Mechanism of Improved Thermal Stability of Cobalt Silicide Formed on Polysilicon Gate by Nitrogen Implantation

概要

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It is found that the thermal stability of CoSi_2 films is improved by N^+_2 implantation (I/I) because the grain size of CoSi_2 films with N^+_2 I/I is much smaller than that without N^+_2 I/I. Rutherford backscattering spectrometry (RBS) and Auger electron spectroscopy (AES) analyses show that the nucleation of CoSi_2 transformation from CoSi is suppressed by N^+_2 I/I. The nucleation temperature for the sample with 5 × 10^<15> cm^<-2> N^+_2 I/I is about 25℃ higher than that without N^+_2 I/I. Since the nucleation temperature is increased, CoSi_2 films are formed incompletely at the as-formed state; thus, CoSi_2 has small grain size. As a result, the thermal stability of CoSi_2 films is significantly improved by N^+_2 I/I due to the small grain size of CoSi_2.
社団法人応用物理学会の論文
1998-11-15