SemiconductorsMove could secure American access to older chips amid China aggressionGlobalFoundries and UMC each control around 5% of the global market for contract chipmaking. (Photos by Reuters)TAIPEI -- U.S. contract chipmaker GlobalFoundries and United Microelectronics Corp., Taiwan's No. 2 chipmaker, are exploring the possibility of a merger amid American efforts to mitigate risks surrounding the Taiwan Strait and fend off growing competition from China in mature chips, Nikkei Asia has lear...