The post-war period of the late 1940s saw dramatic shifts in the scientific community as the atomic age dawned. Research, innovation and invention efforts flourished. Electronics, based on vacuum tube technology, had made early radios, telephones, and televisions possible. In 1947, researchers at Bell Laboratories developed and demonstrated a solid-state transistor that improved upon, and eventually replaced, the vacuum tube. Solid-state transistors made of the common element, silicon, followed shortly thereafter.
From those humble beginnings, the semi-conductor industry exploded, achieving worldwide sales exceeding $400 billion in 2019. The manufacturing processes that produce silicon integrated circuits (ICs) have been largely automated. The initial steps include purification of mined ore, crystal ingot growth and doping with specific elements, sawing of wafers, silicon wafer polishing and etching. These steps prepare the substrate upon which microprocessor circuitry is then built.
The final steps to produce microprocessors and other ICs include very precise manipulations and modifications of the doped wafers. Central processing units used in personal computers today contain as many as 100 million transistors per square millimeter. Many of the manufacturing techniques to achieve this scale of construction are proprietary. Generally, they involve repeated layering and etching away of different materials on the substrate of the wafer. This may include lithography and deposition by exposing the surface to gases in carefully controlled environments. The entire process takes place inside a Cleanroom fabrication environment to eliminate any potential contamination.
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At some point in the process contacts and conductors are installed by depositing minute amounts of copper between circuits on the chip. These carry electrical signals to and from the chip’s transistors and circuitry as well as into and out of the chip. The CPU’s role in personal computers is primarily to carry out arithmetic and logical operations on binary data represented by different voltage levels. Peripheral circuits, external to the microprocessor, typically handle connections and the flow of data between devices like monitors, keyboards, printers and storage.
The rate at which microprocessors carry out massive numbers of operations with electrical current generates significant amounts of heat energy. Managing this heat is accomplished by encasing the finished chip in a heat-dissipating metal body. Additional heat energy dissipation requires large aluminum heat sinks and fans affixed to the processor’s metal casing.
Over the course of the last 75 years, electronic technologies have advanced dramatically. Research and development activity and precision engineering have enabled these advances. Successive improvements will doubtless continue to produce more sophisticated and powerful computing instruments to enhance and improve daily living.