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Semiconductor manufacturing and fabrication is
the process industry uses to create an integrated circuit for
use in electronic devices. The steps required to create a
semiconductor are chemical and photographic techniques to
create what is termed a wafer. The wafer may be composed of
semiconductor material, such as Silicon (made primarily from
sand), gallium arsenide, germanium and other materials.
When a wafer is made from purified silicon, it
is grown from crystalline ingots using the Czochralski
process. After the wafers have been grown into a cylinder,
they are cut to create an optimal thin flat shape (thin and
circular). On the cut wafer piece, many more steps are
employed to create a final product. A typical first step may
be that a p-type (epi-layer) layer is grown on the cut wafer
(silicon substrate) by a process called chemical vapor
deposition. The next layer may be nitride, then the silicon
substrate is masked and etched as required to expose areas on
p-type layer. These etched areas are then masked again, then
processed by diffusion or ion implantation to create dopants
such as phosphorus to form n-wells.
The Ion implantation require equipment that
consists of a controlled and directed ion source, where the
ions are electrostatically accelerated by a high energy which
are then directed onto the substrate. Where the ions are
targeted on the substrate, the ion implantation cause a
chemical change on the substrate surface. Following this step,
many more layers and masking steps may be utilized to
ultimately create many multilayer integrated circuits on the
same circular wafer. Following testing, each integrated
circuit is cut from the wafer using a precision diamond saw.
Each integrated circuit is assembled into a protective and
final package. The final semiconductor integrates circuit, is
then tested again to verify performance.
The steps outlined are one of many possible
processes used within industry for manufacturing a
semiconductor. In reality, there may be more than 250 very
high technology steps required to manufacture a semiconductor.
Other processes used in semiconductor
manufacturing are:
Terms defined:
Etch - Process used to remove selected
portions of material from the wafer.
Ions - Atoms which have an electrical charge.
The ions cause the required chemicals changes on the surface
of the wafer.
Masks - Masks are used on wafers and printed
circuit boards on selected areas to prevent material removal
from subsequent manufacturing processes.
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