Bottom-Up Engineering of Subnanometer Copper Diffusion Barriers Using NH2-Derived Self-Assembled Monolayers

Autor: Gustaaf Borghs, Guido Maes, Caroline Whelan, Olivier Richard, Arantxa Maestre Caro, Silvia Armini, Youssef Travaly
Rok vydání: 2010
Předmět:
Zdroj: Advanced Functional Materials. 20:1125-1131
ISSN: 1616-3028
1616-301X
Popis: A 3-aminopropyltrimethoxysilane-derived self-assembled monolayer (NH 2 SAM) is investigated as a barrier against copper diffusion for application in back-end-of-line (BEOL) technology. The essential characteristics studied include thermal stability to BEOL processing, inhibition of copper diffusion, and adhesion to both the underlying SiO 2 dielectric substrate and the Cu over-layer. Time-of flight secondary ion mass spectrometry and X-ray spectroscopy (XPS) analysis reveal that the copper over-layer closes at 1-2-nm thickness, comparable with the 1.3-nm closure of state-of-the-art Ta/TaN Cu diffusion barriers. That the NH 2 SAM remains intact upon Cu deposition and subsequent annealing is unambiguously revealed by energy-filtered transmission electron microscopy supported by XPS. The SAM forms a well-defined carbon-rich interface with the Cu over-layer and electron energy loss spectroscopy shows no evidence of Cu penetration into the SAM. Interestingly, the adhesion of the Cu/NH 2 SAM/SiO 2 system increases with annealing temperature up to 7.2 J m -2 at 400°C, comparable to Ta/TaN (7.5 J m -2 at room temperature). The corresponding fracture analysis shows that when failure does occur it is located at the Cu/SAM interface. Overall, these results demonstrate that NH 2 SAM is a suitable candidate for subnanometer-scale diffusion barrier application in a selective coating for copper advanced interconnects.
Databáze: OpenAIRE
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