Influence of Dose on the Property of Cobalt Silicides in Source/Drain Area

Abstract

As and BFdopants are implanted for the formation of source/drain with dose of 110 ions/∼510 ions/ then formed cobalt disilicide with Co/Ti deposition and doubly rapid thermal annealing. Appropriate ion implantation and cobalt salicide process are employed to meet the sub-0.13 CMOS devices. We investigated the process results of sheet resistance, dopant redistribution, and surface-interface microstructure with a four-point probe, a secondary ion mass spectroscope(SIMS), a scanning probe microscope (SPM), and a cross sectional transmission electron microscope(TEM), respectively. Sheet resistance increased to 8%∼12% as dose increased in and , while sheet resistance uniformity showed very little variation. SIMS depth profiling revealed that the diffusion of As and B was enhanced as dose increased in and . The surface roughness of root mean square(RMS) values measured by a SPM decreased as dose increased in , while little variation was observed in . Cross sectional TEM images showed that the spikes of 30 nm∼50 nm-depth were formed at the interfaces of / and /, which indicate the possible leakage current source. Our result implied that Co/Ti cobalt salicide was compatible with high dose sub-0.13 process.