Atomic layer deposition of transition metal chalcogenide TaSx using Ta[N(CH3)2]3[NC(CH3)3] precursor and H2S plasma.

As a transition metal chalcogenide, tantalum sulfide ( TaS x ) is of interest for semiconductor device applications, for example, as a diffusion barrier in Cu interconnects. For deposition of ultrathin nanolayers in such demanding 3D structures, a synthesis method with optimal control is required, and therefore, an atomic layer deposition (ALD) process for TaS x was developed. ALD using (tert)-butylimidotris(dimethylamido)tantalum (Ta [ N (CH 3) 2 ] 3 [ NC (CH 3) 3 ]) as the precursor and an H 2 S-based plasma as the coreactant results in linear growth of TaS x films as a function of the number of cycles for all temperatures in the range 150–400 ° C with growth per cycle values between 1.17 ± 0.03 Å and 0.87 ± 0.08 Å. Saturation of the precursor and plasma dose times, established at 300 ° C, was reached after 20 and 10 s, respectively. Variation of the table temperature or the plasma composition offers the possibility to tune the film properties. At 300 ° C, amorphous TaS 3 films were grown, while addition of H 2 to the plasma led to polycrystalline TaS 2 films. The difference in sulfur content in the films correlates to a change in resistivity, where the least resistive film had the lowest S content. [ABSTRACT FROM AUTHOR]