No abstract

Cu-Al intermetallic compound (IMC) in Cu wire-Al bond pad interconnect interface is drawing attention of researches. However, due to thin IMC thickness, the characterizations of the IMC are limited to expensive and time consuming techniques. An evaluation is performed to use common X-Ray Diffraction (XRD) technique to identify the IMC in the Cu wired micro-chip samples in powder form. Existence of mixture of CuAl and CuAl2 was first confirmed by transmission electron microscope (TEM) and energy dispersive X-ray (EDX). In XRD analysis, peak correspond to CuAl phase is identified from measurement with slower scan configuration. The difficulty for IMC peak detection in diffractogram is due to low composition ratio of IMC relative to other materials available in the sample. KOH treatment for enhancing IMC peaks intensity does not work as expected as it etches the IMC as well.

The nanostructural characteristics of direct-current magnetron sputter-deposited Ni4Al alloy films were studied during in situ isothermal annealing in a transmission electron microscope (TEM). An expansion of the lattice by nearly 5% was observed for the synthesized films in their low-thickness and as-deposited state. The lattice size approaches the bulk value when the film thickness increases or after vacuum annealing heat-treatment. The Ni4Al films have a nanocrystalline structure in which the ordered L12 phase appears upon annealing at above 500°C. A grain coalescence trend was found for the Ni4Al films during the in situ annealing above 500°C. This can be the main reason for the abnormal grain growth of these films at these high temperatures.

"Goes Green & Copper", is the strategy to introduce 1) environmentally friendly materials to meet RoHS (Restriction of the use of Hazardous Substances) & WEEE (Waste Electrical & Electronic Equipment) requirements and 2) Cu wires for superior electrical, mechanical & intermetallics properties compared to Au wires. A complete package level qualification was planned to assess the reliability performaces in discrete packages. This paper will discuss in details on investigation of lateral die crack failure during reliability. Process & materials investigation revealed that interaction of leadframe paddle construction, die attach method, die construction & mold compound factors play important role in aggravating lateral die crack. FEA (finite element analysis) was performed to understand the thermo-mechanical stress distribution within the die & package. Re-qualification was performed & reliability results showed that lateral die crack failure could be eliminated with proper combination of BOM selection.