A new atomic layer deposition method and electrical performance of WN diffusion barrier for Cu nano via contact structures

Title
A new atomic layer deposition method and electrical performance of WN diffusion barrier for Cu nano via contact structures
Authors
김영환황영현조원주김용태
Keywords
WN; diffusion barrier; Cu nano via/contact; Atomic layer deposition
Issue Date
2012-05
Publisher
European Materials Research Society (E-MRS), 2012
Abstract
3 Dimensional Cu through via structure offers a new era for integration of logic and memory devices. However, for the practical application of Cu 3D via structure, a diffusion barrier material is essential for preventing Cu interdiffusion. Particularly, atomic layer deposition (ALD) is neccessary for the conformal deposition of very thin diffusion layer in the nano scaled via structure. In this work, we have compared electrical performance, thermal stabilities and reliabilities of ALD-WN diffusion barrier with TiN diffusion barrier that is popularly used for conventional contact structures. WN-ALD is carried with WF6, B2H5, and NH3. Although WF6 has a problem such as encroachment on the Si surface, predepostion of B2H5 enables to prevent the encroachment. The proposed ALD method shows that lower resistivity can be achieved without encroachment. Electrical performance, thermal stability and reliability of Cu contacts are compared with TiN and WN diffusion barriers before and after the annealing at 700℃ for 30min. The via contact size is 100x100nm and the aspect ratio is 20. All of the Cu/WN/Si contacts maintain low contact resistance and show excellent reliability comparing with the Cu/TiN/Si contacts because the WN diffusion barrier prevents successfully the Cu inter-diffusion and the Cu contact keeps the initial contact resistance. Thermal stability also suggests that the reliability of Cu/WN/Si contact is excellent even after the annealing at 700℃ for 30 min.
URI
http://pubs.kist.re.kr/handle/201004/42760
Appears in Collections:
KIST Publication > Conference Paper
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