Why are 450mm wafers and EUV lithography related?
by Simon Favre
At the recent TSMC OIP, I had an interesting discussion with a TSMC employee (who shall remain nameless), regarding 450mm wafers. The gist of the discussion was that EUV has become a gating item for the move to 450mm wafers. Why are these two related? They are connected at the purse strings. It will cost billions (with a B) to build a 450mm wafer fab. It will cost billions to go to EUV. Why pay this kind of money twice? Although most of the other equipment in the fab might not care if the wafers were patterned with EUV or multi-patterning, the sheer cost of the steppers alone will keep TSMC (and others?) from moving to 450mm until they can bring EUV online at the same time. To put it another way, would you put in 450mm immersion steppers, and them yank them out to put in EUV before they’re fully depreciated? Even worse, what about the floor space? If the EUV steppers don’t have the capacity of immersion (they certainly don’t now), then you would have to allocate extra floor space for the EUV that you don’t need for immersion. Either that, or you have a lot of empty space waiting for the EUV steppers so you can run them side by side. None of these scenarios make fiscal sense unless you wait to go to 450mm until you’re satisfied with the EUV performance on a pilot line.
About Simon Favre
Simon Favre is the Technical Marketing Engineer for Calibre YieldAnalyzer. Simon has background in Processing, Custom Design, ASIC Design, and EDA. Most recently, Simon was at Ponte Solutions, which was acquired by Mentor Graphics in May 2008. Simon has extensive technical knowledge in DFM. Simon has worked with Foundries, IDMs and Fabless semiconductor companies worldwide to find the real value of DFM and to integrate DFM into their design flows.