Strontium niobate high- k dielectrics: Film deposition and material properties

Abstract

Strontium niobate ultrathin films were processed by water-based chemical solution deposition, an approach that offers environmental benefits. SrNb 2O 6 and Sr 2Nb 2O 7 show high- k values, which is important for applications such as alternative gate dielectrics. The study of ultrathin films (thickness <30 nm) is crucial, as this is the thickness range for the application envisaged, and as film properties depend strongly on the film thickness. SrNb 2O 6 had a lower crystallization temperature, less interfacial silicate, lower carbonate content, and higher roughness compared to Sr 2Nb 2O 7. The k values of amorphous films were limited for both compositions ( k = 12–14). Crystallization and complete removal of organics or carbonates were accomplished by high-temperature annealing, but increased the roughness and leakage current. For Sr 2Nb 2O 7, interfacial silicates were formed as well. Intermediate calcination steps improved the surface smoothness and increased the k value of SrNb 2O 6 up to 30.