2:22 PM
Kinsz
It's not like sand can be poured into a toaster and Silicon Wafers pop out all ready to be used for making semiconductor ICs (integrated circuits) or solar cells. The process is extremely complicated and requires a lot of hi-tech equipment to achieve the precision required. Without delving too deeply into the geeky technical aspects, let's look at how the wafer is actually produced.
To start with, there's no need to worry about the raw material because Silicon (Si) is easily earth's most abundant element after Oxygen. The two combine together to make up SiO2 which is what most of the earth's crust is made of. Anytime there is a glint or glitter in the sand, that's the silica sticking its head out.
More importantly, monocrystalline Si has an incredible ability to conduct electricity in a controlled manner when dopants or impurities are introduced into the crystal structure. The first step is to get hold of the raw material (read sand) and convert it into pure polysilicon chunks using a chemical process. Many companies producing wafers do not make these chunks, but instead purchase them from other producers down the line.
These chunks are the raw material for the crystal pulling stage of the process. They are put into a CZ furnace along with a small amount of dopant like Boron, Antimony, Arsenic and Phosphorus. After the mix turns a melt under the 1420 degree Celsius heat, dissolved oxygen is introduced. To get a well rounded ingot, a seed crystal is lowered into the melt and rotated while it is extracted.
Since these ingots will be oversized and are not perfectly round, they have to undergo grinding. Once the ingot has the required diameter and round shape, it is notched or given a flat to indicate the orientation. Now this is where the ingot finally gets sliced into silicon wafers using an inside diameter (ID) saw.
There is a lot more to be done, because the wafer is thick and has defects and saw cuts. Edge grinding is applied to make the wafer sturdy and well rounded. Lapping at this point simultaneously gets rid of the extra thickness and the imperfects on the front and backside of the wafer.
The wafer is then polished, cleaned and subjected to QA checks. This won't be a human quality control team looking at the silicon wafers. It needs sophisticated equipment to precisely measure the wafer's thickness and TTV (total thickness variation), resistivity and other parameters.
To start with, there's no need to worry about the raw material because Silicon (Si) is easily earth's most abundant element after Oxygen. The two combine together to make up SiO2 which is what most of the earth's crust is made of. Anytime there is a glint or glitter in the sand, that's the silica sticking its head out.
More importantly, monocrystalline Si has an incredible ability to conduct electricity in a controlled manner when dopants or impurities are introduced into the crystal structure. The first step is to get hold of the raw material (read sand) and convert it into pure polysilicon chunks using a chemical process. Many companies producing wafers do not make these chunks, but instead purchase them from other producers down the line.
These chunks are the raw material for the crystal pulling stage of the process. They are put into a CZ furnace along with a small amount of dopant like Boron, Antimony, Arsenic and Phosphorus. After the mix turns a melt under the 1420 degree Celsius heat, dissolved oxygen is introduced. To get a well rounded ingot, a seed crystal is lowered into the melt and rotated while it is extracted.
Since these ingots will be oversized and are not perfectly round, they have to undergo grinding. Once the ingot has the required diameter and round shape, it is notched or given a flat to indicate the orientation. Now this is where the ingot finally gets sliced into silicon wafers using an inside diameter (ID) saw.
There is a lot more to be done, because the wafer is thick and has defects and saw cuts. Edge grinding is applied to make the wafer sturdy and well rounded. Lapping at this point simultaneously gets rid of the extra thickness and the imperfects on the front and backside of the wafer.
The wafer is then polished, cleaned and subjected to QA checks. This won't be a human quality control team looking at the silicon wafers. It needs sophisticated equipment to precisely measure the wafer's thickness and TTV (total thickness variation), resistivity and other parameters.
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