CMOS FinFET structures including work-function materials having different proportions of crystalline orientations and methods of forming the same

A method includes forming a first transistor, which includes forming a first gate dielectric layer over a first channel region in a substrate and forming a first work-function layer over the first gate dielectric layer, wherein forming the first work-function layer includes depositing a work-function material using first process conditions to form the work-function material having a first proportion of different crystalline orientations and forming a second transistor, which includes forming a second gate dielectric layer over a second channel region in the substrate and forming a second work-function layer over the second gate dielectric layer, wherein forming the second work-function layer includes depositing the work-function material using second process conditions to form the work-function material having a second proportion of different crystalline orientations.