Guess it was an expansion not a new plant. See below.

NEC Electronics America Inc. announced today it has hired 60 employees for its recently expanded semiconductor manufacturing operations in Roseville, Calif., where it recently added a line capable of fabricating eight-inch wafers using a 0.15-micron process to complement its existing line, which is used to fabricate six-inch wafers with 0.35- and 0.25-micron processes. Opty