The level of integration. The last several decades

The first transistor was developed by John Bardeen, Walter Brattain and
William Shockley at Bell laboratories in 1947 enabled the rapid growth of the semiconductor
technology industry. The first integrated circuits of seventies available in
market had a few hundreds
transistors which were manufactured in bipolar technology 29. Bipolar transistors can be either of NPN or
PNP silicon structure. In these bipolar transistors, small current into very
thin base layer controls large currents between emitter and collector. Base
currents limit significantly affected the integration density of bipolar
devices 29. Bipolar technology delivered high current drive, high performance,
high switching speed, smaller propagation delay, but high power consumption
makes very large scale integration difficult.



Following bipolar
junction transistor technology, comes the MOSFET (Metal-Oxide-Semiconductor
Field Effect Transistor) with very interesting feature of low power
consumption, low operating voltage, higher speed etc. which make MOSFET useful
in electronics design 20. Two types of MOS transistor PMOS and NMOS are used
for designing integrated circuits. Both types have very high static power consumption.

This problem is overcome by the logic designed in such a way that it consumes
low power in static state. Frank Wanlass introduces a new logic designed using
two complementary p-type and n-type MOSFETs. Two main advantages of CMOS
technology have high noise immunity and very low static power consumption. Since MOSFET consume very low power, it allows a higher level of
integration. The last several decades have seen innovation of new CMOS
technologies with excellent features. The trends of MOS integrated circuits
downsizing is as given below 20:


(2D technology from 1970) 10?m -> 8?m -> 6?m ->
4?m -> 3?m -> 2?m -> 1.2?m -> 0.8?m -> 0.5?m -> 0.35?m -> 0.25?m
-> 180nm -> 130nm -> 90nm-> 65nm -> 45nm  -> 32nm  -> 28nm

(3D technology) -> 22nm (2011) -> 15nm (2013) ->
10nm (2015) -> 7nm (2017)