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Technology Stocks : Advanced Micro Devices - Moderated (AMD) -- Ignore unavailable to you. Want to Upgrade?

To: hmaly who wrote (73899)	3/7/2002 5:22:24 PM
From: semiconeng	Read Replies (1) \| Respond to of 275872

Excuse my ignorance, but when they scan, can they scan only one die at a time, a block of 2 or 4, or the whole wafer. Depends, There is a Maximum size Mask that a stepper can handle, but I'm not sure if that size is Company confidential. How many die can fit on a Mask depends on the reduction ratio of the Stepper, and the die size. If a Stepper, due to Lens quality, has a reduction of 10:1 for example (not real numbers), you need to draw the chrome pattern on the Mask (minimum) 10 times the size of the die. Some small die can fit 3/4/5/6 die on a Mask, some larger die can only fit 1/2. Shrink the die, shrink the chrome pattern, fit more chrome on the mask. That's why I said that "sometimes" you can get an additional die on the mask, depending on the previous die size, the Reticle Mask Size, and the Reduction Capability (Lens Quality) of the Stepper. Without knowing AMD's reticle size, or what steppers they're using, It's hard to tell the number of die on their masks. And of course, Phase Shifting throws a whole new set of Parameters (ie: problems) into the mix. You need a new Mask for each "Layer Shrink" (Usually called "A New Stepping"), and most likely a completely new set (every layer) for an entire die shrink. Of course, with an industry standard throughput of 10-12 weeks, you don't necessarily need all the Masks to be available on-site, in order to start the shrink wafers. Of course, if you take that risk, and your Masks don't show up in time, or there's a problem with the Mask, the whole line could stop dead at the Missing/Problem Mask Layer. I've never seen a Mask that can shoot a whole wafer. Imagine the complexity required to create that mask! Semi