Preparation and thermal stability of AlCrTaTiZrV-nitride diffusion barrier layer

doi:10.13251/j.issn.0254-6051.2021.09.039

Abstract

Abstract: The work aimed to study the effect of different nitrogen flow rates on the properties of AlCrTaTiZrV high-entropy alloy nitride films and to examine the thermal stability of (AlCrTaTiZrV)N diffusion barrier layer with a thickness of 15 nm under the optimum nitrogen content. The (AlCrTaTiZrV)N high-entropy alloy nitride films were synthesized by reactive magnetron sputtering under different nitrogen flow. A 15 nm amorphous AlCrTaTiZrVN₁₀ film was prepared on single crystal silicon as a single-layer barrier material for Cu interconnection. A 50 nm-thick Cu film was deposited on the surface of the AlCrTaTiZrVN₁₀ film to obtain the Si/AlCrTaTiZrVN₁₀/Cu film system. To assess its thermal stability, Si/AlCrTaTiZrVN₁₀/Cu structure was annealed at 500 ℃ in high vacuum for various time to simulate real working conditions. The surface morphology, roughness, phase composition and sheet resistance of the specimens were characterized by means of the field emission scanning electron microscopy (FE-SEM), atomic force microscope (AFM), X-ray diffractometer (XRD) and four-point probe (FPP), respectively. The results show that the AlCrTaTiZrV high-entropy alloy thin film is amorphous structure when the nitrogen flow rate is less than 10%. When the nitrogen content is 20%, the high-entropy alloy nitride film presents FCC structure and the crystallinity of the film is improved with the increase of nitrogen content. When the nitrogen flow rate is 10%, the roughness is the lowest of only 0.124 nm. After annealed at 500 ℃ for 8 h, the grain size increases significantly. However, the sheet resistance of the films remain at a low value of 0.070 Ω/□, and no Cu-Si compound is formed. The amorphous structure of 15 nm AlCrTaTiZrVN₁₀ high-entropy alloy nitride film can effectively prevent the diffusion of Cu after annealing at 500 ℃ for 8 h, showing excellent thermal stability and good diffusion barrier properties on Cu.

Key words: high-entropy alloy, diffusion barrier layer, nitride film, amorphous structure, annealing, thermal stability

CLC Number:

TG174.4

Li Rongbin, Li Ke, Jiang Chunxia, Zhang Rulin. Preparation and thermal stability of AlCrTaTiZrV-nitride diffusion barrier layer[J]. Heat Treatment of Metals, 2021, 46(9): 216-222.

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