In-situ surface preparation of InP-based semiconductors prior to direct UVCVD silicon nitride deposition for passivation purposes

To improve the passivation quality on InP and its related compounds, an in-situ soft predeposition surface preparation using an appropriate chemistry proves to be useful. Two different surface treatments prior to direct UV-assisted silicon nitride deposition have been tested, namely UV-excited ammonia gas and xenon difluoride vapour, and applied to InP, InGaAs and AlInAs semiconductors. To evaluate the influence of these two treatments on the electrical characteristics of III-V compounds, metal insulator semiconductor (MIS) diodes were fabricated on InP and InGaAs and the interface trap density was deduced from C(V) analysis. As for AlInAs, simple metal semiconductor metal (MSM) structures were fabricated and the level of surface leakage current was measured. From these measurements, both surface techniques turn out to be beneficial to the electrical characteristics of III-V semiconductors.