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From Silicon To Microprocessors
prostoalex writes "Jim Turley from Embedded Systems Programming magazine answers the question of where microprocessors come from. While the public generally knows about the silicon and microprocessor vendors, few can describe the process of turning the beach sand into the latest and greatest several-hundred-dollars-worth CPU."
I read the article and find myself actually knowing in advance how silicon chips are made. You see, in the 80ies we had childrens books about computers that covered something more than how to start Word and update Winblows.
While informative on what it touches on, this doesn't describe what goes into making a chip. It describes how a chip is patterned. Then follows many many diffusion, oxidation, etch, and metallization steps that go between each photoresist mask step. I suppose it makes a good read for someone who wants just a general overview. But it makes it sound like making a chip is just a glorified film development process. I do microfab work, and the lithography steps are the steps we take for granted (mostly -- they still do take effort to get right, but are in general easier then what follows).
From the article:
For an example, let's look at a 200mm silicon wafer, which has about 986cm2 of surface area. That's about the size of a salad plate. Let's say your chips are square (most are) and they measure 10mm on a side?that's 100mm2 per chip. If the silicon wafer was also square you could fit 986 chips on your wafer. Alas, wafers are round so you can really only get about 279 chips on a wafer.
I guess the obvious question, since using squares on a round wafer wastes a certain amount of silicon, is why squares? Why not build a hex grid? That would seem to maximize the usage of the available area.
But then, I suppose cutting them out would be significantly more difficult.
What about triangles, then? Straight lines up and down, and in one (or both) diagonal directions.
On the other hand, someone's already thought of this:
Intel's old i960MX microprocessor was octagonal. It was so big its corners had to be cut off.
So my idea has an obvious flaw. The question is... what is it?
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
I thought big screen TVs were "blurry" up close because they had fewer pixels per area. Besides... in this case, you wouldn't be making the image bigger, you would just be making a LOT of tiny images at once. Can someone either explain how his explaination makes sense, or what the real reason is?
The article mentions that, with co-workers encased in bunny suits, you have to look at their eyes to tell people apart. When I worked in a fab, I noticed I became very attuned to people's body shapes and ways of moving. After working there for a while, I could subconsciously identify co-workers at the opposite end of a shopping mall, simply by the way they walked.