p - type metal - oxide semiconductor field effect transistor devices have a characteristic property known as threshold voltage . this threshold voltage may consist of separate threshold voltages associated with the main portion of the gate region of the device and with the sidewall corner of the device . under some conditions , the threshold behavior in the sidewall corner region of the device may dominate the performance of the device , not necessarily in the manner intended by the designer of the device . a method of controlling threshold voltage behavior is described . in particular , ion implantation of nitrogen in the gate sidewall region of the device can provide such control . devices made by this method are also described .