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This work concentrates on the diffusion barrier stability of very thin (10 or 20 nm) α- or β-Ta, TaN, Ta(O) and Ta(N,O) films in the Cu/barrier/Si system. Based on the classical theory of the thin film growth and know how of material transport in thin films, the various Ta-based films were classified according to their density of free short-circuit paths. Using scanning electron microscopy, transmission electron microscopy, glow discharge optical emission spectroscopy and secondary ion mass spectrometry, the 20 nm thin polycrystalline columnar-structured β-Ta films were found to be stable up to 500 °C for 1 h. After 1 h at 600 °C Cu3Si was formed due to short-circuit diffusion of Cu throughout the β-Ta films. The 20 nm thin giant-grained α-Ta films show equivalent performance to the β-Ta films. On the other hand, the 10 nm thin stuffed nanocrystalline face-centered-cubic (fcc) TaN films were able to protect the Si from Cu diffusion up to at least 600 °C/1 h. Ten nm thin amorphous-like Ta(N,O) and Ta(O) films also show barrier stability that is comparable to fcc TaN. While Ta(N,O) tends to recrystallize mainly into hexagonal-close-packed Ta2N above 500 °C, the Ta(O) remains amorphous even at 600 °C. Besides the amorphous-like microstructure, the high recrystallization temperature of Ta(O) is the reason why the introduction of 5 nm thin Ta(O) film into the Cu/5 nm Ta(O)/5 nm β-Ta/Si structure leads to a stability increase up to at least 600 °C for 1 h.

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This paper presents the resufb on the patterning of shalfow french isolation for the 70nm DRAM technology node on 300mm wafers. Using a new friple hard mask approach incorporating a carbon plm patterns with 70nm CD and STI depth of abaut 250nm could be achieved. Keywords

In this paper the investigation of r.f.‐sputter‐deposited Ta, Ta‐N and Ta‐N‐O thin films is presented. Using atomic force microscopy in combination with sheet resistance measurements, Auger electron spectroscopy and x‐ray diffraction, the thin film properties and microstructure are examined. Two crystalline modifications of Ta (tetragonal β‐Ta and bcc α‐Ta) are reported. By incorporation of nitrogen and/or oxygen into the Ta films, nanocrystalline and quasi‐amorphous structures can be achieved. Finally, the usefulness of the films as diffusion barriers in Cu‐based metallization systems is described.© 1997 John Wiley & Sons, Ltd.