Al2O3-HfO2 mixed high-k dielectrics for MIM decoupling capacitors in the BEOL

An experimental study of MIM decoupling capacitors placed in the BEOL of 300mm wafers using Al2O3 within HfO2 dielectric thin films is reported. By increasing aluminum concentration (7.9%-14.3%) within the dielectric insulator, a capacitance density of up to 27.6 fF/µm2 with linearity of 1610 ppm/(MV/cm)2 at 10kHz was achieved. J-E and dielectric breakdown characteristics at temperatures from -50°C to +150°C were analyzed. Low leakage current (<0.1µA/cm2) was measured for up to 100°C. Further, time-dependent dielectric breakdown reliability measurements under constant field stress were investigated over temperature (25-150°C). Capacitors reached 1000 years of extrapolated lifetime for all Al concentrations (7.9%-14.3%) at 25°C.