Effect of TiN Microstructure on Diffusion Barrier Properties in Cu Metallization

Abstract

The relationship between TiN microstructures and diffusion barrier properties of TiN against Cu was investigated. TiN deposited by a chemical vapor deposition (CVD) method is composed of columnar grains grown normal to the sidewall on the side of the trench. On the other hand, the gram boundaries of sputter-deposited TiN tilt upward from the normal direction to the sidewall, and the tilt angle depends on the sputtering conditions. Voids between TiN grains are observed on the side of the trench and the size of the voids depends on the deposition conditions. In the Cu/CVD-TiN (the upper/lower layer) and Cu/conventional sputtered TiN system, no Cu is detected in surrounding SiO, films, either outside the sidewall or underneath the bottom of the trench after annealing at 400°C for 3 mm. However, in the Cu/long-throw sputtered TiN system, where TiN is composed of columnar grains with void regions between grains, and the tilt angle of the grain boundaries from the normal direction to the sidewall is 27°, some Cu is detected outside the sidewall, even when the TiN thickness on the side of the trench is equal to or thicker than that of CVD-TiN or conventionally sputtered TiN. The diffusion barrier property of TiN in Cu metallization depends on the TiN grain structures rather than on the TiN thickness on the side of the trench. InfroductionCu has been considered as a promising metallization

Ultra-Thin (AlCrTaTiZr)Nx/AlCrTaTiZr Bilayer Structures of High Diffusion Resistance to Cu Metallization

“…However, in academic researches, due to the limit of metrology tools, most of the studies on barrier abilities are performed conventionally by thermal annealing and the subsequent microscopic characterizations of interface reactions and depth-profiling analyses of element accumulations (6)(7)(8)(9)(10)(11)(12)(13)(14). In the present study, although the diffusion resistance of the HEAN x /HEA bilayers is also evaluated by the conventional method, rather than the BTS test, nevertheless, in comparison with other reported barrier layers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), the better performance of the bilayer structures developed herein of a comparable or even smaller thickness and examined under stricter conditions indicates a high potential for their application to diffusion barriers. According to aforementioned observations and analyses, the excellent resistance of the ultra-thin HEAN 0.7 /HEA and HEAN 1 /HEA bilayer structures to Cu diffusion at high temperatures was verified.…”

Impact of the Unique Physical Properties of Copper in Silicon on Characterization of Copper Diffusion Barriers

“…Some groups have applied such analysis techniques as SEM (scanning electron microscopy) and even optical microscopy to detect the first signs of degradation of barrier integrity by appearance of defects on the surface of the barrier layer or the copper film, or appearance of etch pits after chemical removal of the barrier layer and selective etching of silicon (see, e.g., [5,15,18,20,82,99,100,103]). Plan view and cross-sectional TEM analyses (see, e.g., [11,14,19,21,71,93,96,98,101,104]) were used to detect interaction at the interfaces, degradation of the interface sharpness, and formation of spikes of Cu-silicide at the interface, or to measure Cu or Al concentration at different depths of the barrier layers using EDX (energy-dispersive X-ray spectroscopy) [90,99,105].…”

4-nm thick multilayer structure of multi-component (AlCrRuTaTiZr)N as robust diffusion barrier for Cu interconnects

“…Therefore, films of transitions metal nitrides, mainly TiN and TaN, have been developed and extensively used in Al and Cu interconnects, respectively [4,5]. However in the 32 or 22 nm generation of semiconductor manufacturing, a more suitable barrier layer is highly demanded because of the microstructure defects of the conventional barrier materials such as columnar boundaries.…”