Intel Foundry Advanced Packaging Evolution and EMIB Development for Artificial Intelligence Workloads and Future Semiconductor Architecture Solutions
The semiconductor industry is at a turning point where shrinking transistors is no longer sufficient to support the massive computational power needed for modern artificial intelligence. In a comprehensive interview conducted by Intel Foundry, Intel Fellow Ravi Mahajan described how packaging has moved from being a mere supporting component to the foundation of all modern computer architecture. With over three decades of experience at Intel, Mahajan has been leading this transformation and has served as a principal director for the pathfinder teams that set the directions for modern chip connectivity.
Traditionally, all improvements came from utilizing Moore's Law, where shrinking transistors and increasing their density were the main routes to improving performance within a single silicon chip. However, the massive data movement and massive compute requirements of today's AI workloads require not just faster data speeds, but also massive memory bandwidth and extreme power efficiency. Mahajan explained that modern packaging technology has emerged as the main method to unlock these needs and integrate discrete chips onto a single system.
When Mahajan joined Intel, nearly thirty years ago, packaging was a "behind the scenes support function whose only main objective was to support the delicate silicon and to manage its minor thermal output". The main concern of early day thermal engineers was "a couple of watts", now, they have to address "kilowatt level" workloads.
The need to address power delivery and connectivity requirements for large clusters of discrete high performance compute chips, also known as silicon interconnectivity needs, led to the conception of Embedded Multi die Interconnect Bridge (EMIB), a concept that is commercially known as EMIB. Mahajans' team initially started researching the physical limits of interconnectivity in the early 2000s. Traditional packaging substrate had been the primary connector in terms of routing wires to transfer signals between separate chips, and standard substrates could no longer route signals to the extremely fine pitches necessary. Consequently, engineers began looking into "a silicon based interposer which will get embedded into the standard silicon substrate packaging".
The concept behind EMIB is to take a small silicon piece, embed it into the package, and to use this piece of silicon as an interposer that connects the chips at very fine pitches. In principle it seems easy, but required numerous complex engineering challenges such as materials used, managing stress and manufacturability. By 2013 Intel believed the technology to be mature enough to incorporate into a production process and in 2014 introduced it formally. It has been widely adopted since to deliver performance that previously required monolithic designs.
Intel Foundry's customers can leverage advanced packaging technology to greatly enhance the design possibilities, Instead of having one massive monolithic die which is hard to fabricate and to yield designers can bring together a small number of optimal discrete components into one single package, mixing process technologies, enabling designs across process technologies and vendors, and getting past physical limitations in lithography reticle size. This is critical for the AI system that is limited fundamentally by the speed at which data can be moved between processors and memory, with advanced packaging providing a dense and energy efficient solution, reducing the physical distance data must be transported. Mahajan emphasizes the impossibility to meet the demands with just the current scaling methodology, especially for AI hardware.
The complexity of modern advanced packaging is giving rise to challenges for designers working on interconnect delivery, power distribution, thermal management and yields. Clean power delivery to modern silicon clusters is just as important as fast data movement. Mahajan points out that all of these need to be done through materials and process engineering experts that will rely on sophisticated thermal modeling, and materials science experts, among others, to enable these challenges to be overcome.
Mahajan is also expecting materials and design paradigms of the packaging world to change significantly over the next decade. Co packaged optics is one of these. It could potentially help move the data path from electrical signals to light based signals that provide much greater bandwidth and glass is the primary material for substrates going forward, with improvements to both scalability and physical characteristics of advanced multi chip packages. Industry cooperation is necessary to create robust manufacturing pipelines with common standards and coordinated efforts in equipment, design methodology and tooling. Mahajan believes Intels’ strong history in both research and high volume manufacturing position it well to lead this upcoming technological wave.
