Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Abstract

RC-time delay in Cu interconnects is becoming a significant factor requiring further performance improvements in future nanoelectronic devices. Choice of alternate interconnect materials, as for example, refractory metals, and subsequent integration with underlying barrier and liner layers are extremely challenging for the sub-10 nm nodes. The development of conformal deposition processes for alternate interconnects, liner, and barrier materials are crucial in order for implementation of a possible replacement for Cu interconnects for narrow line widths. In this study we report on ultra-thin (~ 3nm) chemical 2 vapor deposition (CVD) grown ruthenium films on 0.5 and 1 nm thick metal nitride (TiN, TaN) barrier layers deposited via atomic layer deposition (ALD). Using scanning electron microscopy, we determined the effect of the underlying barrier layer on the coverage of the ruthenium overlayer. We utilized synchrotron x-ray diffraction with in-situ rapid thermal annealing to investigate the thermal stability of the barrier layers and determine the effective activation energies of barrier failure leading to ruthenium monosilicide formation.For Ru films deposited directly on Si and on 0.5 nm MN (M=Ti, Ta) covered Si substrates, silicide formation proceeds via a two-step crystallization process involving lateral nucleation above ~ 440 °C followed by thickening of the ruthenium monosilicide layer above ~520 °C. This silicidation temperature of ~ 440 °C could be potentially problematic in back-end-of-the-line (BEOL) processing since it is close to the typical thermal budget used. However ~1 nm thick ALD MN (M=Ti, Ta) was found to be adequate to block silicide formation up to ~ 580 °C and ~ 620 °C for TiN and TaN, respectively, and also aided in superior coverage of the CVD ruthenium overlayer (>90%). The results reported here might be useful to ascertain annealing temperature and time for BEOL process and integration optimization without reaching a state where ruthenium silicides start forming.

The lower energy diffraction and scattering side-bounce beamline for materials science at the Canadian Light Source

“…Low-level motor control is accomplished with EPICS. The endstation was operational and producing scientific results (Dey et al, 2017;Motamedi et al, 2018) at the IDEAS beamline at the CLS before moving to the LE beamline in August 2020. It now occupies the outboard side of the hutch at a 2 = 29 , resulting in fixed energies of 7.9 keV using Si(111) or 15.1 keV using Si(311).…”

Atomic Layer Modulation of Multicomponent Thin Films through Combination of Experimental and Theoretical Approaches

“…In this study, RuAlO x ALM using Ru and Al 2 O 3 ALD was employed as a model system. Owing to its electrical and chemical stability, Ru ALD has been applied to liner materials in 3-dimensional Si nanodevice interconnects. , The modulation of Ru with Al 2 O 3 , a well-known amorphous atomic insulator, could improve the Ru ALD diffusion barrier. , In our previous work, metallic Ru was obtained using an H 2 O counter reactant and an Ru precursor, dicarbonyl- bis (5-methyl-2,4-hexanediketonato)­Ru­(II) (Carish) . In this work, trimethylaluminum (TMA) and Carish Ru precursors were employed.…”

Some Insights into Atomic Layer Deposition of MoNx Using Mo(CO)6 and NH3 and Its Diffusion Barrier Application

“…This could lead to its possible implementation in the semiconductor industry because the maximum processing temperature on Cu metallization in semiconductor devices is generally lower than ∼450 °C owing to the integration of low- k materials. However, the failure of the barrier layer strongly and directly depends on the thickness of the layer . With a reduction in the thickness of the barrier layer, the failure temperature is targeted as a higher value.…”

“…However, the failure of the barrier layer strongly and directly depends on the thickness of the layer. 10 With a reduction in the thickness of the barrier layer, the failure temperature is targeted as a higher value. Additionally, these materials should also have high melting points, low reactivity with Si, and good adhesion characteristics.…”