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2016
Conference Paper
Titel
Novel approaches to determine thermomechanical materials data in advanced interconnect stacks
Abstract
Novel approaches for the determination of effective materials data such as Young's modulus and Coefficient of Thermal Expansion (CTE) are described for particularly defined building blocks of interconnect stacks of microelectronic products. These building blocks are simplified regions of interest needed for compact model-based FEA simulations. For these regions of interest, ¿¿¿smeared composite data¿¿¿, e. g. for the Backend-of-Line (BEoL) stack, are determined. Effective CTE values for Cu/ULK on-chip interconnect stacks were determined for particularly prepared samples, measured at several temperatures in the Scanning Electron Microscope (SEM). The experimental results show a significant effect of the Cu/ULK volumetric ratio on the CTE value, and an influence of the Cu line direction in the BEoL on the effective CTE value. The Nanoindentation (NI) technique was used to measure the in-plane effective Young's modulus values. Along with the CTE values, the effective modulus values are useful input for the analysis of the local and global stress in chips, particularly when they are stacked 3-dimensional.
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