Integrated Circuits (ICs)

(Microcircuits or Chips)

Integrated circuits are electronic circuits in micro- miniature size, existing on a single piece of silicon, germanium, gallium arsenide, or inert material (glass or ceramic) containing up to tens of millions of transistors and other devices (diodes, resistors, capacitors). These devices are formed in the semiconductor substrate, or as part of film layers added to it. Twenty or more layers of circuitry may be involved and the devices are all permanently interconnected. Circuit elements and devices on each chip are extremely small and wiring paths are as narrow as 5 millionths of an inch (0.13 microns), or less. (Process and design improvements are continually being made. The Semiconductor Industry Association has projected circuit dimensions of 0.05 microns, 50 nanometers, or 2 millionths of an inch by 2012.) ¹² ICs are produced in mass-production quantities with extensive, highly sophisticated, extremely precise and extremely clean manufacturing processes, often involving 600 or more steps before each chip is completed. Chips vary in size but a common surface area is 0.24 sq. in (1.5 sq cm).

Integrated circuits are the brains of computers and other electronic devices including televisions, radios, stereo equipment, cellular and regular phones, instruments, control devices, military navigation equipment and firearms, aircraft, spacecraft, missiles, medical devices, digital watches, automotive diagnostic devices, traffic control, environmental monitoring, industrial process controls, video games and appliance controls.

The integrated circuit manufacturing process must deal with circuit features that have the very smallest dimensions and are subject to very subtle electrical and chemical effects. In order to prevent manufacturing defects, the entire fabrication sequence must be free from contamination by extraneous particles and chemicals. Clean room conditions, with the highest order of freedom from extraneous particles, are maintained by use of fine filters for ambient air and by limiting garments and room equipment to lint-free types. Clothing must prevent the release of contaminants from workers. Contamination from solvents and other chemicals, tools, equipment and production supplies must also be carefully controlled throughout the process.

IC manufacture includes the following major stages: material preparation, single crystal making, wafer preparation, wafer fabrication (including the incorporation of circuitry), and packaging.