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DS: Fachverband Dünne Schichten
DS 11: Symposium: New Materials for Nanoelectronics
DS 11.9: Vortrag
Dienstag, 27. März 2007, 13:00–13:15, H32
Determination of the coefficient of thermal expansion (CTE) of porous dielectric films using x-ray reflectometry — •Sebastian Taube, Holm Geisler, Ulrich Mayer, Inka Zienert, Michael Hecker, and Ehrenfried Zschech — AMD Saxony LLC & Co. KG, Wilschdorfer Landstr. 101, D-01109 Dresden, Germany
In advanced integrated circuits thin interlayer dielectric (ILD) films with reduced relative permittivity (k) will be used for reducing crosstalk and interconnect signal delay. It is the final goal to achieve as small as possible k-values which are close to the physical limitation ( kvacuum=1). For reaching lowest possible k values, new materials or nano porous layers are potential candidates. However, these layers have many different properties in comparison with the traditionally used silica glass, e.g., considerably reduced mechanical stiffness. The CTE value is one important property of such an ILD layer. The advanced integrated circuits undergo during the fabrication and later in the practice permanent changing temperature cycles. Thin film stacks with relatively large differences in the CTE of the individual thin films are a reliability concern for microelectronic products. The thickness of a thin film as well as the variation of the thickness due to increased temperature can be measured very precisely with XRR. It will be shown here that the CTE of (ultra) low-k layers can be determined for relevant process and application temperatures with the XRR method. The measured CTE values are typically higher than for metals, e.g., copper.