Silicon wafers are a big component of modern-day electronics. They’re the prime material of semiconductors. You may have already heard the term, and you more likely than not are using them in your home or at work at this very moment. But what exactly are these wafers? Where do they come from? Keep scrolling to find out and even where you can even pick some up for yourself.
What are Silicon Wafers?
To be quite blunt, the main component of Silicon Wafers is of course Silicon. Si is the second most common element on Earth right after Oxygen. It’s found in the ground (predominantly in the earth’s crust) and although it has a cool metal sheen it actually has a metalloid classification. This means they have the potential to behave like metals but are comprised of nonmetal elements as well.
Silicon is then fabricated into a wafer, this makes it thin and grants it the ability for use in semiconductors. They must have a 99.9999999% purity level to be effective. Depending on the wafer’s purpose however various dopants can be included to alter or modify the silicon’s purity. This can include other metalloids boron or other elements such as aluminum, nitrogen, and gallium. This will make the semiconductor either extrinsic or degenerate depending on when the dopant was added during the process.
How are Silicon Wafers Manufactured?
The wafer itself is incredibly thin and extracted from pure Silicon found in sand. However this sand is professionally studied and obtained and is not at all like your common beach sand. Wafers are made from Silicon because it’s abundant in supply, generally inexpensive, and a great conductor.
Once the silicon is extracted from the sand the purification process must take place in order for the wafer to actually work. The Silicon is first heated and melted to remove any impurities and is then solidified into an ingot or rod typically using the Czochralski method (although the Floating Zone method can be used as well). This allows it to be easily cut into a disc shape of varying diameters before it is completely cooled. It used to be the case that all wafers only had a 3” diameter, but due to advancements in technology wafer size has been steadily increasing - larger wafers hold more chips which increases productivity.
Wafers are then polished using a combination of acids - either incredibly abrasive or very light determined by what the wafer is going to be used for. This creates a wafer with a mirror-like and flawless finish. A pure surface on the wafer will make the circuit patterns print better. This circuit pattern will take the wafers from a non-conductive to semi-conductive state after various substances are also added to the wafer.
From there a layer of SiO2 is added on top of the Silicon substrate. A layer of oxygen will protect the wafer from pollutants or impurities that can contaminate the wafer, rendering it inoperative.
An etching process then takes place to selectively remove unnecessary parts until a desired circuit patterns are left on the wafer surface. This can be done with liquid or plasma etchants. The method used depends on the material being etched - however the oxidized layer will prevent parts of the Si layers being damaged during the process or weathering away the key conductive components.
The etching method can also be an incredibly dangerous one and many precautions should be taken beforehand. Be sure your environment is well controlled and consult an expert to ensure every process is performed accurately.
When Do You Use a Silicon Wafer?
Silicon wafers spend their life as an optimal semiconductor. Silicon is the most used semiconductor because it’s extremely mobile at room and high temperatures. In electronic devices currents can pass via Silicon much quicker compared to other conductive elements.
Almost all modern day electronics use silicon wafers to produce chips and microchips. They are also the basis of many the basis of memory chips, computer processors, and transistors. They’re also used in creating integrated circuits which create specific commands in various devices. They’re also incredibly present in many of today’s smartphones and mobile technology.
What Else Should I know?
Silicon wafers are incredibly durable and can function in varying extreme temperatures so they’re used in manufacturing across the globe. The U.S. leads the Silicon wafer market share and makes up for 51% of the worldwide market. In 2015 more than 10 million square inches of silicon had been shipped globally.
Many manufacturers will only supply silicon wafers in large amounts or bulk orders. This is because the creating quotes for individual ones can be time consuming given the different sizes or wafer functionality. Some online suppliers such as University Wafer will quote for individual wafers if you only need one replacement or for various individual needs.