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 (TaSx) 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 TaSx was developed. ALD using (tert)-butylimidotris(dimethylamido)tantalum (Ta[N(CH3)(2)]3[NC(CH3)(3)]) as the precursor and an H2S-based plasma as the coreactant results in linear growth of TaSx films as a function of the number of cycles for all temperatures in the range 150-400 degrees C with growth per cycle values between 1.17 +/- 0.03 & Aring; and 0.87 +/- 0.08 & Aring;. Saturation of the precursor and plasma dose times, established at 300 degrees 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 degrees C, amorphous TaS3 films were grown, while addition of H-2 to the plasma led to polycrystalline TaS2 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.