Originally posted by zeeblebot
From Sand to Silicon: How a CPU Is Made
Ever wonder how Intel makes a CPU? Here's a glimpse at some of the amazingly sophisticated work going on daily inside those cutting-edge fabrication plants.
A tad simplified
My deal was step # 14, ion implantation. But in my work they implanted at that step but also much earlier in the process, when the wafer had no patterns, because pure silicon is a good insulator and implanting ions, the big three being Arsenic, Boron, and Phosphorus, it is those atoms taking the place of a silicon in its crystal structure that allows conductivity, a process called 'doping'. They also skipped the step after implantation called 'annealing'. which is where the magic happens. The ion implantation step slams one of those big three into the surface of the silicon wafer and at speeds of up to 250,000 miles per hour, an acceleration voltage of 200,000 volts or more (newer generation of chips need lower voltage acceleration and so slower moving ions, a complex issue to explain in one paragraph or two). But the incoming ions plows up the surface of the silicon crystal which has nice ordered array of silicon atoms in a nice orderly structure. So the top layer is amorphous now, a jumbled up mix of silicon and whatever dopant has been implanted and is no longer a crystal on the surface. It is still crystalline deeper down however. Here is where the magic happens:
When you take that wafer and put it in an oven at around 1000 degrees C for about 30 minutes or a couple of minutes on a 'Rapid Thermal Annealer', the crystal structure reforms from the bottom up and now incorporates the dopant atoms in the silicon matrix. That seems magical to me, the reforming into a crystal after being totally plowed up after the implantation step. Now the silicon can go to the next steps in line to becoming a CPU or whatever.