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., In_0.53Ga_0.47As) 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 In_0.53Ga_0.47As 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. [ABSTRACT FROM AUTHOR]