Excavator in 2011-2012 @ Sunnyvale teams put it on 20-nm LPM.
Excavator in 2012-2013 @ Boston teams put it on 28-nm SLP. (LP node shared with Samsung; SLP = LPP or ET-SOI = FD-SOI)((It is required to be shared with Samsung for AMD to use it))
~2012 -> Steamroller and Excavator was moved from Sunnyvale teams to Boston teams. So, Sunnyvale could design from scratch a new high performance x86 core. Like, they did in 2005/2006 to 2010 called Bulldozer.
Steamroller was unfixable as it was largely complete when Boston got it. While, Excavator is a complete mystery. As it was at an incomplete state on 20-nm LPM.
The majority of the Boston team are part of the FD-SOI community as well.