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INTRODUCTION TO SEMICONDUCTOR TECHNOLOGY

2 BASIC IC ELEMENT: THE TRANSISTOR

2.1 MOS TECHNOLOGY

We will examine first the basics of MOS (Metal Oxide Semiconductor) technologies as they

are used for the majority of the integrated circuits manufactured at STMicroelectronics.

. There are three major MOS technology families: PMOS, NMOS and CMOS. They refer to the

channel type of the MOS transistors made with the technology.

– PMOS technologies implement P-channel transistors by diffusing P-type dopants (usually

Boron) into an N-type silicon substrate to form the source and the drain. P-channel is so

named because the channel is composed of positively charged carriers.

– NMOS technologies are similar, but use N-type dopants (usually Phosphorus or Arsenic)

to make N-channels transistors in P-type silicon substrate. N-channel is so named because

the channel is composed of negatively charged carriers.

– CMOS (Complementary MOS) technologies combine both P-channel and N-channel de-

vices on the same silicon. Either P or N-type silicon substrates can be used. However, deep

areas of the opposite doping type (called wells) must be defined to allow fabrication of the

complementary transistor type.

Figure 11. MOS Technologies