Atomic-Layer-Deposited Aluminum Oxide (Al ₂ O ₃ ) as a Barrier for Local Oxidation of Silicon

The LOCal Oxidation of Silicon (LOCOS) is a widely used technological process that conventionally exploits hundreds-of-nanometer-thick silicon nitride (SiN) layers as the mask to locally prevent the silicon surface to be oxidized. Here, investigations of the use of ultrathin (<20 nm) Al2O3 layers grown by atomic layer deposition (ALD) as material-sparing alternative to SiN are reported. A significant reduction of the oxidation rate by a factor greater than 15 is demonstrated for either dry thermal and plasma oxidations, paving the way toward more environmentally sustainable LOCOS processes for the fabrication of microelectronic and photonic devices.