are applied on the wafer.
- Chemical Mechanical Polishing: It is a planarization technique which by applying a chemical slurry with etchant agents to the wafer surface.
- Oxidation: In this process oxygen it is dry oxidation) or HO it is wet oxidation which molecules convert silicon layers on top of the wafer to silicon dioxide.
- Ion Implantation: Most widely used technique to introduce do pant impurities into semiconductor. The ionized particles are accelerated through an electrical field and targeted at the semiconductor wafer.
- Diffusion: In this process a diffusion step ion implantation is used to anneal bombardment-induced lattice defects.
IC (Integrated circuit) Types:
SSI – Small Scale Integrated circuit
MSI – Medium Scale Integrated circuit
LSI – Large Scale Integrated circuit
VLSI – Very Large Scale Integrated circuit