SEMICON Taiwan 2025 Silicon Photonics Summit | AMD | UCIe, Heterogeneous Integration and the Road to CPO

Introduction

AI compute demand has grown rapidly over the past few years, driving large-scale adoption of GPUs and accelerators. But as compute scale keeps expanding, interconnect technology, package design and energy consumption challenges have become the industry's key pain points.

At the SEMICON 2025 Silicon Photonics Summit, AMD shared its views on heterogeneous integration, the UCIe standard, co-packaged optics (CPO) and package yield challenges, stressing that for silicon photonics to truly take hold, everything from design tools and processes to supply chain collaboration must improve.

Content

1. Explosive Demand for AI Models and Chips

• AI model generations are turning over faster, with demand growing faster than the doubling curve of the past.

• AMD's MI300 series uses 3D hybrid bonding and CoWoS packaging, reaching 80 billion transistors, showing the strong potential of heterogeneous integration.

2. UCIe and Package Integration

• UCIe (Universal Chiplet Interconnect Express) is seen as the future standard interface for heterogeneous integration and optical I/O.

• AMD stressed that combining optical I/O with UCIe is still limited by:

  • Fiber count limits: packages still can't support enough fibers today.

  • Yield and cost challenges: reaching scale requires major improvements in design flow and process control.

• The industry must keep pushing PDK (Process Design Kit) maturity to improve accuracy and reliability from design to manufacturing.

3. The Challenges of Co-Packaged Optics (CPO)

• AMD noted that while CPO is the future trend, three major problems remain:

  1. Package yield: in giant packages of 120×120 mm and above, integration yield of optical components and electronic ICs is still a pain point.

  2. Thermal management: in high-density packages, cooling optical/electrical components and the GPU at the same time remains unsolved.

  3. Laser reliability: the laser is the "single point of failure" of optical interconnect, and its lifetime and stability are more challenging than other optical components.

4. Supply Chain and Industry Ecosystem

• The optical component supply chain is still highly fragmented:

  • A few suppliers can deliver high-quality lasers, but not in enough volume to meet a future where every GPU needs optical I/O.

  • Optical module assembly and fiber verification are still largely manual; more automation is needed to support volume production.

• AMD believes industry collaboration and supply chain integration are the keys to successful deployment of CPO and optical I/O.

5. Looking Ahead

AMD's observations on the future of silicon photonics:

1. Optics is the only solution: as bandwidth demand keeps doubling, electrical links can no longer keep up.

2. PDKs must mature: photonic PDKs aren't stable enough today and need further improvement to support volume production.

3. Packaging must be considered at the design stage: heterogeneous integration flows need to account for optics early in design to avoid back-end yield and cost problems.

4. Reliability is key: especially laser lifetime and package testing, which directly affect customers' willingness to adopt.

Conclusion

AMD's talk at SEMICON 2025 showed a clear-eyed understanding of the future of heterogeneous integration and silicon photonics:

• Optical interconnect is the only technology that can solve the bandwidth and energy-efficiency challenges of the AI era.

• UCIe standardization will be key to driving heterogeneous integration and optical I/O.

• CPO deployment still faces challenges in package yield, thermal management and laser reliability.

• The industry needs more mature PDKs, supply chain integration and cross-industry collaboration to achieve true deployment at scale.

AMD's message was direct: optics is the future, but making it a reality will take a joint effort across the entire industry chain.