Al2O3/Si3N4 stacked insulators for 0.1 μm gate metal-oxide-semiconductor transistors realized by high-density Si3N4 buffer layers

We developed Al2O3 / Si3N4 stacked insulators suitable for the advanced metal - oxide semiconductor (MOS) devices. Ultrathin Si3N4 was prepared by direct nitridation of Si substrate using atomic nitrogen radicals. With this process, the film obtained was less defective compared to conventional Si3N4. Al2O3 was then deposited by atomic layer deposition on Si3N4 and oxidized to eliminate defects in the film. Since the buffer Si3N4 does not contain a large amount of hydrogen, we could perform high- temperature oxidation without any additional interfacial layer formation in the Si substrate. We achieved high capacitance density and low leakage current that are acceptable for the gate insulator in advanced MOS devices with a 0.1 mum gate length by exploiting this buffering technique. (C) 2003 American Institute of Physics.