SERIES RESISTANCE OF SELF-ALIGNED SILICIDED SOURCE DRAIN STRUCTURE

Abstract

The external resistance of the self-aligned silicided source/drain structure is examined by two-dimensional simulation considering recession of the contact interface due to the consumption of silicon during the silicidation process. It is observed that the recessed contact interface forces a significant amount of current to flow into the high-resistivity part of the junction resulting in an increase of resistance as large as several hundred ohms-micrometers in comparison with the surface contact structure. The increase scales up with the scale-down of the minimum feature size, and the expected benefits of the SALICIDE structure become diminished for the sub-half-micrometer devices. A simple analytical explanation is proposed. The error between the analytical calculation and the two-dimensional simulation is within 20%. By considering the recession of the contact interface, the reported high external resistance of the short-channel MOSFET's is explained successfully. Different source/drain contact types are compared, and it is concluded that the conventional SALICIDE process should be modified for the sub-half-micrometer devices.