Originally posted by: Pelu
So a processor is constructed by pieces and then you put them all together... like doing layer over layer only that the layer takes some time to complete the manufacture and the more layers you have on it.. the more time...??????
Sort of: the END PRODUCT of a processor you put in your computer is assembled with a bunch of pieces. However, the main piece, or the core is assembled by the following:
Taking a totally blank slate, which is a thin round wafer of pure silicon about 12" in diameter (unless they have moved up to 16")
Using chemical vapor deposition to deposit an ultra high purity layer of pure silicon that is doped (usually p-type meaning it has a lack of electrons, this enhances conductivity) on top of that. Doping is a process that just means introducing some other elements into silicon (example, about 1 atom of boron for every 1 million atoms of silicon would give you a p-type semiconductor)
Then they start the fabrication process:
depositing a polymer called photoresist onto the wafer, then using a lithography mask to burn an image into the photoresist, then removing the photoresist that was not affected by the lithography mask... This gives you a circuit pattern on the wafer that is carved out by the photoresist. Now, if you deposit some metal on the entire wafer: the areas that are covered by the photoresist will not have any metal on them, which means that you are left with a metal circuit pattern that covers the entire wafer.
they also grow layers of SiO2 (glass) which naturally grows out of the silicon if you expose it to oxygen at certain conditions,
they can also deposit patterns of metals, or other materials onto the wafer. In the case of intel's 45nm CPU's, they deposit hafnium oxide as the transistor gate oxide, which was one of the key features that made the 45nm process feasible.
basically building a processor is a complicated process of creating LAYERS of different materials on a very pure silicon wafer. In the end, you have some complicated circuits and millions of transistors.
Finally they need to provide connects to all the transistors. This is done by a crazy process of layering many many layers of conductive metal wires and oxides. Since there are millions of processors, there are a lot of layers of wires required.
Once the core is done, they have to provide wires to the processor, by using other processes to deposit gold wires that ultimately make contact with the pins you see on the bottom of your CPU.
All of this has to be done in an extremely clean environment. for example... dust is typically made of micro-meter sized particles (1000 nm) if a single piece of dust gets on a wafer, that wafer will have a really large fucked up area on it due to that one piece of dust, since you are building multiple layers on top of that piece of dust. It's kinda like the princess and the pea story.
Other things that aren't allowed in clean room environments: pencils. If you use a pencil, you will create graphite dust and graphite is conductive. If a piece of graphite falls on your CPU during fabrication, it is doomed.
It's a crazy process. Intel and AMD are simply amazing companies.
If you want to know more... electrical or chemical engineering classes often have semiconductor manufacturing options. I myself am a chemical engineer with a minor in semiconductor mfg.
Edit: just watched that video... not bad!
I dont even get through Precalculus... so I end up changing to management in college.
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