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 n ew doping method called rapid vapor-phase direct doping which is suita ble for making shallow junctions of less than 50 nm. An atmospheric pr essure CVD system is used for the experiments and, in this process, bo ron atoms are doped into Si from the vapor phase after the native oxid e is removed in hydrogen. From the results obtained for time dependenc e 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 bo ron atoms. This unique characteristic is the reason why shallow juncti ons can be formed as confirmed by the simulation. The boron-doping eff iciency increases drastically after the boron concentration on the Si surface exceeds solid solubility. This indicates that when the Si surf ace is covered with boron, the boron atoms which dissociated from B2H6 gas may adsorb on the surface easily