The semiconductor-dielectric interface is of key importance to the performance of Metal-Oxide-Semiconductor transistors (MOSFETs). The near-surface Photoconductance Decay (ns-PCD) method using probe contacts is shown in this study to be very useful in measuring effective carrier lifetime at the semiconductor-dielectric interface. By doing so, it provides direct information on the condition of the charge transport environment in the MOSFET channel without a need to fabricate a transistor. The way measurement is implemented depends on the thickness of dielectric. For dielectric layers thicker than about 5 nm, etched windows in the dielectric layer are necessary to achieve an ohmic contact with the semiconductor layer. For dielectric layers thinner than about 5 nm, however, the ohmic contact to the semiconductor substrate, essential to the performance of this measurement, is established using probes and electrical contact formation process. The measurements were performed on thermally oxidized Si-SiO2 structures as well as Si-Al2O3 (3 nm) and Si-Ta2O5 (3 nm) structures formed by means of Atomic Layer Deposition (ALD). The results obtained demonstrate that the PCD method adapted as discussed in this work can be very useful in monitoring condition of semiconductor-ultra-thin (<5 nm) dielectric interface by measuring carrier lifetime in the as-processed samples, i.e. without subjecting it to any processing step beyond dielectric deposition.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry