HfO2 MIS capacitor with copper gate electrode

Abstract

Metal-insulator-semiconductor capacitors were fabricated using atomic vapor deposition HfO2 dielectric with sputtered copper (Cu) and aluminum (Al) gate electrodes. The counterparts with SiO2 dielectric were also fabricated for comparison. Bias-temperature stress and charge-to-breakdown (QBD) test were conducted to examine the stability and reliability of these capacitors. In contrast with the high Cu drift rate in an SiO2 dielectric, Cu in contact with HfO2 seems to be very stable. The HfO2 capacitors with a Cu-gate also depict higher capacitance without showing any reliability degradation, compared to the Al-gate counterparts. These results indicate that HfO2 with its considerably high density of 9.68 g/cm(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.