Atomic Layer Deposition of Al-Doped ZrO2 Thin Films as Gate Dielectric for In0.53Ga0.47As

We have investigated the atomic layer deposition (ALD) on SiO2 and III-V (i.e., In0.53Ga0.47As) substrates of Al-doped ZrO2 (Al- ZrO2) films. The aim is to benefit from trimethylaluminum-based chemistry as adopted in the ALD of Al2O3 while concomitantly obtaining an improvement in the value of the dielectric constant of the gate stack. An in situ monitoring of the process with spectroscopic ellipsometry was carried out in order to address the formation of the first few monolayers of the films. The correlation with the structural and chemical characterization provides insights about the interface composition upon ALD. A k value of 19 ± 2 is demonstrated for Al-ZrO2 films deposited on SiO2. The electrical performances of capacitors fabricated on In0.53Ga0.47As including Al-ZrO2 as gate dielectric exhibit encouraging properties compared to those acquired for Al2O3. However, a further optimization of the interface reactivity in order to prevent the formation of undesired In, Ga and As oxidized species appears still needed for the combination of the Al2O3 and ZrO2 ALD processes.