Surface properties restoration and passivation of high porosity ultra low-k dielectric (k ∼ 2.3) after direct-CMP |
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Authors: | F. Sinapi,N. Heylen,G. Vereecke,E. Kesters,J.L. Hernandè z,P. Fischer |
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Affiliation: | a IMEC vzw Kapeldreef 75, B-3001 Leuven, Belgium b Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497, US |
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Abstract: | Surface hydrophilisation and effective k-value degradation have been reported in literature after direct-CMP of high porosity SiOC films (without a protective capping layer). In the sequel, attempts to restore ultra low-k (ULK) material initial properties after a standard CMP and post-CMP cleaning process are reported. Annealing treatment has shown to be valuable to remove residual organics and water absorbed at the ultra low-k material surface after direct-CMP. However, as the hydrophilicity of the polished surface remains unchanged, it does not prevent moisture uptake, leading to an increase in k-value with time. Therefore, in order to restore hydrophobic properties and to stabilize the surface in time, three silylating agents - containing chlorosilane reactive groups (-SiMenCl3−n) as well as hydrophobic methyl functions (-CH3) in their structure - have been employed in liquid, gas or dense CO2 phases on the CMP-induced damaged ULK layers. While each of these organic treatments is efficient to restore hydrophobicity on post-CMP ULK surfaces, only one of them proved to be able to keep the k-value low (comparable to the ULK pristine k-value) and stable in time, without inducing significant change in porosity of the ULK material. |
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Keywords: | Post-CMP ULK Silylation Hydrophobicity k-value |
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