Highly Thermal-Stable Amorphous TaSi[sub 2]C[sub x] Films as Diffusion Barrier

Abstract

Structural changes at high temperature of amorphous TaSi 2 C x films deposited on Si͑100͒ were evaluated. Increased carbon content remarkably raises crystallization temperature; thus, TaSi 2 C x films ͑x Ͼ 16 atom %͒ sustain amorphous phase at 800°C for at least 30 min. A preliminary evaluation of such films as a diffusion barrier of Cu metallization in a sandwich scheme Si͑100͒/TaSi 2 C x ͑20 nm͒/Cu showed the stability of 750°C ͑x = 19 atom %͒ or 800°C ͑x = 22 atom %͒ for at least 5 min without a sharp increase in sheet resistance nor the formation of Cu 3 Si. Because Ta, Si, and C are compatible with integrated-circuit processing, these films are readily applicable as diffusion barriers in Cu metallization.

Structural Evolution and Electronic Properties of TaSin–/0 (n = 2–15) Clusters: Size-Selected Anion Photoelectron Spectroscopy and Theoretical Calculations

“…Transition-metal (TM) atom doped silicon clusters can form stable fullerene-like structures − and also can exhibit novel electronic properties. − They may be used as potential building blocks for producing novel silicon-based nanomaterials. − Ta–Si clusters have received great attention because tantalum is widely used in alloys and nanomaterials. It has been found that Ta–Si film can be used for manufacturing capacitors and resistors with excellent thermal stability. − TaSi x nanostructure film can be used as a barrier material for Cu metallization, and silicide TaSi 2 film can be used as Schottky barriers and ohmic contacts with high-temperature mechanical strength and oxidation resistance . Han et al conducted theoretical calculations on neutral TaSi n ( n = 1–13) using relativistic density function theory (RDFT) methods with a frozen-core triple-basis set plus polarization function.…”

“…21 Han et al 22 conducted theoretical calculations on neutral TaSi n (n = 1−13) using relativistic density function theory (RDFT) methods with a frozen-core triple-basis set plus polarization function. Theoretical calculations showed that the most stable isomer of TaSi 16 + is a fullerene-like structure with a slightly distorted C 4v symmetry. 23 TaSi n (n = 1−3, 12) clusters supported on the graphene surfaces were also investigated using the PBE functional with the projected augmented wave (PAW) pseudopotentials.…”

Failure Mechanism of 5 nm Thick Ta–Si–C Barrier Layers Against Cu Penetration at 750–800°C

“…In our previous work, carbon was chosen for better controlling film composition and improving thermal stability of the ternary Ta-Si-C films. 12 It led to a 5 nm thick Ta 34 Si 47 C 18 film which has a failure temperature of at least 750°C while maintaining a reasonable resistivity of 340 ⍀ cm. 13 Moreover, the Ta-Si-C layer is highly compatible with integrated circuit processing, because these elements have been routinely adopted in today's ultralarge-scale integration technologies.…”

Comparative Study of Cu Diffusion in Ru and Ru-C Films for Cu Metallization

“…Addition of other elements into the barrier layer often randomizes the lattice of the barrier film and consequently enhances its effectiveness as a diffusion barrier for the Cu metallization, such as the TaSiC and TaSiN. 33,34 In our previous study of 15 nm thick Ru and Ru-Ta barrier films, the failure temperature of amorphous Ru-Ta films is 700°C ͑annealing for 30 min͒, which is 200°C higher than that of a crystalline Ru film 35 and is inferior to the 5 nm thick Ru-C film ͑failed after annealing at 800°C for 30 min͒. Although the addition of Ta in Ru film makes the barrier structure amorphous and consequently diminishes the grain boundaries for Cu diffusion, the greater atomic radius of Ta ͑0.143 nm͒ 7 than that of Ru ͑0.134 nm͒ may lead to the production of vacancies between Ru and Ta atoms.…”