@Rick Merritt: the title of the article is misleading -20nm TSV's! You should have phrased it as TSV's for 20nm process nodes.
Very few are producing large volume TSV's in the 5um size today.
GloFo seems to have inherited from AMD the tradition of perennially depending on others ( e,g. IBM ) for device & process technology. This had recently gotten Glo Fo in trouble e,g. in the flip flop regarding gate first or last for HKMG. Turns out IBM's expert advise was not scalable down to 32 nm with consequent yield issues sending AMD to TSMC for Llano.
But now Glo Fo is going after Amkor to develop TSV s. This is indeed a first for Fabs having to depend on OSATs for wafer processing technology ! Such endemic absence of Techno Macho ( which translates into a deep bench to do trouble shooting and the capability to take on process variations - always a plus for Foundries ) might scare off potential customers.