Technique for manufacturing semiconductor devices comprising transistors with different threshold voltages

Abstract

When forming semiconductor devices including transistors with different threshold voltages, the different threshold voltages of transistors of the same conductivity type are substantially defined by performing different halo implantations. As the other implantations performed typically in the same manufacturing step, such as pre-amorphization, source and drain extension implantation and extra diffusion engineering implantations, may be identical for different threshold voltages, these implantations, in addition to a common halo base implantation, may be performed for all transistors of the same conductivity type in a common implantation sequence. Higher threshold voltages of specific transistors may be subsequently achieved by an additional low-dose halo implantation while the other transistors are covered by a resist mask. Thus, the amount of atoms of the implant species in the required resist masks is reduced so that removal of the resist masks is facilitated. Furthermore, the number of implantation steps is decreased compared to conventional manufacturing processes.