02-02-2012, 12:24 PM
Fabrication of P-N JUNCTION DIODE
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BASIC SEMICONDUCTOR
1.1 Semiconductor:-
A semiconductor is a material that has an electrical conductivity between that of a conductor and an insulator. Conductors have very low resistivity (10-2 to 10-8 Ωm) insulator have very high resistivity (>10-2 Ωm), while semiconductors have intermediate values. Semiconductor has resistivity values of order 105 to 100 Ωm.
A semiconductor, such as silicon, has properties somewhere between those of a conductor and an insulator. The ability of a semiconductor to conduct electricity can be changed dramatically by adding small numbers of a different element to the semiconductor crystal. This process is called doping.
Devices made from semiconductor material form the basis of electronics devices like radio, TV, computer, mobile.
IC- FABRICATION TECHNOLOGY
2.1 Introduction:-
To realize Semiconductor devices or an integrated circuit an adequate set of technological steps is required that allows the realization of the same on top surface of a semiconductor wafer.
IC fabrication technology is the process used to create the integrated circuits (silicon chips) that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photographic and chemical processing steps during which electronic circuits are gradually created on a wafer made of pure semiconducting material.
. FABRICATION OF SILICON P-N JUNCTION DIODE
3.1 Introduction:-
The P-N junction is formed from a single mono crystalline structure by adding carefully controlled amounts of donor and acceptor impurities. The first and foremost requirement is to obtain an extremely pure germanium or silicon. Impurity of less than one part in ten billion (1010) is required for most semiconductor device fabrication to-day.
3.2 Wafer Specification:-
A typical wafer is made out of extremely pure silicon that is grown into mono-crystalline.
