Page 446 - Solid Waste Analysis and Minimization a Systems Approach

424 ELECTRONICS, SEMICONDUCTORS, AND OTHER ELECTRICAL EQUIPMENT

subsector. Digitalization of sound recording, for example, causes both the medium (the
compact disc) and the equipment to resemble the technologies for recording, storing,
transmitting, and manipulating data. Communications technology and equipment have
been converging with computer technology. When technologically related components
are in the same sector, it makes it easier to adjust the classification for future changes,
without needing to redefine its basic structure. The creation of the computer and elec-
tronic product manufacturing subsector will assist in delineating new and emerging
industries because the activities that will serve as the probable sources of new industries,
such as computer manufacturing and communications-equipment manufacturing, or
computers and audio equipment, are brought together. As new activities emerge, they are
less likely therefore, to cross the subsector boundaries of the classification.
Semiconductors are electrical devices that perform functions such as processing
and display, power handling, and conversion between light and electrical energy.
Semiconductor production processes involve over 100 proprietary solutions and 200
generic materials to achieve the final product. This industry generates significant
quantities of spent solvents and liquids containing metals. The economic and liability
incentives caused by increasing disposal costs and more stringent regulations are
resulting in efforts to minimize such wastes at the source.
Semiconductors are unique substances, which, under different conditions, can act as
either conductors or insulators of electricity. Semiconductor processors turn one
of these substances—silicon—into microchips, also known as integrated circuits.
These microchips contain millions of tiny electronic components and are used in a
wide range of products, from personal computers and cellular telephones to airplanes
and missile-guidance systems.
To manufacture microchips, semiconductor processors start with cylinders of sili-
con called ingots. First, the ingots are sliced into thin wafers. Using automated equip-
ment, workers or robots polish the wafers, imprint precise microscopic patterns of the
circuitry onto them using photolithography, etch out patterns with acids, and replace
the patterns with conductors, such as aluminum or copper. The wafers then receive a
chemical bath to make them smooth, and the imprint process begins again on a new
layer with the next pattern. A complex chip may contain more than 20 layers of cir-
cuitry. Once the process is complete, wafers are then cut into individual chips, which
are enclosed in a casing and shipped to equipment manufacturers.
The manufacturing and slicing of wafers to create semiconductors takes place in
clean rooms—production areas that are kept free of all airborne matter because the cir-
cuitry on a chip is so small that even microscopic particles can make it unusable. All
semiconductor processors working in clean rooms must wear special lightweight outer
garments known as “bunny suits.” These garments fit over clothing to prevent lint and
other particles from contaminating the clean room.
There are two types of semiconductor processors: operators and technicians.
Operators start and monitor the equipment that performs the various production tasks.
They spend the majority of their time at computer terminals, monitoring the operation
of equipment to ensure that each of the tasks in the production of the wafer is performed
correctly. Operators may also transfer wafer carriers from one station to the next, though
the lifting of heavy wafer carriers is done by robots in most new fabricating plants.