Study of low temperature MOCVD deposition of TiN barrier layer for copper diffusion in high aspect ratio through silicon vias

• The MOCVD TiN films are N-riched.
• Plasma treatment changes the films from amorphous to 7 nm crystal grain size.
• The films have larger gap in Ti and N concentration and contain less than 5% carbon.
• The plasma densification lowers the carbon content down to 2%.
• The step coverage is ⩾50% in 10 × 80 μm TSVs sidewall.

This article is related to the development of a new low temperature CVD titanium nitride deposition process for the formation of a copper diffusion barrier in 3D TSV integration, using a metalorganic precursor and NH3.The physicochemical properties of the film are studied on 300 mm silicon wafers deposited using a SPTS Technologies Sigma300 fxP™ deposition equipment. A design of experiments (DoEs) was carried out at 200 °C to check the influence of parameters such as reactor pressure, spacing (distance between the showerhead and the wafer), precursor/NH3 flow rate during deposition and NH3 flow rate during a subsequent densification plasma treatment. Responses including resistivity, uniformity, deposition rate and stress were measured. From this DoE, two process points are chosen according to expected material specifications requested from applications: a low resistivity process and a median conditions process. Then microstructure, the composition and stoichiometry of the film deposited with these process points are studied. Finally, the step coverage and continuity of the barrier in a high aspect ratio “through silicon via” (8:1, 10 μm diameter etched in 80 μm silicon) are measured and compared with a reference I-PVD process.

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