Ultra-HDI with low cost photo-imageable polymers

As IC devices continue to drive to finer and finer feature sizes, so must the packaging to support them. High-density-interconnects (HDI) fabricated on low cost organic laminates is widely regarded as a critical enabler for device and wafer level packaging. System-on-a-package (SOP) is rapidly being accepted as the future means by which ICs and other components will be packaged. However, if SOP is to be successful, low cost materials and processes must be optimized to reliably yield fine line structures. The PRC has been working to meet a number of challenges that confront the successful implementation of SOP. One of those challenges manifests itself in the area of fine line lithography. Here, low cost photoresists and photo-imageable polymer materials are being evaluated. In addition, processes to support these materials must be optimized for developing ultra fine line HDI substrates. Line widths and spaces of 10-15 μm and microvia diameters of 25-50 μm have been achieved on large area organic laminates. This paper discusses a number of critical process and material issues that may affect the integrity of fine line and microvia formation