Effect of nitrogen flow rate on TaN diffusion barrier layer deposited between a Cu layer and a Si-based substrate. Issue 15 (15th October 2017)

• Record Type: Journal Article
• Authors: Chen, Shih-Fan; Wang, Shea-Jue; Yang, Tzu-Hsien; Yang, Zheng-Da; Bor, Hui-Yun; Wei, Chao-Nan
• Is Part Of: Ceramics international. Volume 43:Issue 15(2017)
• Page Start: 12505
• Page End: 12510
• Publication Date: 2017-10-15
• Subjects: Amorphous -- TaNx -- Barrier layer -- Diffusion -- Copper process -- XRD; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2017.06.122
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: A TaNx layer was deposited as a barrier between Cu and a p-type Si-based substrate. Various N2 flow rates were used during deposition along with a fixed Radio Frequency (RF) power and a fixed Ar-sputtering flow rate. The performance of the various TaNx barrier layers was tested and the optimized parameters for preparation were determined. When using a N2 flow rate of 3.5 sccm and a N2 /Ar ratio of 1:10 followed by annealing at 700 °C the Ta:N ratio of the TaNx barrier was 10:7. The current leakage of the barrier was lower when using a higher N2 flow rate during deposition as this produced an amorphous TaNx thin film, and the electric capacitance was relatively greater on insertion of a TaNx layer as a insulation resistance layer when using a higher N2 flow rate. The surface roughness of the TaNx film, as measured by atomic force microscopy (AFM), slightly increased with increasing N2 flow rate. The aforementioned processing parameters produced a high-quality amorphous TaNx thin-film layer by adjustment of the TaNx -barrier crystallinity. TaNx barriers produced using the various N2 flow rates can prevent the diffusion of Cu atoms to the Si substrate. The calculated initial diffusion coefficient of TaN0.7 annealed at 700 °C, as calculated by Fick's law, was 1.3 × 10 −5 cm 2 /s. X-ray diffraction (XRD) analysis indicated that no Cu-Si compounds were present in the TaN0.7 layer prepared using a 3.5 sccm N2 flow rate and a N2 /Ar ratio of 1:10 followed by annealing at 700 °C.