In this tutorial, we are going to learn about IC (Integrated circuit).
IC (Integrated circuit)
The circuit in which circuit components like transistors, diodes, resistors is combined together to perform a 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