Characterization of Defect Formation during Ni Silicidation for CMOS Device Application

Abstract

Low resistance metal silicides are widely used in advanced CMOS device as contact and interconnect materials. As device feature size shrinks, Ni silicides are widely used to replace Co silicides due to lower resistivity and ability to silicide narrower feature size (<4nm). During silicide formation, crystallization of the Ni silicide phase is controlled by Ni diffusion upon annealing since Ni is the diffusing species. First, Ni forms Ni 2 Si during annealing at 300ºC, then NiSi is formed at 250ºC and all of the deposited Ni is consumed. NiSi is the desired phase for CMOS device application because it has the lowest sheet resistance among Ni-based silicides. Finally, NiSi 2 is formed at higher temperatures of around 800ºC [1].

Intrinsic nanofilamentation in resistive switching

“…Such needle-shaped Ni defects due to metal diffusion along (111) planes have also been reported as a "process issue" in the conventional NiSi-based CMOS process for the 10 nm technology node. 33 From a physical analysis perspective, the Ni in the silicon substrate forms a good marker indicating the location of the nanofilament inside the dielectric. The EDX line profiles of various elements of interest were further collected from the center of the filament (solid line) and the intact area (dashed line), as shown in Fig.…”

Phase State Analysis of Nickel Silicides in Complementary Metal–Oxide–Semiconductor Device Using Plasmon Energy Map

“…Many studies have been performed to elucidate the phase states of nickel silicides in nanometer areas using scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) and energy-filtering transmission electron microscopy (EF-TEM). [12][13][14] STEM-EELS obtains spectra at different positions of a specimen continuously, using a small electron probe and is an effective method for obtaining chemical bond information with high spatial resolution. 15) For example, previous studies have obtained low-loss spectra that were dominated by collective excitations known as plasmon and core-loss spectra, which correspond to excitation of inner shell electrons known as ionization edges, of NiSi 2 , NiSi, and Ni 2 Si.…”

Transmission electron microscopy assessment of conductive-filament formation in Ni–HfO2–Si resistive-switching operational devices

“…In the literature, similar diffusion processes of Ni into the Si substrate 26) and also the migration of the Si from the substrate to the dielectric layer [28][29][30] are observed in dielectric stacks. Additionally, several authors 12,13) have described the migration of the Ni from the electrode through the HfO 2 layer and into the Si substrate as a typical mechanism in the ReRAM on HfO 2 devices.…”

“…In the literature, other defects in CMOS devices due to the diffusion of Ni towards the Si substrate are observed. 26,27) To rule out any influence of the Ni removal process in the obtained results, a TEM lamella of an HDB sample with an intact Ni electrode was prepared using an FIB, by cutting the whole device slice-by-slice and conducting SEM simultaneously until evidence of the dielectric rupture became visible. Figure S5 in the online supplementary data at http:// stacks.iop.org/APEX/11/014101/mmedia displays the obtained TEM and EELS results.…”