Rapid thermal diffusion of boron and phosphorus into silicon using solid diffusion sources

Abstract

Shallow $p^+$-n junctions on the order of $0.1 \mu m$ deep have been fabricated using boron-nitride solid diffusion sources. The process combines the hydrogen injection method and rapid thermal processing. Sheet resistances, in ranges from 50 to $130 \Omega$/sq with junction depths from 0.1 to $0.19 \mu m$, are possible with this technique. $p^+$-n diode characteristics of $0.11 \mu m$ junctions show low reverse leakage current of the order of $10 nA/cm^2$ and the ideality factor of 1.02 for forward bias, indicating the possibility of this method to form PMOS source/drain contacts. Shallow phosphorus $n^+$-p junctions have also been fabricated by rapid thermal processing using the planar diffusion source PH 1000N. Phosphors junctions with sheet resistances in ranges from 34 to $102 \Omega$/sq can be achieved with junction depths from 0.12 to $0.22 \mu m$. The phosphorus $n^+$-p junction diode fabricated with this technique have shown somewhat inferior characteristics in comparison with implanted arsenic junction diodes, showing the reverse leakage current of about $100 nA/cm^2$. However, the process is considered applicable to the NMOS source/drain contacts.