201305.pdf 43279KB May 08 2013 11:07:04 PM

DESIGN FORMANUFACTURING&YIELDWITHOUT INCREASINGLYSOPHISTICATED SOFTWARE,MANUFACTURING AT 28NM HAS BECOME HIGHLYPROBLEMATIC AND YIELDSUNECONOMICALLY LOW.WHAT CAN BE DONE TOENABLE THIS AND SMALLERNODES TO REACH THEDESIRED YIELDS?BRIAN BAILEY • CONTRIBUTINGTECHNICAL EDITORIMAGE: SHUTTERSTOCKAs designs move to the28-nm and smallernodes, the likelihood ofa design being manufacturedwithout defects trendstoward zero unless a rapidlygrowing set of rules is adhered to. Those rulesare increasing in number and complexity. Theabsence of extreme ultraviolet light sources meansthat double patterning has become essential andnew devices, such as 3-D transistors, are beingadopted. But it does not stop with just manufacturability.Lithographic features affect functionalityand performance in such a way that yield hasalso become a primary concern.Here we examine the problems and the waysin which increasingly sophisticated software canbe used to overcome the limitations of technology.Representatives from five different companiesdiscuss, from their own perspectives, theseissues as well as solutions.WHY HAS ITBECOME SUCH AN IMPORTANT TOPIC?Shrikrishna Mehetre, Director of Engineering,Open-SiliconMajor contributors to yield loss are:• Geometric variations during the manufacturing processmay result in performance variations that can pushthe device out of the allowed 3-Sigma variation, causingparametric yield loss.• Specific patterns on the die may not get manufacturedas desired because of diffractions that happen during thelithography process, causing catastrophic failures on thedies.• Random defects may induce shorts or opens on thewafer, resulting in yield loss.• The wafer goes through chemical mechanical pol-[ www.edn.com]MAY 2013 | EDN 27