Thread View: comp.lsi.testing
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Started by Gerald M. Spiegel
Fri, 22 Jan 1993 14:41
IC Defect Statistics
Author: Gerald M. Spiegel
Date: Fri, 22 Jan 1993 14:41
Date: Fri, 22 Jan 1993 14:41
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Anyone who deals with product quality and yield of integrated circuits probably has the same problem: Where can I get realistic data about defect densities and defect size distributions concerning a certain manufacturing process? Well, so do I. For my opinion, we should stick together and share the little information we have. So here is my call: Please email ANY information you have about defect statistics, if you think it might be usable. No, you are not asked to let out any internal company affairs, because the information shall be summarized and posted. Any help is greatly appreciated. Gerald M. Spiegel -------------------------------------------------------------------- UNIVERSITY of KARLSRUHE (Germany) Department of Computer Science Institute of Computer Design and Fault Tolerance Phone (+49) (721) 608 4227 P.O. Box 69 80 FAX (+49) (721) 370 455 W-7500 Karlsruhe 1 email: gerald@ira.uka.de --------------------------------------------------------------------
Re: IC Defect Statistics
Author: sheldon haynie
Date: Tue, 26 Jan 1993 13:18
Date: Tue, 26 Jan 1993 13:18
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in previous post Gerald M. Spiegel says: >Anyone who deals with product quality and yield >of integrated circuits probably has the same problem: >Where can I get realistic data about defect densities >and defect size distributions concerning a certain >manufacturing process? Well, so do I. >For my opinion, we should stick together and share >the little information we have. >So here is my call: Please email ANY information >you have about defect statistics, if you think it >might be usable. >No, you are not asked to let out any internal >company affairs, because the information shall >be summarized and posted. >Any help is greatly appreciated. Here's some info from previous processes that I have known well. These data are 3-15 years old and *should* be therefore pessimisitic estimates. Don't ask which fabs, because it doesn't matter. These were all reproducible manufacturing numbers, in companys from Fortune 500 to start-ups. Obviously, *Yield* must be separated from *defect density* by a coherent strategy that eliminates testing, parametric and design issues. With SRAM or DRAM cells, or by arbitrarily grouping adjacent linear die you can synthesize enough yield vs area information to develop a curve. Take *lots* of data (> 10,000 wafers) before you decide what your D and Alpha are. In 1988 I was priviliged to attend a Defect reduction course at RPI with a presentation by Dr. Stapper... he put up sanitized data that showed the IBM General Tech. Divisions Historical Defect reduction on a log scale. The units were arbitrary, but the slope was near constant from '69 to '86... Model parameters are for a "Stapper" gamma function defect distribution which fit my data better than exponential, Murphy/Moore or Seeds. Your milage will vary. Note: defects do cluster, the distributions are not simple. Stapper's eqn: Yield = (1 + AD/alpha)^-alpha where alpha is the parameter for wafer to wafer variations Technology Design Feature Wafer D(/cm^2) Alpha Tooling ________________________________________________________________________ Bipolar slm Linear 5 um 100mm 2.5 1.3 PE 341 Bicmos dlm Linear 3 100 1.02 .8 PE 341 CMOS slm digital 5 100 10 3 Canon Prox. CMOS dlm digital 2 100 5 3 PE 341 CMOS dlm digital 1 100 3 2 5:1 DSW Bicmos dlm linear 2 100 10 3 5:1 DSW DMOS slm disc. 4 100 8 2 Canon Prox. DMOS dlm disc. 5 75 7 2.5 Canon Prox JFET slm disc. 2 50 20 .3 K&S contact Bipolar slm disc. 10 75 50 .5 K&S contact Notes: slm = single metal dlm = double metal The tooling and possible redundancy of the circuits will dramatically affect yields... Note that the contact printers (ca 1978) with emulsion masks gave very consistent (small alpha) results. Sheldon Haynie | Unitrode IC Corp | 7 Continental Blvd. | Merrimack, NH 03054 | FAX:603-424-3460 |voice:603-424-2410 (EST)| sdh@.uicc.com *********************************************************************
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