Effects of nitridation of silicon and repeated spike heating on the electrical properties of SrTiO3 gate dielectrics

Abstract

Electrical properties of SrTiO 3 (STO) gate dielectrics on Si substrates grown by rf-magnetron sputtering were studied. We employed the surface nitridation and repeated spike heating to improve the interfacial properties of STO/Si. The nitrogen was moderately incorporated at the interface by first growing a thin SiON layer and then removing this sacrificial layer before growing STO gate dielectric. The experimental results indicate that this nitridation treatment may retard the formation of thin interfacial layer during the high-temperature growth of STO gate dielectric and consequently decrease the equivalent oxide thickness (EOT) by about 10% toward 24% at various deposition pressures. The STO gate dielectric with this nitridation treatment exhibited slightly lower leakage current at an accumulation region and nearly 2 orders of magnitude lower leakage current at an inversion region. The repeated spike heating technique was also employed to deposit a STO gate dielectric at repeated oscillating temperatures. The results show that this thermal treatment reduced the interfacial trap states and the leakage current was also reduced by about 1 order of magnitude at the same EOT.