We don't need to tell you that modern digital devices—smartphones, PCs, game consoles, etc.—are powerful technologies. Much of that power comes from microchips. In 2020, more than 1 trillion chips were manufactured worldwide. But despite their widespread availability, making microchips is no mean feat. To make any chip, many processes come into play.

Let's discuss six key semiconductor fabrication steps: deposition, photoresist, lithography, etching, ionization, and encapsulation.

Deposition

The process starts with a silicon wafer. Wafers are cut from salami-shaped strips of 99.99% pure silicon and polished to an extremely smooth finish. Thin films of conductive, isolating or semiconducting material - depending on the type of structure being fabricated - are deposited on the wafer so that the first layer can be printed thereon. This important step is often referred to as "deposition".

Photoresist coating

The wafer is then covered with a light-sensitive coating called "photoresist." There are two types of resists: positive resists and negative resists.

The main difference between positive and negative resists is the chemical structure of the material and the way the resist reacts with light. With a positive resist, areas exposed to UV light change their structure and become more soluble. Negative resists, on the other hand, polymerize the areas hit by light, which means they become stronger and more difficult to dissolve. Positive resists are most commonly used in semiconductor fabrication because their higher resolution capabilities make them a better choice for the lithography stage.

Lithography

Lithography is a critical step in the chip manufacturing process because it determines the size of transistors on a chip. At this stage, the chip wafer is inserted into a lithography machine, where it is exposed to deep ultraviolet or extreme ultraviolet light. Light is projected onto the wafer through a "reticle" that contains a blueprint of the pattern to be printed. The optics of the system retract and focus the pattern onto the resist layer.

Etching

The next step is to remove the degraded resist to reveal the desired pattern. During the "etch" process, the wafer is baked and developed, and some of the resist is washed away, revealing a 3D pattern of open channels. The etching process must precisely and consistently form increasingly conductive features without compromising the overall integrity and stability of the chip structure.

Ionization

Once the pattern is etched in the wafer, the wafer can be bombarded with positive or negative ions to adjust the conductive properties of parts of the pattern. Guiding charged ions into a silicon crystal can control electrical current and create transistors -- electronic switches that are the basic building blocks of microchips. This is "ionization", also known as "ion implantation".

Encapsulation

The entire process of creating a silicon wafer from a working chip involves thousands of steps and can take more than three months from design to production. To remove the chips from the wafer, it is cut into individual chips with a diamond saw. Cut from 300mm wafers (the most commonly used size in semiconductor manufacturing), these so-called "die" sizes vary from chip to chip.

The chip die is then placed on the "substrate". This is a substrate for microchip chips that uses metal foil to direct the chip's input and output signals to the rest of the system. To close the lid, a "radiator" is placed on top.The heat sink is a small flat metal protective container that holds a cooling solution that ensures the microchip stays cool during operation.

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