Pulsed laser deposition of zirconium silicate thin films as candidate gate dielectrics

Abstract

Thin films of zirconium silicate ZrxSi1-xO2 (with x = 0.69), a material that has been suggested as a possible high-k dielectric, are deposited on silicon wafers by pulsed laser deposition (PLD) under different deposition and postannealing conditions. The morphology and electrical properties of these films are characterized. It is shown that the films remain amorphous after an ex situ rapid thermal annealing (RTA) at temperatures as high as 800degreesC. For the similar to 6 nm thick film deposited at 300degreesC in an O-2 ambient with a N-2 ambient post-RTA at 500degreesC for 5 min, the equivalent oxide thickness (EOT) is similar to 1.9 nm, as evaluated from capacitance-voltage ( C - V) measurements. The samples prepared with the N-2 ambient post-RTA show a slightly higher leakage current than that for samples annealed in the O-2 ambient. For the films deposited in N-2, the smallest EOT of similar to 1.1 nm is obtained, and the films have fair electrical properties in spite of the high interface state density and relatively higher leakage.