ABSTRACT
Integrated circuit (IC) fabrication consists of a sequence of processing steps referred to as unit-step processes
that lead to the devices present on today’s microchips. These unit-step processes provide the methodology for
introducing and transporting dopants to change the conductivity of the semiconductor substrate, growing
thermal oxides for inter-and intra-level isolation, depositing insulating and conducting films, and patterning
and etching the various layers in formation of the IC. Many of these unit steps have remained essentially the
same since discrete component processing. However, others have originated and grown with the evolution of
integrated circuits from large-scale integration (LSI) with thousands of components per chip in the late 1970s
through to the ultra-large-scale integration (ULSI) era of today, with billions of devices per chip. As
technology continues to evolve into the nanometer regime, further modification of current unit-step processes
will be required. In this section, the unit-step processes for silicon IC processing as they exist today are
presented, with an eye toward the future. How they are combined to form the actual IC process will be
discussed in a later section. Because of space limitations, only silicon processes will be discussed. This is not a
major limitation, as many of the same steps are used to process other types of semiconductors, and perhaps
more than 98% of all ICs today and in the near future are and will be made of silicon. Furthermore, only the
highlights of the unit steps can be presented in this space, but ample references are provided for a more
thorough presentation. The referenced processing textbooks provide a detailed discussion of all processes.
