When you form a layer of oxide on a silicon wafer, the color of the wafer changes according to the thickness of the oxide. This property is useful for eyeballing the thickness of your oxide, and certainly for visually identifying which wafers have been oxidized. It's also been used to create chip art (There's more on—and more—chip art at the Chipworks Silicon Art Gallery and some downloadable chip art wallpaper at Florida State University's Molecular Expressions) and, of course, IC chips.
Today in microfabrication, the professor mentions the difficulty of getting the resist to adhere to the wafer and how sometimes they end up spending hours in the lab trying to get resist to stick on a wafer that's being patterned with an image and text to give to a university donor. Mostly because they use old wafers that have been sitting by the oven for years. "Maybe you've seen them lying around the lab? You'll all get to make one at the end of the class. You can put anything you want on it—"
"Hey!" The class perks up.
"—as long as it's not obscene."
"Aw, man!" The back row is disappointed. I wonder what they wanted to put on their wafers, but I think I'd rather not know.
So, what shall I put on my wafer? I'm thinking of something for Oz, along the lines of "My girlfriend went to engineering school for seven years and all I got was this lousy wafer" or maybe something in Japanese like a big 気 (ki). Oz says that since I'm so miserable in the clean room I ought to keep the wafer as a reward (to remember the experience by?), but I can't think of anything to put on it. Maybe a riff on Rene Magritte's La Trahison des Images: "Ceci n'est pas un wafer." Or maybe Kitty-chan, she's everywhere.
317 words | February 16, 2005 11:01 PM | Ivory tower