Atomic layer deposition of tantalum nitride for ultrathin liner applications in advanced copper metallization schemes

Abstract

A metal–organic thermal atomic layer deposition (ALD) approach was developed for the growth of ultrathin tantalum nitride (TaNx) films by alternate pulses of tert-butylimido trisdiethylamido tantalum (TBTDET) and ammonia (NH3). An optimized ALD process window was established by investigating saturation of film-growth rate versus TBTDET and NH3 exposures, as controlled by the length of reactant pulses and the duration of the inert gas purge cycles separating the reactant pulses. The resulting low-temperature (250 °C) ALD process yielded uniform, continuous, and conformal TaNx films with a Ta:N ratio of 1:1. Carbon and oxygen impurity levels were in the 5–8 at.% range. Associated film conformality in 100-nm trench structures with 11:1 aspect ratio was nearly 100%.

Synthesis and in situ characterization of low-resistivity TaNx films by remote plasma atomic layer deposition

“…TaN is considered as a candidate to replace the poly-Si gate in metal-oxidesemiconductor field effect transistors, 1 as metal electrode in high-density three dimensional ͑3D͒ capacitors, 2 and as Cu diffusion barrier [3][4][5] and possible liner material for interconnect technology. 6,7 In addition to a high level of growth control, several applications require conformal deposition in high-aspect ratio structures, which is a requirement beyond reach of current physical vapor deposition ͑PVD͒ techniques. Due to its layer-by-layer growth, atomic layer deposition ͑ALD͒ is believed to be the method of choice for deposition in demanding 3D features.…”

Computational study on transamination of alkylamides with NH3 during metalorganic chemical vapor deposition of tantalum nitride

“…While TaN films grown by CVD at $600 1C using TBTDET as a single-source precursor demonstrated reasonable barrier properties [2,3], ammonia (NH 3 ) has also been introduced as a secondary precursor to reduce carbon contamination (increase nitrogen content) in the deposited films and increase the film density [4]. The temperature for growth in the presence of NH 3 was lowered sufficiently (down to 300 1C) for the process to be also applicable to atomic layer deposition (ALD) [1,4,[6][7][8]. The transamination between alkylamide ligands in the MO source and NH 3 has been invoked as the key process for film deposition [9][10][11][12].…”

Bis(tert‐butylimido)‐bis(dialkylamido) Complexes of Molybdenum as Atomic Layer Deposition (ALD) Precursors for Molybdenum Nitride: the Effect of the Alkyl Group

“…[18][19][20][21][22] With the halide-ammonia ALD system, relatively high deposition temperatures, usually 400-600 8C, have to be used and aggressive hydrogen halides are released as a side product. Recently, novel metal-organic precursors containing amido and imido ligands have been introduced for tantalum, [23] tungsten, [24] and molybdenum. [25] With these new precursors, lower deposition temperatures can be applied and the emission of corrosive side products is avoided.…”

“…[23] Bis(tert-butylimido)-bis(dimethylamido)tungsten [( has also been reported to be applicable in molybdenum nitride CVD. [26] Apart from the above-mentioned benefits, amido-imido precursors are more thermally unstable than halide precursors.…”