Dual work function metal gate CMOS technology using metal interdiffusion

In this letter, we propose a new metal-gate CMOS technology that uses a combination of two metals to achieve low threshold voltages for both n- and p-MOSFET's. One of the gate electrodes is formed by metal interdiffusion so that no metal has to be etched away from the gate dielectric surface. Consequently, this process does not disturb the delicate thin gate dielectric and preserves its uniformity and integrity. This new technology is demonstrated for the Ti-Ni metal combination that produces gate electrodes with 3.9 eV and 5.3 eV work functions for n-MOS and p-MOS devices respectively.