Phase and structural evolution of sol-gel synthesized ZrO ₂/Si thin films under heat treatment

ZrO ₂/Si thin films were fabricated using a sol-gel technique, and the chemical state change and structural evolution from sol to gel to Zr oxide by heat treatment were investigated. The precursor sol was synthesized using a Zr-acetylacetonate (Zr-acac) precursor, spin-coated, dried on Si(100) substrates, and then annealed at 300-700 °C in air. With increased annealing temperature of the sol-gelderived layer, Zr-acac decomposed into Zr-acetate, an amorphous ZrO ₂ phase formed, and crystallization into atetragonal phase occurred. In addition, the ZrO ₂ layer became denser and the interfacial layer between ZrO ₂ and Si thickened, whereas the surface morphology was nearly unaffected and remained smooth with root-mean-square values\4.5 Å