Ultrathin silicon oxynitride film formation by plasma immersion nitrogen implantation

A method is proposed to prepare ultrathin silicon oxynitride films for gate dielectrics used in deep submicron metal-oxide-semiconductor field effect transistor device structures, namely plasma immersion N implantation into S iO2 films. Plasma immersion implantation pulse voltages in the range 200-10 00 V, and fluences from 10(16) to 10(17) N cm(-2) were implanted into therm ally grown SiO2 films, with thicknesses between 3 and 6 nm. The areal densi ties of N and O in the resulting oxynitride films were determined by nuclea r reaction analysis, before and after annealing in high-vacuum. N, O, and S i profiles in the films were determined with subnanometric depth resolution by medium energy ion scattering. The results indicate that plasma immersio n ion implantation allows for shallow and controlled deposition of signific ant amounts of nitrogen (up to 3.8 nm of equivalent Si3N4 thickness). Impla ntation is accompanied by moderate damage at the oxynitride/Si interface wh ich can be recovered by thermal annealing. (C) 1999 American Institute of P hysics. [S0003-6951(99)01706-4].