Patent ID: 8580692

Claim:
A method for formation of a fin field effect transistor (FinFET) device, the method comprising: forming a mandrel mask and a large feature (FX) mask on a metal hardmask layer of a film stack, the film stack comprising a silicon on insulator (SOI) layer located underneath the metal hardmask layer and an amorphous carbon layer located on top of the metal hardmask layer, wherein forming the mandrel mask and the FX mask comprises: etching the amorphous carbon layer to form a plurality of mandrels on the metal hardmask layer; depositing a sidewall image transfer (SIT) spacer layer over the plurality of mandrels and on the metal hardmask layer; performing etchback of the SIT spacer layer to expose top surfaces of the plurality of mandrels; and removing the plurality of mandrels, wherein a portion of the SIT spacer layer that remains on the metal hardmask layer comprises the mandrel mask; etching the mandrel mask and the FX mask simultaneously into the metal hardmask layer; and etching the mandrel mask and the FX mask into the SOI layer using the etched metal hardmask layer as a mask.