For 20nm, there will be an increase in wafer cost directly attributable to the cost of double patterning. The IBS estimates for early adopters wafer costs across nodes is shown below.
Prior to 20nm, wafer prices trended to approximately a 25% per node increase. Starting at 20nm, that increase jumps to around 60% per node. Most of this increase comes from the extra process steps required to do double masking and etching, as well as the double patterning software the fabs will have to use in mask preparation.
At 20nm, designers will also be required to purchase new double patterning software, and do additional work in the design layout and verification to enable the actual double patterning processes in the fab.
Initial content provided by Mentor Graphics