edfas.org 15 ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 26 NO. 3 the fine-pitched features of their designs are under x-ray inspection. It utilizes a combination of x-ray image data collection, analysis, and simulations to evaluate different design elements. This enables designers to base their decisions on solid data, improving the chances of successful inspection results. For instance, the metric can help identify areas prone to noise scattering or places with spacings too small to resolve, allowing for adjustments before starting the manufacturing process. Such early interventions can optimize manufacturability, decrease the likelihood of expensive redesigns, and accelerate the product’s time-tomarket. Incorporating this metric at the pre-silicon stage represents a proactive and structured method to tackle the challenges associated with x-ray inspection, ultimately improving reliability and production yield. BACKGROUND AND MOTIVATION The evolution of IC packaging (as shown in Fig. 2) has been marked by significant transitions, reflecting the advancements in technology and the growing demands for performance and miniaturization. Initially, the industry relied on simpler formats like the single inline package and dual inline package, which set the foundation for IC packaging. However, as the need for higher pin counts and enhanced performance grew, more advanced solutions were developed, such as the pin grid array (PGA) and quad flat package (QFP). These innovations allowed for greater complexity and functionality in IC design. A pivotal shift occurred with the adoption of surface mount technology (SMT), epitomized by packages like the ball grid array (BGA) and flip-chip ball grid array (FCBGA). This transition from pins to bumps represented a significant step towards miniaturization, enabling the production of smaller, more functional ICs. This change was instrumental in accommodating the increasing demands of compact and efficient electronic devices. The latest developments in the field have been even more revolutionary, focusing on 2.5D and 3D packaging technologies. These approaches involve stacking multiple IC dies or placing them side by side. Such configurations offer substantial performance gains and a reduction in form factor, crucial for the current era of high-performance computing. These innovations are at the heart of cutting-edge technologies, driving progress in sectors like data centers and high-performance computing, with applications in advanced products like GPUs, APUs, FPGAs, and more. Each of these steps reflects the ongoing journey of IC packaging, showcasing an industry continuously pushing the boundaries of what’s possible in electronic component design and functionality. When we discuss the incredible advancements in microelectronics today, it’s essential to focus on the interconnect level, particularly at die-to-die and dieto-substrate interfaces. This focus is crucial for implementing various packaging technologies while ensuring reliability and longevity. The ongoing adaptation of the redistribution layer (RDL), coupled with the development of new interconnect architectures like through-silicon vias (TSVs) and microbumps, is driven by the trend of shrinking interconnect dimensions, lower feature pitch, and thinner material layers.[9] Concurrently, back-endof-line (BEOL) processes have become more intricate, bridging the gap between rapidly scaling transistors and the slower pace of interconnect miniaturization. Modern BEOL stacks often comprise over ten metal layers, featuring complex chip-packaging interaction (CPI) structures, while TSV and bump features shrink from hundreds to tens and even single-digit micrometers in size. As a result, analyzing these intricate products and pinpointing the fundamental causes of failure, such as issues in packaging design and production techniques, has grown increasingly Fig. 2 Evolution vector of packaging in the semiconductor industry.
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