CHARACTERISTICS OF SHALLOW BORON-DOPED LAYERS IN SI BY RAPID VAPOR-PHASE DIRECT DOPING

Characteristics are shown for shallow boron-doped layers formed by a new doping method called rapid vapor-phase direct doping which is suitable for making shallow junctions of less than 50 nm. An atmospheric pressure CVD system is used for the experiments and, in this process, boron atoms are doped into Si from the vapor phase after the native oxide is removed in hydrogen. From the results obtained for time dependence of doping characteristics, the surface boron concentration increases almost proportionally to the doping time. This result means that the surface boron concentration is determined by the amount of supplied boron atoms. This unique characteristic is the reason why shallow junctions can be formed as confirmed by the simulation. The boron-doping efficiency increases drastically after the boron concentration on the Si surface exceeds solid solubility. This indicates that when the Si surface is covered with boron, the boron atoms which dissociated from B2H6 gas may adsorb on the surface easily