HOW IT'S MADE: CPU
Technology in recent years has shown much progress. The CPU is but an excellent example of this creative power of technology. To know all about the mechanics of it, all you need is to check out this video.
The insides of CPUs exhibit a whole range of these transistors clubbed together in a fashion that enables them to perform several functions. There are step-by-step processes involved in manufacturing a CPU! Have you wondered how it’s all made?
So, welcome back to How It’s Made and today we are going to show you all the years of engineering that have been put together to make such a masterpiece of computer processors!
Step 1: Sand In The Making Of CPU
Have you ever imagined sand to have any role in the making of your CPU? Sounds odd but this has been one of the principal elements involved in manufacturing such a wonderful thing!
Silicon is an essential chemical element that is required to produce microchips. Since sand contains high levels of silicon, the same is needed for making the microprocessors. Silicon, specifically, silicon dioxide is the foundation ingredient involved in the entire process of manufacturing semiconductors.
The sand in its original form cannot be used for manufacturing semiconductors. The process involved in extracting silicon out of it is called purification whereby the sand has to be heated using Carbon, which acts as a reducing agent in the whole process. The heating separates Carbon Monoxide and Silicon from the sand.
Step 2: The Formation and Slicing of the Ingot
The silicon extracted by heating and purifying sand reaches a polycrystalline state in which it gains certain qualities specific to creating a semiconductor. The silicon in this phase is termed Electronic Grade Silicon.
The Electronic Grade Silicon produced is further utilized for the creation of single-crystal silicon, called Ingot. This ingot is what is used for the manufacturing of chips.
Also known as boule, the Ingot is monocrystalline silicon that appears in a salami-shape bar of silicon. The ingot has a high level of purity with less than .1% of impurities. The ingot produced is ultimately converted to wafers.
The process involved here is slicing. Slicing is done with the help of super speed saws. The ingots are placed under these saws which divide them into thin disc-shaped wafers. Each wafer resembles a dime-like thickness.
Step 3: Wafer Polishing
The wafers produced have uneven surfaces which can lead to several damages. The polishing of wafers thus becomes important. The process involved in polishing wafers is a chemical process, termed Chemical Mechanical Processing.
The Polished wafers exhibit a mirror-like smooth finish, free of any type of unevenness. Polishing also makes the wafers free of unwanted particles that otherwise contaminate it. The result is you get a better quality wafer.
Dicing becomes an easy job once the wafer is free of all uneven subsurfaces. Hence, polishing is necessary.
Step 4: Wafers Are Exposed To UV Light
Exposure to UV light is directly responsible for creating Integrated Circuits as well as computer chips. UV light exposure creates geometric patterns on the surface of the semiconductor wafers and thereby, makes its soluble.
Before exposing the wafers to UV light, they are made to come in contact with a blue liquid which is photo-resisting. As the wafer is spun at high speed, the blue liquid is gradually poured over it in a way that an even layer of the coat covers the whole surface of the wafer.
A third thing involved in this process is a stencil-like substance, called a photomask which has to be aligned with the wafer. The mask contains a lens that is placed in a middle position between the wafer and the mask.
Step 5: Photo Resist Washing And Etching Of The Wafer
While the exposure to UV light makes the material of the silicon wafer soluble, the same is washed off using a chemical solvent. This process is essential to make visible the geometric patterns created on the surface of the silicon wafer.
Once washing is done, the next essential step that is involved in making the CPU is etching. In the case of microfabrication, etching is the process that causes the removal of layers, by dissolving the substrate parts from the surface of the wafers.
Etching is a chemical process done with the help of a chemical solvent. It is a critically unavoidable process. Every wafer is subjected to several steps of etching before they are ready for use.
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