As previously, the company anticipates a six-to-18 month migration time to this new node. However, there are hurdles that need to be overcome. GlobalFoundries product manager Wei Lii Tan specifically pointed to the requirement of "double patterning requirements and new process rules specific to 20 nm" in a blog post published on Monday. He also mentioned that moving beyond 20 nm will be a "bit more complex".
Double patterning was already demonstrated at the 32 nm node, but it appears that GlobalFoundries will not be able to skip this more expensive manufacturing process at the 20 nm node anymore and will need this approach to overcome the physical limits of 193 nm immersion lithography to create smaller chip structures. "Using double patterning overcomes lithography limitations to fully realize the potential of a 20 nm process by manufacturing alternate tracks of metal in two separate steps," Tan wrote. "Double patterning requires extra masks, along with a colorized layout decomposition process to determine how layout features will be mapped to masks. However, double patterning is primarily needed for lower metal layers, and is not required for every layer."
According to the company, 20 nm equipment is "nearing production readiness", even if "not all semiconductor design companies will be adopting 20 nm immediately".
Update: GlobalFoundries reached out to clarify that it had always accounted for double patterning at 20 nm and, as such, this will not have any affect on the existing roadmap towards that process.