From start to finish, it requires about 1,500 steps to make Silicon.
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Think of a semiconductor as something that can run hot and cold. Hot when conducting electricity and cold when insulating against it. After Carbon, Silicon (Si) is the second most ubiquitous material on earth. And from beach sand silicon chips are made.
It took decades to perfect the process of producing silicon with a perfect monocrystalline structure. They begin with melting in a furnace raw polysilicon. The poly is heated to over 1,371 degrees Celsius to purge the silicon of impurities.
The liquified silicon is then spun in one direction, while a silicon seed, about the size of a pen, is sent down into the molten silicon and spun in the opposite direction.
Why two directions? It saves wear and tear on the expensive equipment. The silicon doesn’t care which way it is spun. So, spinning in a crucible bi-directionally speeds the ingot creation with less burden to the system.
Once cooled the silicon crystal seed is pulled from the crucible at a very slow rate of about 90mm per hour.
The silicon crystal weight depends on the diameter of the ingot. For example a 200mm silicon crystal ingot is about 440 pounds.
Technicians then test the purity and molecular orientation. Its then sent to wire sawing. The equipment looks a giant bread-slicer. Thin wires cut the ingot into silicon wafers of silicon. The waste created by the wire saw is called Kerf. Currently some firms are working on creating silicon by simply pouring the molten Si liquid into molds. Kerfless silicon would save greatly on expense as no amount of silicon is wasted! Solar cell manufacturing firm 1366, Inc. is at the forefront of this research.
Wire cutting into individual slices damages the wafer. Several more procedures are then used to smooth the silicon surface to a flatness that can be used in Integrated Circuits (IC).
Dust is a central concern for all Silicon circuit production. So in a clean-room, that is the envy of a hospital surgery room. Only 100 particles per cubic foot of air are allowed in the cleanroom where the wafers have circuits etched onto it. One dust particle can destroy a chip.
Decades ago, only one transistor could fit on a chip. Today it’s billions!
Engineers than use the photolithography process to create the chip architecture.
The photolithography processes is repeated almost 50 time before the the chip is ready to be packaged and shipped.