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To: Yousef who wrote (75566)	3/25/2002 10:27:28 PM
From: Elmer	Read Replies (2) \| Respond to of 275872

Defect density MATTERS !!! You know this goes right over their heads don't you? If they were smart enough to understand this they would have figured out the line of sh*t Jerry is feeding them. EP

To: Yousef who wrote (75566)	3/25/2002 10:58:09 PM
From: pgerassi	Read Replies (2) \| Respond to of 275872

Dear Yousef: You forgot the most valuable point! The smaller die at the same defect density has a much higher yield. In other words, big is bad! Defect density does not vary that much between cutting edge fabs at similar times as the wafers supplied to each fab come from the same sources (and any big differences would cause a shift in suppliers so they have great incentives to deliver product with not much larger defect densities than competitors). And most of those defects are caused by the underlying wafer are they not? Thus, the highest variable in these equations in typical use is the die size. And that does not favor Intel. Pete

To: Yousef who wrote (75566)	3/25/2002 11:00:11 PM
From: Dan3	Read Replies (2) \| Respond to of 275872

Re: Here are the two most commonly used equations for calculating yield from defect density and die size That's very helpful, Yousef. We already have the die sizes. Now be a nice fellow and post the defect densities of Intel and AMD's leading processes so we can plug in the numbers. Thanking you in advance, Dan

To: Yousef who wrote (75566)	3/26/2002 12:38:51 AM
From: hmaly	Read Replies (1) \| Respond to of 275872

Yousef Re...Yield = [[1 - e^-AD]/AD]^2 ... A = chip area in cm^2 ... D = defect density in defects/cm^2<<<<< Thanks for the post. I have a couple of questions. From previous discussions, I had assumed "defect density" meant the number of defects expected in a area of silicon before processing, which would of itself destroy a chip. Your formula for BE also includes a multiplier of n for the number of layers, but the MUR formula doesn't. Why? What determines defect density. The no. of bad chips, or the defects one can expect in silicon? If the defect density is compiled by totaling bad die/cm^2, are all processing errors called defect densities.