An Introduction to the Universal Chiplet Interconnect Express® (UCIe®)

The Universal Chiplet Interconnect Express (UCIe) is an open industry standard designed to enable seamless interconnection of chiplets through planar and vertical connectivity on-package. With UCIe, a system designer can construct a system-in-package (SiP) by integrating chiplets sourced from multiple vendors, manufactured on heterogeneous process nodes across different foundries, packaged through any OSAT (Outsourced Semiconductor Assembly and Test) company, all while maintaining guaranteed interoperability. The standard is being actively driven by a broad coalition of stakeholders, including major silicon providers, foundries, OSATs, IP vendors, automotive vendors, and cloud service providers, under the umbrella of the UCIe Consortium. On-package integration of chiplets is essential for systems as it offers significant power and performance advantages over monolithic chips and enables bespoke solutions, while the openness of the ecosystem fosters innovation across ecosystems. This survey introduces UCIe through the lens of its evolutions spanning three generations and highlights its importance in enabling a wide range of cost-effective systems using diverse packaging strategies. We also examine existing UCIe implementations. We explore the key challenges the chiplet ecosystem must address as its adoption proliferates and system architecture needs to evolve across the compute landscape to address the ever increasing demand of compute.