Vacuum doesn't suck, Part 1.

Several of you already know and understand the things I'm going to say, and others might be bored by it, but I think it's way cool. As I mentioned, when I first entered the semiconductor industry, I was lucky to be assigned to high vacuum equipment. Along the way I worked on many other types of fab equipment, but mostly it was vacuum, and that was the most interesting by far. I even became a member of the American Vacuum Society, which is impressive in some circles. Not that I really deserved it. To join you have to take some classes and then be nominated by three AVS members. Taking the classes was easy, but then what? I didn't even know any AVS members. I solved that problem by going with a fat dead guy from Timex to an AVS conference in Denver. I learned that if you go around and ask strangers to nominate you, eventually you'll get the signatures, especially if you wind around to the same person three or four times.

What is vacuum, anyway? Well, that's a good question. Maybe the best answer is that vacuum is nothing, and it doesn't suck. That's probably a good thing to remember when you're vacuuming your carpets.

We are at the bottom of an ocean - the atmosphere. It's a lot like more familiar oceans, except that there are birds instead of fish. And it weighs a lot - 14.7 pounds per square inch. Fortunately, our internal pressure matches that, so we don't get squished. The downside is that if we got thrown into a vacuum like space, our blood would boil and we'd blow up. But that probably isn't worth worrying about, unless Obama loses in 2012.

Vacuum is someplace air isn't, a hole in the atmosphere. We're all painfully familiar with vacuum cleaners, a simple vacuum pump. Basically they're a fan that blows air from the hose out through some filters. If you put your hand against the end of the hose, it will feel like it's being sucked in, but it isn't. Vacuum doesn't suck. What's happening is that the atmosphere is pushing on your hand more than the hose is. Your hand is being pressed against the hose, not being sucked into it.

That might be handy to remember when you're vacuuming. Dirt isn't being sucked into the vacuum cleaner, it's being blown in by air rushing into the hose. That's why it's a good idea to use the rotating brush - it kicks dirt particles up where they are most likely to be caught in the air stream.

It's easy to create low vacuum with a fan or other simple device. But semiconductor processing and other processes require high vacuum, where a fan is ineffective. Gases have to be removed on a molecular level, and how that's done is (I hope) interesting.

TBC...