Flexible integration of logic blocks with transistors of different threshold voltages

Abstract

An integrated circuit constructed according to an arrangement of logic blocks, with one or more logic blocks including transistors of a different threshold voltage than in other logic blocks. Spacing between neighboring active regions of different threshold voltages is minimized by constraining the angle of implant for the threshold adjust implant, and by constraining the thickness of the mask layer used with that implant. These constraints ensure adequate implant of dopant into the channel region while blocking the implant into channel regions not subject to the threshold adjust, while avoiding shadowing from the mask layer. Efficiency is attained by constraining the direction of implant to substantially perpendicular to the run of the gate electrodes in the implanted regions.