Multi-method characterization approach to facilitate a strategy to design mechanical and electrical properties of sintered copper

Abstract

Advanced die application materials, utilizing pressure-less sintered copper, show great prospects regarding cost effectiveness, power density, withstanding high switching speeds and temperature loading for novel eco-friendly and high efficiency semiconductors. In general, to preserve high reliability in combination with electrical functionality the design of elastic as well as electrical material parameters is of great importance. Here, we present a multi-method characterization approach to understand the impact of the morphology on the elastic as well as electrical behavior, which facilitates a strategy to design the relevant material parameters by tuning the morphology. Nano-SEM/FIB tomography and SEM/EBSD are applied to probe the morphology of three representative copper films. Nanoindentation and 4-point probe are used to extract the elastic modulus and specific electrical resistivity, respectively. The evaluated material parameters are compared with modeling results using the analyzed image data as an input. For the crucial image analysis, we develop a validated objective image analysis workflow. We obtain a quantified insight about the effect of the heterogeneous morphologies on the elastic modulus and specific electrical resistivity, thereby delivering important information about the necessary homogeneous copper morphology- and nano-scale pore-design. The strategy shall provide design guidelines to ensure reliable and high-performance die attachments.

Keywords

• Sintered materials
• Computational image analysis
• Tomography
• Elastic modulus
• Specific electrical resistivity
• RVE finite element method