Page 19 - Microsensors, MEMS and Smart Devices - Gardner Varadhan and Awadelkarim

Introduction

1.1 HISTORICAL DEVELOPMENT OF
MICROELECTRONICS

The field of microelectronics began in 1948 when the first transistor was invented.
This first transistor was a point-contact transistor, which became obsolete in the 1950s
following the development of the bipolar junction transistor (BJT). The first modern-
day junction field-effect transistor (JFET) was proposed by Shockley (1952). These two
types of electronic devices are at the heart of all microelectronic components, but it
was the development of integrated circuits (ICs) in 1958 that spawned today's computer
industry.
1C technology has developed rapidly during the past 40 years; an overview of the
current bipolar and field-effect processes can be found in Chapter 4. The continual
improvement in silicon processing has resulted in a decreasing device size; currently,
the minimum feature size is about 200 nm. The resultant increase in the number of
transistors contained within a single 1C follows what is commonly referred to as Moore's
law. Figure 1.1 shows that in just 30 years the number of transistors in an 1C has risen
from about 100 in 1970 to 100 million in 2000. This is equivalent to a doubling of
the number per chip every 18 months. Figure 1.1 plots a number of different common
microprocessor chips on the graph and shows the clock speed rising from 100 kHz to
1000 MHz as the chip size falls. These microprocessors are of the type used in common
1
personal computers costing about €1000 in today's prices .
Memory chips consist of transistors and capacitors; therefore, the size of dynamic
random access memories (DRAM) has also followed Moore's law as a function of time.
Figure 1.2 shows the increase of a standard memory chip from 1 kB in 1970 to 512 MB
in 2000. If this current rate of progress is maintained, it would be possible to buy for
€1000 a memory chip that has the same capacity as the human brain by 2030 and a
memory chip that has the same brain capacity as everyone in the whole world combined
by 2075! This phenomenal rise in the processing speed and power of chips has resulted
first in a computer revolution and currently in an information revolution. Consequently,
the world market value of ICs is currently worth some 250 billion euros, that is, about
250 times their processing speed in hertz.

1 euro (€) is currently worth about 1 US dollar.