Cu thin films have been deposited on Si (100) substrate by using a non-mass-separated ion beam deposition (IBD) system. The effect of the substrate bias voltage on the properties of the deposited films was investigated using X-ray diffraction, resistivity measurement and field emission scanning electron microscopy. In the case of Cu thin films deposited without bias voltage, a columnar structure and small grains were observed distinctly, and the electrical resistivity of the deposited Cu films was very high. By increasing the bias voltage, no clear columnar structure and grain boundary were observed. The resistivity of Cu films decreased remarkably and at a bias voltage of −50 V, reaching a minimum value of 18 ± 1 n m, which is close to that of the bulk phase (16.7 n m.)

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Ta/Si (100) and Cu/Ta/Si (100) film structures were fabricated by using ion beam deposition with a modified RF sputter-type ion source, in which a strong RF discharge was introduced in order to enhance the plasma density. For Ta/Si structures, Ta films were deposited at various bias voltages. When the substrate bias voltage was not applied, the Ta film showed a columnar structure and had a high resistivity of 2600 n m. On the other hand, when the substrate bias voltage of −50-−200 V was applied, the cross-sectional observation did not show columnar structure at all. In this case, film deposition was considered to be sufficient migration energy by the accelerated Ta + ions. In particular, Ta films deposited at a bias voltage of −125 V had a very small resistivity of 360 n m. Thermal stability of Cu(100 nm)/Ta(50 nm)/Si films, where Ta plays a role of diffusion barrier, was evaluated after annealing in H 2 atmosphere for 60 min at various temperatures. Non-columnar structure Ta films deposited at substrate bias voltages of −50 V and −125 V were found to be stable up to 600 • C, while columnar structure Ta films deposited at zero bias voltage degraded at 300 • C. This result indicates that the thermal stability of the Ta films is mainly governed by the film microstructure of the deposited layer.

Abstrucf-High purity RF-sputter type metal ion source has been developed for non-mass separated ion beam deposition. Fe or Cu rod target of purity 99.999 YO or 99.9999%, respectively, was DC-sputtered inside an RF inductively generated Ar plasma. Optical emission specfroscopy from the plasma region (Fe case) indicated that emission from Fe* becomes larger than that of Ar* when DC bias voltage of -1 kV was applied. This result agreed with our previous mass spectroscopic that Fe+ ion intensity overcomes that of Ar+ because of an efficient Penning ionization of sputtered and evaporated Fe particles. Cu f h s deposited on Si substrate at RT with the ion source showed noncolumnar structure at a substrate bias voltage of -150 V, whereas only columnar structure was obtained with no bias voltage. This tendency qualitatively agreed with the case of Fe fdm formation obtained in our mass separated IBD.

A high-rate sputtering apparatus designed for ion-based film formation was made on an experimental basis. A dense plasma of the order of 1012 cm−3 was generated between the target and the substrate of a dc diode sputtering apparatus by means of an L-coupled high-frequency discharge. When a Cu target was used, the Cu+ ion current in the mass spectrum of the extracted ion beam increased with the Ar gas pressure, and had a maximum value about ten times that of an Ar+ ion current, at a pressure of ∼1×10−1 Torr (1.3×101 Pa). The plasma potential varied continuously from +20 to +200 V when the bias resistance for the high-frequency coil was changed from 10 kΩ to 0. The energy of the ions impinging on the substrate was changed greatly by the change in the plasma potential. The fine structure of the film formed was markedly influenced by the discharge gas pressure and/or the plasma potential. Even ferromagnetic material could be sputtered at a high rate.