Improvement of Ta Barrier Film Properties in Cu Interconnection by Using a Non-mass Separated Ion Beam Deposition Method

Abstract

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.

Influence of Substrate Bias Voltage on the Impurity Concentrations in Hf Films Deposited by Ion Beam Deposition Method

“…Thus, a strong (002) texture (I ð002Þ =I ð100Þ ¼ 47:62) is obtained in these samples at deposited V s ¼ À50 V. Further, at deposited V s ¼ À100 V, the Hf(002) peak becomes weaken. This change coincides with the results reported by Lim et al 8) about the effect of a substrate bias voltage on the Ta films. Therefore, application of a substrate bias voltage during the deposition process plays an important role in the crystallo-graphic texture of Hf films.…”

Formation of Ultrasmooth and Highly Stable Copper Surfaces through Annealing and Self-Assembly of Organic Monolayers

“…The 28 day and 50 day induction periods prior to the formation of Cu(OH) 2 and CuO layers, respectively, in the annealed Cu samples were significantly longer than earlier observations. ,,− A possible explanation of these differences could be attributed to different morphologies and/or additional surface properties of the Cu surfaces. A detailed explanation of these differences will follow later in this section, after the presentation of the essential (complementary) results on the time dependence of individual oxide overlayer thicknesses as well as the overall oxide composite thickness.…”

Effect of substrate bias voltage on the texture and microstructure of Cu thin films deposited by ion beam deposition

“…Therefore, we fabricated Cu/Ta/Si structures inserting a Ta diffusion barrier, and investigated the thermal annealing effect on I (111) /I (200) for the Cu (100 nm)/Ta (50 nm)/Si (100) structures. Ta diffusion barriers were deposited on Si (100) substrates at Vs = −50 V, which were used to prepare β-Ta films with no columnar structure, an electrical resistivity of 130 mW cm, and of a smooth surface in our previous study [6]. Figs.…”

“…The non-mass separated IBD system with a modified RF sputter-type ion source has already been described elsewhere [6,7]. Two sets of ion sources, composed of RF (13.56 MHz) Cu coils and Cu target (99.9999 %, rod shape, 8 mm in diameter) or Ta target (99.99 %, rod shape, 10 mm in diameter), are located in the deposition chamber (base pressure of 10 -5 Pa).…”