Semiconductor Manufacturing Explained in 6 Simple Steps

Semiconductor Manufacturing

Microchips exist in many electronic devices today. Users often remain unaware of these microchips until their device fails. They then want the device repaired as quickly as possible. In fact, manufacturers produced more than one trillion microchips in 2020, and it wasn’t enough. The world experienced a microchip shortage that left many people without their devices. Why is it so difficult to produce these items in the quantities needed?

Before producing microchips, a company must have the right equipment for wafer fabrication. In addition, each chip moves through six processes during the fabrication process. What are these steps?

Step 1. Deposition

First, the manufacturer secures 99.99 per cent pure silicon. They slice this silicon into wafers and polish those wafers until they are smooth. Next, the manufacturer deposits a thin film on the wafer to allow the printing of the first layer. This film can be made of semiconducting, conducting, or isolating materials, depending on what the chip will be used for. As the microchip structures decrease in size, the complexity of patterning on the wafer increases.

Step 2. Resist Coating

The second step involves applying a light-sensitive coating to the microchip. This coating, known as photoresist or resist, comes in both positive and negative types. The material’s chemical structure and the reaction of the resistance to light determine whether the coating is positive or negative. If the structure changes when exposed to UV light and becomes more soluble, this is a positive resistance. Manufacturers use positive resist for etching and deposition.

When areas hit by light become stronger and less likely to dissolve, this is a negative resistance. The areas polymerize. Semiconductor manufacturers rely heavily on positive resist, as it allows for higher resolution capability.

Step 3. Lithography

Lithography dictates the size of the transistors on a chip. The manufacturer inserts a wafer into a lithography machine. This machine exposes the wafer to deep UV or extreme UV light. The wavelength of this light ranges from 365 nm to 13.5 nm, depending on the complexity of the finished chip. A reticle projects the light onto the wafer. This reticle stores the pattern’s blueprint. Optics within the system shrinks and focus the pattern so it can be applied to the resist layer.

Manufacturers find it difficult to get the pattern perfect every time. Many things may interfere with this process. To overcome these disturbances, the manufacturer optimizes the pattern, doing so by deforming the blueprint. This results in the actual pattern that is needed, although the blueprint may appear different from the printed pattern.

Step 4. Etch

Once the resist degrades, it is removed to reveal the pattern. The etching process involves baking and developing the wafer before washing some of the resists away. This uncovers a 3D pattern made up of open channels. This process must form conductive features precisely and consistently. When doing so, it cannot impact the stability and integrity of the chip’s structure. Advanced technology allows manufacturers to create tiny features in these chips.

Manufacturers must carefully control the etching process to protect the underlying layers of a multilayer structure. If a cavity is to be created in the structure, the etching process must create the correct cavity depth. This step continues to increase in complexity, as some chips have up to 175 layers.

Step 5. Ionization

Upon completion of the etching process, the manufacturer may bombard the water with positive or negative ions. Doing so tunes the electrical conducting properties of different parts of the pattern. This is important because silicon isn’t a perfect insulator or conductor. The electrical properties of this material fall in between the two extremes. By directing these electrically charged ions into the silicon crystal, the manufacturer gains more control over the flow of electricity and the creation of transistors. Once this step is complete, any remaining areas of resistance are removed.

Step 6. Packaging

Creating silicon wafers can with functioning chips can take months. Removing the chips from the wafer requires the slicing and dicing of the wafer with a diamond saw. Each individual chip is then placed into a substrate or baseboard. The substrate or baseboard uses metal foils to direct the input and output signals of the chip to other system parts. Finally, a heat spreader or small, flat protective container is placed on top. This metal container holds a cooling system to ensure the chip doesn’t overheat when used.

Upon completion of this process, the microchip is ready for use in an electronic device. While it may be no bigger than a human thumb, this chip holds countless transistors. The semiconductor manufacturing process involves more than the steps mentioned above. Manufacturers must measure and inspect the chips, test them, and more. Remember this the next time an electronic device is used. Without these manufacturers, humans would have a completely different life today.

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