EFFECTS OF BF2+ IMPLANTS ON TITANIUM SILICIDE FORMATION BY RAPID THERMAL ANNEALING

The formation of titanium silicides on Si implanted with different BF2+ dosages has been studied by secondary ion mass spectrometry and transmission electron microscopy measurements. The thickness of the silicide layer formed in the temperature ranging from 600 to 800-degrees-C has been investigated as a function of the implanted BF2+ dosage up to 1 X 10(16) cm-2. Annealing at 700-degrees-C results in conversion of the titanium film into predominantly C49 TiSi2, and most of it is transformed into the C54 phase at 800-degrees-C or higher, resulting in a lower sheet resistance (16-mu-OMEGA cm). The titanium silicide thickness formed after the rapid thermal annealing (RTA) treatment depends on the implanted BF2+ dosage, caused by the native oxide enhanced by increased damage. Boron is redistributed into the silicide layer up to the solid solubility limit during annealing, leading to an accumulation at the silicide/silicon interface. The lowest contact resistance (with a size of 0.7-mu-m X 0.7-mu-m) of 35 OMEGA is obtained at the annealing temperature of 700-degrees-C.