Manufacturing a CPU in your own home (Part 2)
Well, you've come this far. You are keen
. That's a good thing
. Rome wasn't built in a day
Microprocessors are built in layers on silicon wafers through various processes using chemicals and light.
The first layer of silicon dioxide is grown by exposing the silicon wafer to extreme heat and gas. This growth is similar to the way rust grows(3). Thermal oxidation of silicon is easily achieved by heating the substrate to temperatures typically in the range of 900-1200 degrees C You might balk at these kind of figures but remember that's a rough guide only and you have time on your hands. If however you want to really get into the big end of town i recommend dismantling all heat producing appliances in the house. Anything with a coil - heaters, lights, electric kettles - pull them apart and shove the elements in the oven with electrical cables still attached to each element. This will help ramp up that temp and in no time you'll be cooking with the best of them. If you get impatient maybe add some flammable liquids.
The atmosphere in the furnace where oxidation takes place can either contain pure oxygen or water vapour. At this point you can take your pick. If you want to be *trendy* and impress your friends, use oxygen. I prefer the hands on deal and like to get some hot water vapour action going. Get a spray bottle and spray some water in there. Simple! The silicon dioxide on the wafer grows fast and is too thin to be seen by the naked eye. So ... DON'T BE ALARMED IF NOTHING LOOKS TO HAVE CHANGED! Have faith that if you follow the instructions contained herein everything will be ok.
We won't be using this fancy schmancy
photoresist. We want a man's processor - tough, rugged and reliable! Go to your freezer
and get out a sheet of puff pastry
and whack it on top of the silicon dioxide. Give it one or two rolls to flatten it out and then trim the edges. Resist your cooking instincts - DON'T COAT WITH AN EGG WASH
! Place a damp towel over the puff pastry so it doesn't dry out.
Make a mask and "beam" it onto the puff pastry
Now you need to get creative and draw up a set of masks for you processor. I often make my masks up into the shape of farm animals. You want the pattern to not only be functional but also pleasing to the eye. Draw your pattern on some magical shrinky dink plastic sheets and cut the pattern out. Put them in the oven and watch them shrink! Now place the mask over the puff pastry and just follow the lines! This IS getting exciting. You might have to get really close to the mask to see where your cutting, but with skill and patience you'll be there in no time. Who needs expensive photolithography equipment?!?! Not too mention harmful UV light making you infertile
Splash acid all over the damn thing! Take off your mask and you'll find a nice ridge of silicon dioxide in the shape of your mask.
Now you need to add another layer of silicon dioxide. Then a layer of polysilicon... err. i mean floor wax (use an artist's brush because you are an artist after all. A CPU artist), then some more puff pastry. Make some more masks and etch them back over the whole lot again.
Now you've got ridges of silicon, silicon dioxide, floor wax and puff pastry. Hold back those tears of joy for just a moment. Maintain control as well enter into the next stage
Ion love blasting
In this step we bombard your etched marvel with chemical impurities call ions. To do this we need some household dirt, belly button lint and toe jam. You won't need much. When you've got only a small amount smear it into the groves of your masterpiece. Mash it in. Maybe even take it outside in the dirt and smoosh it around. Jump on it! Good work. The areas that trap the chemical impurities will alter the way electricity is conducted around the chip.
Layers upon layers
Repeat the layering and masking process to make windows that allow connections between layers. Fill the windows with iron filings that you can make by grinding down bicycles. You'll need about 20 layers all together. I believe this is how Sara Lee does it.
You've made one microprocessor. Now get to work on microprocessor number 2 of 666 processors we'll be making on this one wafer of silicon. Soon you'll have cornered the CPU manufacturing market.
3 Note: In theory I believe that you could actually turn your own car engine into a large mobile CPU by draining out the oil and allowing it to sit in salty water for one week. Following this you would be required to do some of the steps described below.(4)
4 This may not be possible. Only tested on 1.6 litre, 4 cylinder Japanese manufactured motors.