Atomic-scale silicidation of low resistivity Ni -Si system through in-situ TEM investigation

Nickel silicide has many advantages, such as low resistivity and low formation temperature; therefore, it has been widely used in the fields of solar cells, transistors and complementary metal-oxidesemiconductor (CMOS) devices. To obtain high-quality nickel-silicide thin film, solid-state reaction is a convenient and efficient fabrication method. For better understanding of the dynamic formation mechanism, we used in-situ transmission electron microscopy (TEM) to record the diffusion behavior during the heating process. In this work, three-steps annealing process to synthesize different nickel silicides corresponding to the various formation temperatures were investigated systematically. At 250 degrees C, the product of the first-step annealing was inverted-triangle Ni2Si, embedded in the Si substrate. Then, well-distributed NiSi thin film was synthesized, having the lowest resistivity among Ni-Si system at 400 degrees C. Finally, NiSi2, a Si-rich product, would form during the third-step annealing at 600 degrees C. NiSi2 product and Si substrate have small lattice mismatch; thus, the epitaxial relationship would be observed. We provide the evidence of diffusion behaviors and structural identification of Ni-Si system. Furthermore, these results are beneficial for the formation of specific nickel silicides, which is expected to optimize the fabrication of microelectronics.

Automated summary

Nickel silicide, with its low resistivity and low formation temperature, has been widely used in various microelectronic devices. Through a three-step annealing process and in-situ TEM observation, different nickel silicides corresponding to various formation temperatures were successfully synthesized for optimizing the fabrication of microelectronics.