Numerical analysis of geometry effects for target re-deposition during low pressure hollow cathode magnetron sputtering

During low pressure ionized metal physical vapor deposition (PVD) of Cu seed layer for microprocessor interconnects, the re-deposited Cu film on the hollow cathode magnetron (HCM) target may fall off and damage the Cu film on the wafer. An analytical view factor model based on the analogy between me...

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Bibliographic Details
Published in:Vacuum 2011-01, Vol.85 (6), p.657-661
Main Authors: Lu, Junqing, Tao, Guoqing, Lee, Chan Gyu, Yoon, Jae Hong, Cho, Tong Yul
Format: Article
Language:English
Subjects:
Copper
Disks
Hollow cathode magnetron
Hollow cathodes
Ionized PVD
Low pressure
Magnetron sputtering
Mathematical models
Numerical analysis
Physical vapor deposition
Sputtering
Target erosion
View factor
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Summary:During low pressure ionized metal physical vapor deposition (PVD) of Cu seed layer for microprocessor interconnects, the re-deposited Cu film on the hollow cathode magnetron (HCM) target may fall off and damage the Cu film on the wafer. An analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was used to obtain re-deposition profiles for HCM targets in low pressure (below 0.1 Pa) Cu ionized PVD. The model predictions indicate that there is an inherent non-uniformity in the re-deposition profile even for uniform sputtering over the entire HCM target. The predicted re-deposition profile agrees with experimental observations. Subsequent target redesign studies found that the non-uniformity in the re-deposition profile could be mitigated by using a conical sidewall between the top disk and the cylindrical sidewall or reducing the length of the cylindrical sidewall.
ISSN:0042-207X
1879-2715
DOI:10.1016/j.vacuum.2010.07.016