A new sputtering technique named "itshape limited reaction sputtering" is proposed and the feasibility toward an ultra-thin gate insulator is investigated. 5-10 nm thick ZrO2 films were prepared on Si(100) substrates and analyzed by XPS, HR-RBS and RHEED. Significant Zr diffusion into the Si substrate and interface oxidation were not observed. An optimum film was obtained at growth temperature of 300, oxygen flow rate of 4.2% and 500-10 sec RTA. The equivalent oxide thickness of 2 nm was realized with leakage current of 10-7 A/cm2 at 1.5 MV/cm.