as detailed as possible without the need of years of experience to understand. detailed enough to be educational! haha
OK, I'm going to assume a basic understanding of the fundamentals of semiconductor technology here, if you lack that, wikipedia article for transistors or something like that will be more than sufficient to get you up to speed. The way the manufacturing process for semiconductors works is rather simple. You take a semiconductor (typically silicon, but germanium is starting to see a rise in popularity in some of the hsld stuff like the new solar panels and such...OT but interesting) and you create, often through a chemical reaction, an oxidized layer on top of it. In the case of silicon, you're looking at SiO2
. This is your starting point for anything based on semiconductors.
From here, to create a transistor, you have to remove some of the oxide. The means by which this is done is with really powerful lights and such through a process called etching (which is really complicated and not relevant enough ot the discussion to warrant explanation, sufficient to say that the oxide is removed). The important thing to note here is that the whole wafer is not done at once, but rather individually from the same mask through movements of the mask and/or the wafer to get correct placement of the pattern on the wafer. This process is repeated many times to create a multi-layered pattern (with an oxide removal step added).
The wafer is then tested as a whole, then split to chips, then those chips are tested and such...the actual process from here is generally irrelevant, as the differences in the silicon have already been established. For those of you following along at home, now is your time to solve the mystery! Where was the difference in the chips introduced? That's right! It has multiple sources! The one you probably didn't think of was impurities in the silicon. Without a thorough discussion of material properties, it's difficult to explain how this could affect the clocks the processor could attain, but the long and short of it is that it changes the conductivity of the material (which actually affects many other things......but that's a different discussion). The other one comes from the etching process itself. The machines that do the etching can only be so accurate, and while they are some of the most accurate ever seen in the history of this planet, the variations are minor enough that different chips can have different properties. This can come from anything from the mask being a little skewed to the lighting having been uneven. This is also why sometimes a certain chip out of every batch will clock better, the chip in the position that gets the most perfect etching will clock the best.
It should be noted that I've summed up a lot of stuff here...this is by no means comprehensive, I tried to keep it simple. There are other sources of error, but those are your main 2. Also, take all of this with a grain of salt, I'm pretty tired right now, so I might have messed something up, if you catch anything, please call me out on it!