Semiconductors are essential components of modern electronics. They are made from silicon, a material that can neither conduct electricity very well nor insulate it very well, property makes it particularly effective in controlling the flow of electricity between different components which why they are a staple in the manufacturing process of electronics such as televisions, phones, and more. Thus silicon is perfect for use in transistors, which are the building blocks of electronic circuits.
Wafer Manufacturing
The first step in the semiconductor manufacturing process is to create a wafer. Silicon is extracted from sand and then purified as close to 100% purity as possible into a polysilicon form. This polysilicon is then melted down and formed into a long, cylindrical ingot. The ingot is sliced into thin wafers, which are then polished to a mirror finish. Purification and making an ingot are arguably the most important steps in silicon wafer manufacturing.
Oxidation
Once the wafers have been polished, they are subjected to a process called oxidation. In this process, a thin layer of silicon dioxide is grown on the surface of the wafer. The silicon dioxide layer acts as an insulator and helps to protect the underlying silicon.
Photolithography
Photolithography is a process that is used to create patterns on the wafer. A photosensitive material called photoresist is applied to the wafer. Then, a mask is placed on top of the photoresist and light is shone onto the wafer through the ‘reticle’, which holds the blueprint of the pattern to be printed. The light exposes the photoresist, which makes it soluble in a developer solution. The developer solution is used to remove the exposed photoresist, leaving behind a pattern on the wafer.
Etching
The next step in the process is etching. To remove the degraded resist to reveal the intended pattern. Here, the wafer is etched with a chemical or plasma that removes the material that is not protected by the photoresist. The etching process creates the desired features on the wafer, such as transistors and wires. Advanced etch technology is enabling chipmakers to use double, quadruple and spacer-based patterning to create the tiny features of the most modern chip designs. There are two types of etch: ‘wet’ and ‘dry’. Dry etching uses gases to define the exposed pattern on the wafer. Wet etching uses chemical baths to wash the wafer. Companies such as Lam Research, Oxford Instruments and SEMES develop semiconductor etching systems.
Deposition and Ion Implantation
After the wafer has been etched, the wafer may be bombarded with positive or negative ions to tune the electrical conducting properties of part of the pattern. This metal layer is used to create the wires that will connect the transistors together. Ion implantation is a process that is used to introduce impurities into the silicon. These impurities change the electrical properties of the silicon, making it more conductive.
Metal Wiring
The metal wiring process is used to create the wires that will connect the transistors together. A thin layer of metal is deposited on the wafer, and then a photolithography and etching process is used to create the desired pattern of wires.
Electrical Testing
Once the metal wiring has been completed, the wafer is electrically tested to ensure that all of the transistors and wires are functioning properly. Any wafers that fail the electrical test are discarded.
Packaging
The final step in the semiconductor manufacturing process is packaging. The wafer is diced into individual chips, and each chip is mounted on a package. The package protects the chip from damage and provides a way for the chip to connect to other components.
The semiconductor manufacturing process is a complex and delicate one. The entire process of creating a silicon wafer with working chips consists of thousands of steps and can take more than three months from design to production. It requires a high degree of precision and cleanliness. However, the end result is a tiny chip that can contain billions of transistors. The microchip is now ready to get to work as part of your smartphone, TV, tablet or any other electronic device. It’s probably only about the size of your thumb, but one chip can contain billions of transistors. For example, Apple’s A16 Bionic system-on-a-chip contains 16 billion transistors and can perform 17 trillion operations per second.
