Surface wettabiliy of nitrogen plasma-implanted silicon

Silicon wafers were implanted with nitrogen by plasma immersion ion implantation (PIII) to alter the surface hydrophilic properties and wettability. Our X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and contact angle measurements indicate that the Si–N bonds formed during the plasma implantation process are the main reason for the enhancement of wettability. The phenomenon can be explained in terms of the surface energy determined from our contact angle measurements. Owing to the non-UHV (ultrahigh vacuum) conditions inherent to most PIII instruments, there is competition between the formation of surface Si–O and Si–N bonds and the nitrogen retained dose is crucial to the final wettability of the plasma treated silicon wafers.