Method of making dense complementary transistors

Abstract

A method is provided for making complementary field effect transistors in a semiconductor layer having a first portion including an N type transistor with a channel region defined by N+ source and drain regions and having a second portion including a P type transistor with a channel region defined by P+ source and drain regions. An insulating layer is disposed over the first and second portions with thin insulating films formed over the channel regions. The steps of the method include applying a masking layer over the insulating layer having an opening over one of the portions, introducing a first impurity into the channel region of the one portion for channel tailoring purposes, depositing a first conductive refractory material on the thin insulating film located over the channel region of the one portion, removing the masking layer, introducing a second impurity into the channel region of the other portion for channel tailoring purposes and depositing a second conductive material on the thin insulating film located over the channel region of the other portion and in contact with the first conductive material. The first and second conductive materials have different work functions. The first conductive material is, preferably, platinum silicide while the second conductive material may be aluminum.