How to Make a CPU
Believe it or not, your CPU (or central processing unit) came from sand. More specifically, CPU’s are constructed out of the silicon that makes up about 25 percent of all sand. Silicon (found naturally in the form of silicon dioxide) is actually the second most abundant chemical element found in the Earth’s crust, the most abundant element being oxygen or O2.
Accordingly, sand must be procured in large quantities and silicon must be separated out and purified in a multi-step process. The silicon must be purified to the point that it only possesses one alien atom for every one billion silicon atoms to reach electronic grade.
Once purified, the silicon is melted down into one large crystal or mono-crystal, called an ingot. You may not have ever heard the word ingot before, but it actually dates back to 13th century Middle England, when it meant something that other things are poured into equivalent to in- + got, got being an old English word for stream, flow or pour.
Anyway, these ingots are around or over 5 feet tall and weigh in at approximately 220 pounds. Once they’ve fully formed, they are sliced into individual silicon disks called wafers. There are several ingot molds with different diameters, each to be used for different wafer sizes. Today, CPU’s are generally created on 30 mm wafers.
Once the wafers are sliced, they are each polished until they have flawless, mirror-smooth surfaces.
They are then spun as an even layer of blue, photo-resistant finish is poured over them until they are coated completely. This photo-resistant finish is also used in film for photography.
Once the coating has been added, UV light is aimed at the wafer to trigger a chemical reaction similar to that which occurs on film material in a camera when you press the shutter button i.e. the areas of the resist on the wafer that have been exposed to UV light will become soluble.
Before the UV light exposure commences, a stencil-like mask if placed on the wafer to create certain circuit patterns. This process is repeated over and over until multiple layers of circuit patterns have been stacked on top of each other.
Because the pattern to be imprinted on the wafer is tiny, a lens is placed between the mask and the wafer to reduce its image to a smaller focal point.
Once exposure has been completed, the exposed blue photo resist areas are dissolved by a solvent, revealing a pattern of photo resist made by the mask. These patterns are the foundation of transistors, interconnects, and other electrical contacts to come.
This process is repeated a number of times until the ion doping stage. This is when the wafer is exposed to particular ion particles that allow the silicon to change its chemical properties in a way that enables the forming CPU to control its flow of electricity. Ions are propelled onto the surface of a wafer using an electrical field that accelerates the ions to a speed of over 300,000 km/hr, altering the way the silicon in the targeted areas conduct electricity. These areas will have lost their silicon purity and instead contain many alien atoms.
Then the wafers are put into a copper sulphate solution. Cooper ions are deposited onto the transistor area through a process called electroplating. The copper ions then travel from the positive terminal (anode) to the negative terminal (cathode), which is represented by the wafer. The copper ions then settle in a thin layer at the surface of the wafer.
This is how just one layer of many is created among the interconnects and transistors that layer on top of one another to create a CPU