CPU Chip Manufacturing Process

CPU manufacturing is a complex process that has been evolving since the invention of solid state electronics. Microchips are built on a silicon base, which is treated with different chemicals, radiation and metals to form a network of atomic-scale transistors. Producing a microchip requires a large and complex infrastructure to precisely control the chemicals and temperatures required on a microscopic level. Chips are built in so-called "clean rooms," which contain practically no dust at all, and the engineers wear static, lint and dust-free body suits. If a single speck of dust lands on a bare microchip, it will be completely destroyed.

• 1

  A polysilicon base is melted together with small amounts of conductive elements such as arsenic, boron, phosphorous or antimony. The materials are melted down in a quartz container, because quartz melts at a higher temperature than silicon and the other materials.

• 2

  A device lowers a silicon crystal "seed" into the molten silicon, and the melt is slowly cooled. As the silicon cools, it crystallizes around the seed. A machine slowly removes or "pulls" the seed from the melt, which has become a small ingot of base material.

• 3

  Engineers shave off the ends and edges of the ingot, which contain the highest concentrations of impurities. An automated wire saw cuts the ingot into wafers that are only 1 to 2 millimeters thick.

• 4

  Engineers heat the wafers to remove defects and examine them with a laser to make sure that the crystal structure is pure. Machines grind and polish the wafers to turn them into very flat, thin structures, polished until they're like mirrors.

• 5

  The engineers create a pattern of different layers on the wafer using a process called photolithography. They coat the silicon with a substance called photoresist, which dissolves under ultraviolet light. The wafer is partially covered by a pattern called a "mask" and then exposed to ultraviolet light. Exposed photoresist burns away, leaving only the parts covered by the mask. The engineers repeat this process several times to create many layers of different patterns.

• 6

  Ions -- elements with abnormal numbers of electrons bombard the layers. The ions change the semiconductive properties of the silicon, turning the layers into a network of transistors.

• 7

  When all the layers are finished, engineers create openings in the chip using photolithography. These holes allow the layers to be connected to each other.

• 8

  Another machine coats the wafer with aluminum or copper atoms, which also fill in the openings. The metal creates electrical connections between the transistors.

• 9

  Engineers test every chip on the wafer and discard the faulty ones. Often the chips on the edge of the wafer are flawed, and the best ones near the center are tested further to see if they meet military or industrial specifications.

• 10

  A special cutting machine cuts the wafer into individual chips, which are then implanted in ceramic casings.