A method includes: providing a substrate; forming a first pair of source/drain regions in the substrate; disposing an interlayer dielectric layer over the substrate, the interlayer dielectric layer having a first trench between the first pair of source/drain regions; depositing a dielectric layer in the first trench; depositing a barrier layer over the dielectric layer; performing an operation on the substrate; removing the barrier layer from the first trench to expose the dielectric layer subsequent to the operation; and depositing a work function layer over the dielectric layer in the first trench.