Build A CPU

When companies like Intel and AMD decide to make CPUs, the ultimate puzzle for them is how to organize something with 1,000,000,000 pieces, and then create a plan so it can be put together correctly and at once. Most CPUs, both commercial and professional, are smaller than half of a credit card size. The only way to solve this problem is to use chemistry. The process of making CPU is called fabrication. The structure of CPU is so complex that even a single dust could ruin the complex circuitry on a chip.

The main component of chips is silicon, and sand has a high percentage of silicon. First silicon is purified to less than one alien atom per billion. The most common way of doing this is to first transform sand to metallurgical grade silicon by using the following reaction: SiO2 + C = Si + CO2 Then, scientists will transfer metallurgical grade silicon to electronic grade, which has less number of alien atoms. They use Si + 3HCl = SiHCl3 + H2. During this reaction, the impurities such as Fe, Al, and B will react with HCl and form other substances. the SiHCl3 has a low boiling point of 31.8 C and distillation is used to purify the SiHCl3 from the impure halides. At last, SiHCl3 will react with hydrogen at 1100 C for 200 ~300 hours to produce a very pure form of silicon.

After pure silicon is produced, they will cut the silicon ingot into individual discs that are called wafers. Each wafer is about one mm thick. After that, the photolithography process begins. Most of the photolithography is based on Diazoquinones (DQ). There are few steps to finish the photolithography process. Start with a DQ molecule (the molecule is a manufacturer variation), The DQ molecule will not dissolve in a base developer solution. UV light breaks the nitrogen molecule off, forming an unstable molecule. To stabilize itself, one of the carbon atoms in the ring pops out of the ring. Once the solution is exposed to water, an OH group attaches to the carbon atoms, forming and acid. The Acid can then react and dissolve with the basic developer solution. In this way, the manufacturer can “print” circuit patterns on the wafer. The manufacturer will repeat this procedure again and again until they have a multilayer processor. They will also use this method to print other parts and gates on the processor.