Selective atomic layer deposition of zirconia on copper patterned silicon substrates using ethanol as oxygen source as well as copper reductant

The authors report a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO₂) on copper patterned silicon surfaces. Instead of using common atomic layer deposition (ALD) oxygen sources such as water, oxygen, or ozone, the authors use ethanol, which serves as oxygen source for the ALD on the silicon side and as effective reducing agent on the copper side, thereby selectively depositing ZrO₂ film on the silicon surface of the substrate without any deposition on copper up to at least 70 ALD cycles. The resulting ZrO₂ nanofilm is found to be an effective copper diffusion barrier at temperatures at least up to 700 °C.