At the edge between metal organic chemical vapor deposition and atomic layer deposition: Fast Atomic Sequential Technique, for high throughput conformal deposition

Abstract

A comparison of the metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and a new deposition method, the Fast Atomic Sequential Technique (FAST®), was completed. Within all the materials which can be deposited by the FAST technique, the case study of TiN thin film deposition by reaction of tetrakis(diethylamino)titanium precursor with NH3 reactant gas is presented here. The thickness and resistivity measurements revealed that while the FAST deposition is five times faster than the ALD, the lowest resistivity achieved is four times lower than MOCVD minimum resistivity, thus equivalent to ALD at 100 μΩ cm. Moreover, a 25% gain toward lower action energy of the FAST deposition compared to the MOCVD tends to support a different reaction mechanism between the two techniques. Additionally, the FAST technique introduces new process parameters offering the possibility to change the deposition technique to either a MOCVD-like or to an ALD-like deposition in the same tool, thus allowing to choose between high throughput and high conformality or for a compromise of the two. Then, using high aspect ratio vias, the higher conformality of FAST compared to MOCVD is shown. Evolution of the conformality on different aspect ratios devices shows that while ALD is conformal whatever the aspect ratio, MOCVD is not suitable for vias with an aspect ratio higher than 5:1, whereas FAST can achieve a conformality higher than 60% in aspect ratios of 35:1.