Property of Universal Chiplet Interconnect Express (UCIe) 2022
Universal Chiplet Interconnect Express (UCIe)®: Building an open chiplet ecosystem
Dr. Debendra Das Sharma
Intel Senior Fellow and Chief Architect, I/O Technologies and Standards
Promoter Member of UCIe
Universal Chiplet Interconnect Express (UCIe)® is an open industry standard interconnect
offering high-bandwidth, low-latency, power-efficient, and cost-effective on-package connectivity
between chiplets. It addresses the projected growing demands of compute, memory, storage, and
connectivity across the entire compute continuum spanning cloud, edge, enterprise, 5G, automotive,
high-performance computing, and hand-held segments. UCIe provides the ability to package dies from
different sources, including different fabs, different designs, and different packaging technologies.
Motivation for on-package integration of Chiplets
In his seminal paper “Cramming more components onto integrated circuits” (published in
Electronics, Volume 38, Number 8, on April 19, 1965), Gordon Moore posited that the number of
transistors in an integrated circuit will double every two years. Popularly known as “Moore’s law”, it has
held up for more than 50 years thus far. In the same paper, Gordon Moore also predicted the “Day of
Reckoning”: “It may prove to be more economical to build large systems out of smaller functions, which
are separately packaged and interconnected.” Today we see on-package integration of multiple dies in
mainstream commercial offerings such as client CPUs, server CPUs, GP-GPUs, etc.
There are many drivers for on-package chiplets. As the die size increases to meet the growing
performance demands, designs are running up against the die reticle limit. Examples include multi-core
CPUs with core count in the hundreds or very large fanout switches. Even when a die can fit within the
reticle limit, multiple smaller dies connected in a package may be preferable for yield optimization as
well as die reuse across multiple market segments. On-package connectivity of identical dies enables
these scale-up applications.
Another motivation for on-package integration is to lower the overall portfolio cost both from a
product as well as project point of view and derive a time to market advantage. For example, the
compute cores shown in Figure 1 can be implemented in an advanced process node to deliver
leadership power-efficient performance at higher cost whereas the memory and I/O controller
functionality may be reused from a design already deployed in an established (n-1 or n-2) process node.
Such partitioning also results in smaller dies which results in better yield. IP porting costs across process
nodes are high and increasing very rapidly for the advanced process nodes, as shown in Figure 2. Since
we don’t have to port all the IPs of dies whose functionality does not change, we save on costs in
addition to getting the time to market advantage. Chiplet integration on package also enables a
customer to make different trade-offs for different market segments by choosing different numbers and