HfO/sub 2/ MIS capacitor with copper gate electrode

Metal-insulator-semiconductor capacitors were fabricated using atomic vapor deposition HfO/sub 2/ dielectric with sputtered copper (Cu) and aluminum (Al) gate electrodes. The counterparts with SiO/sub 2/ dielectric were also fabricated for comparison. Bias-temperature stress and charge-to-breakdown (Q/sub BD/) test were conducted to examine the stability and reliability of these capacitors. In contrast with the high Cu drift rate in an SiO/sub 2/ dielectric, Cu in contact with HfO/sub 2/ seems to be very stable. The HfO/sub 2/ capacitors with a Cu-gate also depict higher capacitance without showing any reliability degradation, compared to the Al-gate counterparts. These results indicate that HfO/sub 2/ with its considerably high density of 9.68 g/cm/sup 3/ is acting as a good barrier to Cu diffusion, and it thus appears feasible to integrate Cu metal with the post-gate-dielectric ultralarge-scale integration manufacturing processes.