Complex High-κ Oxides for Gate Dielectric Applications

Gate dielectrics with enhanced capacitance density and small current leakage are critical for continuous scaling of electronic devices. Enhanced capacitance and suppressed current leakage, however, rarely occur simultaneously. Hafnium zirconate, hafnium aluminate and zirconium aluminate thin films are grown on silicon and indium phosphide using plasma-enhanced atomic layer deposition. The metal-oxide-semiconductor capacitor devices are fabricated to study dielectric properties, device performance and semiconductor-gate dielectric interfacial quality. All the devices show very low density of interfacial traps. Hafnium zirconate shows an ultra-low D it of 2.61 × 10 10 cm −2 eV −1 and 8.62 × 10 11 cm −2 eV −1 on silicon and indium phosphide, respectively, due to very low growth temperature (100°C) during growth and high post-fabrication heat treatment temperature (510°C). The ultra-low density of interfacial traps suggests a reliable cohesion between the high-κ complex oxide and semiconductor. The hafnium zirconate also shows the highest capacitance density and, interestingly, the lowest leakage current.