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

To: Dan3 who wrote (237576)	7/29/2007 1:06:42 AM
From: wbmw	Read Replies (1) \| Respond to of 275872

Dan, do you not understand the difference between line yields and die yields...? The loan agreement says that AMD's line yield cannot fall below 75%. Line yield refers to the number of wafers that get completely scrapped. Out of the thousands of wafer starts every week, sometimes a few lots experience a problem, or a machine breaks down in the middle of its procedure, forcing the complete disposal of all of the wafers in the lot. Clearly, getting below 75% line yield would mean a quarter of all wafers are being scrapped, which would be a pitiful state of affairs. I'm sure AMD's line yields are in the 90s of percentile. On the other hand, die yields are an entirely different story. These depend on the size of the die, and are usually measured in defect density, not in percentage of die (which varies from design to design). There is no way the loan agreement would refer to die yield, since there's no way even world class yields would allow a 284mm^2 die to yield at 75%. Based on this document, the ITRS designs specifications to allow for 0.22 defects/cm2 for high volume MPUs. itrs.net siliconinvestor.com For a 284mm^2 die on 300mm wafers, this would be 55% die yield. AMD's defect density, however, is somewhat less than 0.5D/cm2, which lowers yield to around 29%. This is far from world class, but may easily satisfy the stipulations in your previous link.

To: Dan3 who wrote (237576)	7/29/2007 1:54:56 PM
From: brushwud	Respond to of 275872

If 3/4 of the parts on production wafers coming out of the Dresden lines aren't working parts, the loan covenants are violated. The 75% figure in that agreement only pertained to a certificate to be issued by a "Technical Adviser" regarding one four-week period, which was one aspect of "Technical Completion". That step in the equipping of Fab 36 presumably having been met, it is no longer operative, and discussion about the definition of "yield" in that clause is now irrelevant.