Low Temperature Deposition of TiN Diffusion Barrier Metal for Integrated Circuit by Low Frequency Plasma CVD

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Titanium nitride (TiN) films have been used in the fabrication of integrated circuits as a diffusion barrier layer metal. Usually, TiN films are produced by deposition with thermal chemical vapor deposition (CVD), plasma CVD and physical vapor deposition or plasma spraying methods. However, these methods require high-temperature (>600℃) substrates to achieve the depositions, which sometimes causes thermal damage to the deposited films. At temperatures above 550℃, thermal diffusion of materials not suitable for semiconductor devices may also occur. Therefore, it is desirable to develop a deposition technique for TiN films using low-temperature (<550℃) substrates to avoid thermal damage. In our previous work, TiN films have been deposited on silicon substrates at low substrate temperature (TィイD2subィエD2) (400℃-550℃) by 50Hz plasma CVD using a TiClィイD24ィエD2+NィイD22ィエD2+HィイD22ィエD2 gas mixture. A substrate bias circuit with two diodes was used to enhance the deposition through ion processes. The Vickers hardness values of the deposited TiN films at TィイD2subィエD2 ranging from 450 to 550℃ were above 2200Hv, and resistively was below 100 μ Ωcm TィイD2subィエD2>500℃. The composition of the deposited films was investigated by the RBS method to determine that the at.% value of the Cl content in the TiN films is about 1% at TィイD2subィエD2=550℃ . XRD spetra revealed that the film has the preferred orientation ofδ -TiN with (200) and (220) under the deposition condition of TィイD2subィエD2>500℃. From these results, it was found that high quality and uniform TiN film was obtained on three-dimensional substrate surface by the 50Hz plasma CVD with a bias circuit using two diodes.